US20020017612A1 - Organic diodes with switchable photosensitivity useful in photodetectors - Google Patents
Organic diodes with switchable photosensitivity useful in photodetectors Download PDFInfo
- Publication number
- US20020017612A1 US20020017612A1 US09/930,771 US93077101A US2002017612A1 US 20020017612 A1 US20020017612 A1 US 20020017612A1 US 93077101 A US93077101 A US 93077101A US 2002017612 A1 US2002017612 A1 US 2002017612A1
- Authority
- US
- United States
- Prior art keywords
- photodiode
- organic
- electrode
- derivatives
- voltage
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 206010034972 Photosensitivity reaction Diseases 0.000 title claims abstract description 75
- 230000036211 photosensitivity Effects 0.000 title claims abstract description 75
- 238000003491 array Methods 0.000 claims abstract description 51
- 239000010410 layer Substances 0.000 claims description 112
- 239000000758 substrate Substances 0.000 claims description 63
- 230000004044 response Effects 0.000 claims description 60
- 230000003287 optical effect Effects 0.000 claims description 54
- 229920000642 polymer Polymers 0.000 claims description 53
- 239000000463 material Substances 0.000 claims description 48
- 239000011159 matrix material Substances 0.000 claims description 47
- 239000000203 mixture Substances 0.000 claims description 39
- 230000003595 spectral effect Effects 0.000 claims description 38
- -1 poly(phenylenevinylene) Polymers 0.000 claims description 33
- 229920000553 poly(phenylenevinylene) Polymers 0.000 claims description 29
- 238000000034 method Methods 0.000 claims description 22
- 239000004065 semiconductor Substances 0.000 claims description 20
- 239000012044 organic layer Substances 0.000 claims description 19
- 229920000547 conjugated polymer Polymers 0.000 claims description 18
- MWPLVEDNUUSJAV-UHFFFAOYSA-N anthracene Chemical compound C1=CC=CC2=CC3=CC=CC=C3C=C21 MWPLVEDNUUSJAV-UHFFFAOYSA-N 0.000 claims description 16
- 229920001940 conductive polymer Polymers 0.000 claims description 15
- MCEWYIDBDVPMES-UHFFFAOYSA-N [60]pcbm Chemical compound C123C(C4=C5C6=C7C8=C9C%10=C%11C%12=C%13C%14=C%15C%16=C%17C%18=C(C=%19C=%20C%18=C%18C%16=C%13C%13=C%11C9=C9C7=C(C=%20C9=C%13%18)C(C7=%19)=C96)C6=C%11C%17=C%15C%13=C%15C%14=C%12C%12=C%10C%10=C85)=C9C7=C6C2=C%11C%13=C2C%15=C%12C%10=C4C23C1(CCCC(=O)OC)C1=CC=CC=C1 MCEWYIDBDVPMES-UHFFFAOYSA-N 0.000 claims description 14
- 238000000576 coating method Methods 0.000 claims description 13
- 239000002322 conducting polymer Substances 0.000 claims description 13
- 230000005855 radiation Effects 0.000 claims description 12
- 239000011248 coating agent Substances 0.000 claims description 11
- 239000002245 particle Substances 0.000 claims description 10
- 230000005540 biological transmission Effects 0.000 claims description 8
- XMWRBQBLMFGWIX-UHFFFAOYSA-N C60 fullerene Chemical compound C12=C3C(C4=C56)=C7C8=C5C5=C9C%10=C6C6=C4C1=C1C4=C6C6=C%10C%10=C9C9=C%11C5=C8C5=C8C7=C3C3=C7C2=C1C1=C2C4=C6C4=C%10C6=C9C9=C%11C5=C5C8=C3C3=C7C1=C1C2=C4C6=C2C9=C5C3=C12 XMWRBQBLMFGWIX-UHFFFAOYSA-N 0.000 claims description 6
- YTPLMLYBLZKORZ-UHFFFAOYSA-N Thiophene Chemical compound C=1C=CSC=1 YTPLMLYBLZKORZ-UHFFFAOYSA-N 0.000 claims description 6
- 229920000767 polyaniline Polymers 0.000 claims description 6
- VRGCYEIGVVTZCC-UHFFFAOYSA-N 3,4,5,6-tetrachlorocyclohexa-3,5-diene-1,2-dione Chemical compound ClC1=C(Cl)C(=O)C(=O)C(Cl)=C1Cl VRGCYEIGVVTZCC-UHFFFAOYSA-N 0.000 claims description 5
- BJQHLKABXJIVAM-UHFFFAOYSA-N bis(2-ethylhexyl) phthalate Chemical compound CCCCC(CC)COC(=O)C1=CC=CC=C1C(=O)OCC(CC)CCCC BJQHLKABXJIVAM-UHFFFAOYSA-N 0.000 claims description 5
- 229910003472 fullerene Inorganic materials 0.000 claims description 5
- 125000002524 organometallic group Chemical group 0.000 claims description 5
- IEQIEDJGQAUEQZ-UHFFFAOYSA-N phthalocyanine Chemical compound N1C(N=C2C3=CC=CC=C3C(N=C3C4=CC=CC=C4C(=N4)N3)=N2)=C(C=CC=C2)C2=C1N=C1C2=CC=CC=C2C4=N1 IEQIEDJGQAUEQZ-UHFFFAOYSA-N 0.000 claims description 5
- QWYZFXLSWMXLDM-UHFFFAOYSA-M pinacyanol iodide Chemical compound [I-].C1=CC2=CC=CC=C2N(CC)C1=CC=CC1=CC=C(C=CC=C2)C2=[N+]1CC QWYZFXLSWMXLDM-UHFFFAOYSA-M 0.000 claims description 5
- 229920000265 Polyparaphenylene Polymers 0.000 claims description 4
- TVIVIEFSHFOWTE-UHFFFAOYSA-K tri(quinolin-8-yloxy)alumane Chemical compound [Al+3].C1=CN=C2C([O-])=CC=CC2=C1.C1=CN=C2C([O-])=CC=CC2=C1.C1=CN=C2C([O-])=CC=CC2=C1 TVIVIEFSHFOWTE-UHFFFAOYSA-K 0.000 claims description 4
- 239000013522 chelant Substances 0.000 claims description 3
- 239000002105 nanoparticle Substances 0.000 claims description 3
- 239000006259 organic additive Substances 0.000 claims description 3
- 108091008695 photoreceptors Proteins 0.000 claims description 3
- 229930192474 thiophene Natural products 0.000 claims description 3
- UJOBWOGCFQCDNV-UHFFFAOYSA-N Carbazole Natural products C1=CC=C2C3=CC=CC=C3NC2=C1 UJOBWOGCFQCDNV-UHFFFAOYSA-N 0.000 claims description 2
- XBDYBAVJXHJMNQ-UHFFFAOYSA-N Tetrahydroanthracene Natural products C1=CC=C2C=C(CCCC3)C3=CC2=C1 XBDYBAVJXHJMNQ-UHFFFAOYSA-N 0.000 claims description 2
- HSFWRNGVRCDJHI-UHFFFAOYSA-N alpha-acetylene Natural products C#C HSFWRNGVRCDJHI-UHFFFAOYSA-N 0.000 claims description 2
- WCPAKWJPBJAGKN-UHFFFAOYSA-N oxadiazole Chemical compound C1=CON=N1 WCPAKWJPBJAGKN-UHFFFAOYSA-N 0.000 claims description 2
- 229920001197 polyacetylene Polymers 0.000 claims description 2
- 229920001088 polycarbazole Polymers 0.000 claims description 2
- 229920000128 polypyrrole Polymers 0.000 claims description 2
- 229920000123 polythiophene Polymers 0.000 claims description 2
- IFLREYGFSNHWGE-UHFFFAOYSA-N tetracene Chemical compound C1=CC=CC2=CC3=CC4=CC=CC=C4C=C3C=C21 IFLREYGFSNHWGE-UHFFFAOYSA-N 0.000 claims description 2
- 230000003213 activating effect Effects 0.000 claims 2
- 239000011810 insulating material Substances 0.000 claims 1
- 125000000843 phenylene group Chemical group C1(=C(C=CC=C1)*)* 0.000 claims 1
- 238000001514 detection method Methods 0.000 abstract description 23
- 229920000109 alkoxy-substituted poly(p-phenylene vinylene) Polymers 0.000 description 41
- 229910052751 metal Inorganic materials 0.000 description 39
- 239000002184 metal Substances 0.000 description 39
- 239000010408 film Substances 0.000 description 29
- 239000000370 acceptor Substances 0.000 description 27
- 238000005516 engineering process Methods 0.000 description 19
- 238000004519 manufacturing process Methods 0.000 description 19
- 239000000243 solution Substances 0.000 description 19
- 239000011521 glass Substances 0.000 description 18
- 238000005286 illumination Methods 0.000 description 16
- 238000013459 approach Methods 0.000 description 12
- 229920000280 Poly(3-octylthiophene) Polymers 0.000 description 11
- 230000008569 process Effects 0.000 description 11
- 239000010409 thin film Substances 0.000 description 11
- 230000006870 function Effects 0.000 description 10
- 238000000059 patterning Methods 0.000 description 10
- 230000008901 benefit Effects 0.000 description 9
- 238000001444 catalytic combustion detection Methods 0.000 description 9
- 229920000301 poly(3-hexylthiophene-2,5-diyl) polymer Polymers 0.000 description 9
- 229920001467 poly(styrenesulfonates) Polymers 0.000 description 9
- 238000012546 transfer Methods 0.000 description 9
- 238000002834 transmittance Methods 0.000 description 9
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 8
- 230000035945 sensitivity Effects 0.000 description 8
- 229910052710 silicon Inorganic materials 0.000 description 8
- 239000010703 silicon Substances 0.000 description 8
- 229910052782 aluminium Inorganic materials 0.000 description 7
- 238000010168 coupling process Methods 0.000 description 7
- 238000005859 coupling reaction Methods 0.000 description 7
- 238000009826 distribution Methods 0.000 description 7
- 150000002739 metals Chemical class 0.000 description 7
- 229920000139 polyethylene terephthalate Polymers 0.000 description 7
- 238000012545 processing Methods 0.000 description 7
- 235000012431 wafers Nutrition 0.000 description 7
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 6
- 239000011575 calcium Substances 0.000 description 6
- 238000005229 chemical vapour deposition Methods 0.000 description 6
- 230000008878 coupling Effects 0.000 description 6
- 239000007772 electrode material Substances 0.000 description 6
- 238000002474 experimental method Methods 0.000 description 6
- 229920003227 poly(N-vinyl carbazole) Polymers 0.000 description 6
- 239000007787 solid Substances 0.000 description 6
- 150000001875 compounds Chemical class 0.000 description 5
- 230000001965 increasing effect Effects 0.000 description 5
- 239000004973 liquid crystal related substance Substances 0.000 description 5
- 239000011368 organic material Substances 0.000 description 5
- 238000000206 photolithography Methods 0.000 description 5
- 229910052709 silver Inorganic materials 0.000 description 5
- 238000001429 visible spectrum Methods 0.000 description 5
- 230000000007 visual effect Effects 0.000 description 5
- 229920001609 Poly(3,4-ethylenedioxythiophene) Polymers 0.000 description 4
- 239000011149 active material Substances 0.000 description 4
- 229910021417 amorphous silicon Inorganic materials 0.000 description 4
- 238000005266 casting Methods 0.000 description 4
- 229910052802 copper Inorganic materials 0.000 description 4
- 229910052737 gold Inorganic materials 0.000 description 4
- 229920002959 polymer blend Polymers 0.000 description 4
- 239000002243 precursor Substances 0.000 description 4
- 238000006862 quantum yield reaction Methods 0.000 description 4
- 238000007650 screen-printing Methods 0.000 description 4
- 238000000926 separation method Methods 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- RFFLAFLAYFXFSW-UHFFFAOYSA-N 1,2-dichlorobenzene Chemical compound ClC1=CC=CC=C1Cl RFFLAFLAYFXFSW-UHFFFAOYSA-N 0.000 description 3
- KUJYDIFFRDAYDH-UHFFFAOYSA-N 2-thiophen-2-yl-5-[5-[5-(5-thiophen-2-ylthiophen-2-yl)thiophen-2-yl]thiophen-2-yl]thiophene Chemical compound C1=CSC(C=2SC(=CC=2)C=2SC(=CC=2)C=2SC(=CC=2)C=2SC(=CC=2)C=2SC=CC=2)=C1 KUJYDIFFRDAYDH-UHFFFAOYSA-N 0.000 description 3
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
- 239000000654 additive Substances 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 239000003945 anionic surfactant Substances 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000011161 development Methods 0.000 description 3
- 230000018109 developmental process Effects 0.000 description 3
- 230000004069 differentiation Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000005284 excitation Effects 0.000 description 3
- 229910052738 indium Inorganic materials 0.000 description 3
- AMGQUBHHOARCQH-UHFFFAOYSA-N indium;oxotin Chemical compound [In].[Sn]=O AMGQUBHHOARCQH-UHFFFAOYSA-N 0.000 description 3
- 230000000873 masking effect Effects 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 239000003960 organic solvent Substances 0.000 description 3
- 229920002848 poly(3-alkoxythiophenes) Polymers 0.000 description 3
- 238000007639 printing Methods 0.000 description 3
- 238000012552 review Methods 0.000 description 3
- 239000002904 solvent Substances 0.000 description 3
- 238000003786 synthesis reaction Methods 0.000 description 3
- 238000002207 thermal evaporation Methods 0.000 description 3
- 238000000411 transmission spectrum Methods 0.000 description 3
- 229920002799 BoPET Polymers 0.000 description 2
- CTQNGGLPUBDAKN-UHFFFAOYSA-N O-Xylene Chemical compound CC1=CC=CC=C1C CTQNGGLPUBDAKN-UHFFFAOYSA-N 0.000 description 2
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 229910052791 calcium Inorganic materials 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 239000003086 colorant Substances 0.000 description 2
- VPUGDVKSAQVFFS-UHFFFAOYSA-N coronene Chemical compound C1=C(C2=C34)C=CC3=CC=C(C=C3)C4=C4C3=CC=C(C=C3)C4=C2C3=C1 VPUGDVKSAQVFFS-UHFFFAOYSA-N 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 210000002858 crystal cell Anatomy 0.000 description 2
- JHIVVAPYMSGYDF-UHFFFAOYSA-N cyclohexanone Chemical compound O=C1CCCCC1 JHIVVAPYMSGYDF-UHFFFAOYSA-N 0.000 description 2
- 238000000151 deposition Methods 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 229920000775 emeraldine polymer Polymers 0.000 description 2
- 230000005281 excited state Effects 0.000 description 2
- RLSSMJSEOOYNOY-UHFFFAOYSA-N m-cresol Chemical compound CC1=CC=CC(O)=C1 RLSSMJSEOOYNOY-UHFFFAOYSA-N 0.000 description 2
- 229920002521 macromolecule Polymers 0.000 description 2
- 229910052749 magnesium Inorganic materials 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- 229910001092 metal group alloy Inorganic materials 0.000 description 2
- 229910044991 metal oxide Inorganic materials 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 238000005191 phase separation Methods 0.000 description 2
- 125000001997 phenyl group Chemical group [H]C1=C([H])C([H])=C(*)C([H])=C1[H] 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 102220036926 rs139866691 Human genes 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 239000000523 sample Substances 0.000 description 2
- 239000011540 sensing material Substances 0.000 description 2
- 150000003384 small molecules Chemical class 0.000 description 2
- 238000005476 soldering Methods 0.000 description 2
- 238000004528 spin coating Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 229910001887 tin oxide Inorganic materials 0.000 description 2
- QHGNHLZPVBIIPX-UHFFFAOYSA-N tin(ii) oxide Chemical class [Sn]=O QHGNHLZPVBIIPX-UHFFFAOYSA-N 0.000 description 2
- 239000008096 xylene Substances 0.000 description 2
- GKEGJNRVJZBCOX-UHFFFAOYSA-N 1-phenyl-2-[2-[2-[2-[2-(2-phenylphenyl)phenyl]phenyl]phenyl]phenyl]benzene Chemical group C1=CC=CC=C1C1=CC=CC=C1C1=CC=CC=C1C1=CC=CC=C1C1=CC=CC=C1C1=CC=CC=C1C1=CC=CC=C1C1=CC=CC=C1 GKEGJNRVJZBCOX-UHFFFAOYSA-N 0.000 description 1
- WBIQQQGBSDOWNP-UHFFFAOYSA-N 2-dodecylbenzenesulfonic acid Chemical compound CCCCCCCCCCCCC1=CC=CC=C1S(O)(=O)=O WBIQQQGBSDOWNP-UHFFFAOYSA-N 0.000 description 1
- GIFWAJGKWIDXMY-UHFFFAOYSA-N 2-octylthiophene Chemical compound CCCCCCCCC1=CC=CS1 GIFWAJGKWIDXMY-UHFFFAOYSA-N 0.000 description 1
- DWJXWSIJKSXJJA-UHFFFAOYSA-N 4-n-[4-(4-aminoanilino)phenyl]benzene-1,4-diamine Chemical compound C1=CC(N)=CC=C1NC(C=C1)=CC=C1NC1=CC=C(N)C=C1 DWJXWSIJKSXJJA-UHFFFAOYSA-N 0.000 description 1
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 1
- 229910015999 BaAl Inorganic materials 0.000 description 1
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- 239000004593 Epoxy Substances 0.000 description 1
- 241000283070 Equus zebra Species 0.000 description 1
- IAYPIBMASNFSPL-UHFFFAOYSA-N Ethylene oxide Chemical compound C1CO1 IAYPIBMASNFSPL-UHFFFAOYSA-N 0.000 description 1
- FUJCRWPEOMXPAD-UHFFFAOYSA-N Li2O Inorganic materials [Li+].[Li+].[O-2] FUJCRWPEOMXPAD-UHFFFAOYSA-N 0.000 description 1
- 229910010199 LiAl Inorganic materials 0.000 description 1
- 229920003171 Poly (ethylene oxide) Polymers 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 125000000217 alkyl group Chemical group 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 239000010405 anode material Substances 0.000 description 1
- 230000003466 anti-cipated effect Effects 0.000 description 1
- XMRUJYGYYCLRGJ-UHFFFAOYSA-N azanium;2-[2-[2-[2-(4-nonylphenoxy)ethoxy]ethoxy]ethoxy]ethyl sulfate Chemical compound [NH4+].CCCCCCCCCC1=CC=C(OCCOCCOCCOCCOS([O-])(=O)=O)C=C1 XMRUJYGYYCLRGJ-UHFFFAOYSA-N 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 239000010406 cathode material Substances 0.000 description 1
- 210000004027 cell Anatomy 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 239000002178 crystalline material Substances 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- XUCJHNOBJLKZNU-UHFFFAOYSA-M dilithium;hydroxide Chemical compound [Li+].[Li+].[OH-] XUCJHNOBJLKZNU-UHFFFAOYSA-M 0.000 description 1
- JAKJARLCPCKIFH-UHFFFAOYSA-N dodecyl benzenesulfonate tetrabutylazanium Chemical compound CCCC[N+](CCCC)(CCCC)CCCC.CCCCCCCCCCCCOS(=O)(=O)C1=CC=CC=C1 JAKJARLCPCKIFH-UHFFFAOYSA-N 0.000 description 1
- 229940060296 dodecylbenzenesulfonic acid Drugs 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000004043 dyeing Methods 0.000 description 1
- 238000004070 electrodeposition Methods 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 238000005566 electron beam evaporation Methods 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 238000000407 epitaxy Methods 0.000 description 1
- RTZKZFJDLAIYFH-UHFFFAOYSA-N ether Substances CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 239000000284 extract Substances 0.000 description 1
- 230000005669 field effect Effects 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 229920002457 flexible plastic Polymers 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 229910052736 halogen Inorganic materials 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000009396 hybridization Methods 0.000 description 1
- 238000003384 imaging method Methods 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 238000007641 inkjet printing Methods 0.000 description 1
- 150000002484 inorganic compounds Chemical class 0.000 description 1
- 229910010272 inorganic material Inorganic materials 0.000 description 1
- 229910052745 lead Inorganic materials 0.000 description 1
- 229920000763 leucoemeraldine polymer Polymers 0.000 description 1
- MCVFFRWZNYZUIJ-UHFFFAOYSA-M lithium;trifluoromethanesulfonate Chemical compound [Li+].[O-]S(=O)(=O)C(F)(F)F MCVFFRWZNYZUIJ-UHFFFAOYSA-M 0.000 description 1
- 238000010309 melting process Methods 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 238000000813 microcontact printing Methods 0.000 description 1
- 239000000178 monomer Substances 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 238000001208 nuclear magnetic resonance pulse sequence Methods 0.000 description 1
- 239000013307 optical fiber Substances 0.000 description 1
- 229920000620 organic polymer Polymers 0.000 description 1
- 230000001443 photoexcitation Effects 0.000 description 1
- 238000005240 physical vapour deposition Methods 0.000 description 1
- 239000000049 pigment Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 239000002985 plastic film Substances 0.000 description 1
- 229920000307 polymer substrate Polymers 0.000 description 1
- 229960002796 polystyrene sulfonate Drugs 0.000 description 1
- 239000011970 polystyrene sulfonate Substances 0.000 description 1
- 238000005036 potential barrier Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 230000006798 recombination Effects 0.000 description 1
- 238000005215 recombination Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- PYWVYCXTNDRMGF-UHFFFAOYSA-N rhodamine B Chemical compound [Cl-].C=12C=CC(=[N+](CC)CC)C=C2OC2=CC(N(CC)CC)=CC=C2C=1C1=CC=CC=C1C(O)=O PYWVYCXTNDRMGF-UHFFFAOYSA-N 0.000 description 1
- 229940043267 rhodamine b Drugs 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 230000001235 sensitizing effect Effects 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 229910001251 solid state electrolyte alloy Inorganic materials 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 238000004544 sputter deposition Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 239000002887 superconductor Substances 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 238000013519 translation Methods 0.000 description 1
- 239000012780 transparent material Substances 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 230000005641 tunneling Effects 0.000 description 1
- 238000007738 vacuum evaporation Methods 0.000 description 1
- 238000007740 vapor deposition Methods 0.000 description 1
- 229910052727 yttrium Inorganic materials 0.000 description 1
- 235000014692 zinc oxide Nutrition 0.000 description 1
- RNWHGQJWIACOKP-UHFFFAOYSA-N zinc;oxygen(2-) Chemical class [O-2].[Zn+2] RNWHGQJWIACOKP-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K30/00—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation
- H10K30/451—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation comprising a metal-semiconductor-metal [m-s-m] structure
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y10/00—Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
- H01L27/144—Devices controlled by radiation
- H01L27/146—Imager structures
- H01L27/14643—Photodiode arrays; MOS imagers
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K10/00—Organic devices specially adapted for rectifying, amplifying, oscillating or switching; Organic capacitors or resistors having potential barriers
- H10K10/50—Bistable switching devices
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K30/00—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation
- H10K30/20—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation comprising organic-organic junctions, e.g. donor-acceptor junctions
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K30/00—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation
- H10K30/30—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation comprising bulk heterojunctions, e.g. interpenetrating networks of donor and acceptor material domains
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K39/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic radiation-sensitive element covered by group H10K30/00
- H10K39/30—Devices controlled by radiation
- H10K39/32—Organic image sensors
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
- H10K85/10—Organic polymers or oligomers
- H10K85/111—Organic polymers or oligomers comprising aromatic, heteroaromatic, or aryl chains, e.g. polyaniline, polyphenylene or polyphenylene vinylene
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y20/00—Nanooptics, e.g. quantum optics or photonic crystals
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
- H10K85/10—Organic polymers or oligomers
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
- H10K85/10—Organic polymers or oligomers
- H10K85/111—Organic polymers or oligomers comprising aromatic, heteroaromatic, or aryl chains, e.g. polyaniline, polyphenylene or polyphenylene vinylene
- H10K85/113—Heteroaromatic compounds comprising sulfur or selene, e.g. polythiophene
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
- H10K85/10—Organic polymers or oligomers
- H10K85/111—Organic polymers or oligomers comprising aromatic, heteroaromatic, or aryl chains, e.g. polyaniline, polyphenylene or polyphenylene vinylene
- H10K85/113—Heteroaromatic compounds comprising sulfur or selene, e.g. polythiophene
- H10K85/1135—Polyethylene dioxythiophene [PEDOT]; Derivatives thereof
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
- H10K85/10—Organic polymers or oligomers
- H10K85/111—Organic polymers or oligomers comprising aromatic, heteroaromatic, or aryl chains, e.g. polyaniline, polyphenylene or polyphenylene vinylene
- H10K85/114—Poly-phenylenevinylene; Derivatives thereof
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
- H10K85/10—Organic polymers or oligomers
- H10K85/111—Organic polymers or oligomers comprising aromatic, heteroaromatic, or aryl chains, e.g. polyaniline, polyphenylene or polyphenylene vinylene
- H10K85/115—Polyfluorene; Derivatives thereof
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
- H10K85/10—Organic polymers or oligomers
- H10K85/141—Organic polymers or oligomers comprising aliphatic or olefinic chains, e.g. poly N-vinylcarbazol, PVC or PTFE
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
- H10K85/10—Organic polymers or oligomers
- H10K85/141—Organic polymers or oligomers comprising aliphatic or olefinic chains, e.g. poly N-vinylcarbazol, PVC or PTFE
- H10K85/143—Polyacetylene; Derivatives thereof
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
- H10K85/20—Carbon compounds, e.g. carbon nanotubes or fullerenes
- H10K85/211—Fullerenes, e.g. C60
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
- H10K85/30—Coordination compounds
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
- H10K85/30—Coordination compounds
- H10K85/311—Phthalocyanine
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
- H10K85/30—Coordination compounds
- H10K85/321—Metal complexes comprising a group IIIA element, e.g. Tris (8-hydroxyquinoline) gallium [Gaq3]
- H10K85/324—Metal complexes comprising a group IIIA element, e.g. Tris (8-hydroxyquinoline) gallium [Gaq3] comprising aluminium, e.g. Alq3
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
- H10K85/60—Organic compounds having low molecular weight
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/549—Organic PV cells
Definitions
- the present invention relates to organic, polymer-based photodiodes and to their use in one and two dimensional image sensors.
- it concerns organic polymer-based photodiodes which are voltage switchable and which may be arrayed as image sensors in the form of a column-row (x-y) passively addressable matrix, where the x-y addressable organic image sensors (image arrays) have fall-color or selected-color detection capability, or as linear photodiode arrays.
- image array photodetectors has a relatively long history in the solid state device industry. Early approaches to imaging technology included devices based on thermal effects in solid state materials. These were followed by high sensitivity image arrays and matrices based on photodiodes and charge-coupling devices (“CCDs”) made with inorganic semiconductors. These arrays can be simple linear (or “one dimensional”) arrays which scan an image or they can be two dimensional, like the image.
- CCDs charge-coupling devices
- An “x-y” matrix is a two dimensional array with a first set of electrodes perpendicular to a second set of electrodes.
- the matrix is often called a “passive” matrix in contrast to an “active” matrix in which active devices, such as transistors, are used to control the turn-on for each pixel.
- the pixel elements must exhibit strongly nonlinear current-voltage (“I-V”) characteristics or an I-V dependence with a threshold voltage. This requirement provides the foundation for using light-emitting diodes or liquid crystal cells to construct passive x-y addressable displays.
- I-V current-voltage
- the photoresponse of inorganic photodiodes is voltage-independent in reverse bias, photodiodes made with inorganic semiconductor crystals are not practical for use in high pixel density, passive image sensors—there is too much cross-talk between pixels.
- CCD arrays are integrated devices. They are different than x-y addressable matrix arrays.
- the operating principle of CCDs involves serial transfer of charges from pixel to pixel. These interpixel transfers occur repeatedly and result in the charge migrating, eventually, to the edge of the array for read-out.
- SLIC super-large integrating circuit
- the thin film transistor (“TFT”) technology on glass or quartz substrates which was developed originally for the needs of liquid crystal displays, can provide active-matrix substrates for fabricating large size, x-y addressable image sensors.
- TFT thin film transistor
- a large size, full color image sensor made with amorphous silicon (a-Si) p-i-n photocells on a-Si TFT panels was demonstrated recently [R. A. Street, J. Wu, R. Weisfield, S. E. Nelson and P. Nylen, Spring Meeting of Materials Research Society, San Francisco, Apr. 17-21 (1995); J. Yorkston et al., Mat. Res. Soc. Sym. Proc. 116, 258 (1992); R. A.
- CCDs, a-Si TFTs, and active-pixel CMOS image sensors represent the existing/emerging technologies for solid state image sensors.
- SLIC technologies because of the costly processes involved in fabrication of these sophisticated devices, their applications are severely limited.
- SLIC technologies in the fabrication processes limits the CCDs and the active-pixel CMOS sensors to sub-inch device dimensions.
- Photodiodes made with organic semiconductors represent a novel class of photosensors with promising process advantages. Although there were early reports, in the 1980s, of fabricating photodiodes with organic molecules and conjugated polymers, relatively small photoresponse was observed [for an review of early work on organic photodiodes, see: G. A. Chamberlain, Solar Cells 8, 47 (1983)]. In the 1990s, there has been progress using conjugated polymers as the active materials; see for example the following reports on the photoresponse in poly(phenylene vinylene), PPV, and its derivatives,: S. Karg, W. Riess, V. Dyakonov, M. Schwoerer, Synth.
- the photosensitivity in organic semiconductors can be enhanced by excited-state charge transfer; for example, by sensitizing the semiconducting polymer with acceptors such as C 60 or its derivatives [N. S. Saricifici and A. J. Heeger, U.S. Pat. No. 5,331,183 (Jul. 19, 1994); N. S. Saricifici and A. J. Heeger, U.S. Pat. No. 5,454,880 (Oct. 3, 1995); N. S. Sariciftci, L. Smilowitz, A. J. Heeger and F. Wudl, Science 258, 1474 (1992); L. Smilowitz, N. S. Sariciftci, R. Wu, C.
- acceptors such as C 60 or its derivatives
- Photoinduced charge transfer prevents early time recombination and stabilizes the charge separation, thereby enhancing the carrier quantum yield for subsequent collection [B. Kraabel, C. H. Lee, D. McBranch, D. Moses, N. S. Sariciftci and A. J. Heeger, Chem. Phys. Lett. 213, 389 (1993); B. Kraabel, D. McBranch, N. S. Sariciftci, D. Moses and A. J.
- the photosensitivity of thin film photodiodes made with polymer charge transfer blends is comparable to that of photodiodes made with inorganic semiconducting crystals.
- these organic photodiodes show large dynamic range; relatively flat photosensitivity has been reported from 100 mW/cm 2 down to nW/cm 2 ; i.e., over eight orders of magnitude [G. Yu, H. Pakbaz and A. J. Heeger, Appl. Phys. Lett. 64, 3422 (1994); G. Yu, J. Gao, J. C. Hummelen, F. Wudl and A. J. Heeger, Science 270, 1789 (1995); G. Yu and A. J.
- the polymer photodetectors can be operated at room temperature, and the photosensitivity is relatively insensitive to the operating temperature, dropping by only a factor of 2 from room temperature to 80 K [G. Yu, K. Pakbaz and A. J. Heeger, Appl. Phys. Lett. 64, 3422 (1994)].
- polymer light-emitting devices [G. Gustafsson, Y. Cao, G. M. Treacy, F. Klavetter, N. Colaneri, and A. J. Heeger, Nature 357, 477 (1992); A. J. Heeger and J. Long, Optics & Photonics News, Aug. 1996, p.24]
- high sensitivity polymer photodetectors can be fabricated in large areas by processing from solution at room temperature. They can be made in unusual shapes (e.g. on a hemisphere to couple with an optical component or an optical system), or they can be made in flexible or foldable forms. The processing advantages also enable one to fabricate the photosensors directly onto optical fibers.
- polymer photodiodes can be hybridized with optical devices or electronic devices, such as an integrated circuits on a silicon wafer. These unique features make polymer photodiodes special for many novel applications.
- this variable photosensitivity enables on-off voltage-switchable photosensors.
- a reverse bias typically in the range of 2-15 V
- the photodiode can be switched on with photosensitivity of 30-300 mA/W.
- the photosensitivity at a voltage close to the internal (built-in) potential is several orders of magnitude lower, equivalent to zero at the output of a digital read-out circuit. This near zero state can thus be defined as the off state of the photodiode.
- These voltage-switchable, organic photodiodes can serve as individual pixels in passive diode arrays. These arrays can be in the form of x-y addressable arrays with anodes connected via row (column) electrodes and cathodes connected via column (row) electrodes. Every pixel can be selected, and the information (intensity of the incident light) at each pixel can be read out without crosstalk. Alternatively, the voltage-switchable, organic photodiodes can be arrayed in a linear manner.
- These arrays can utilize the processing advantages associated with the fabrication of organic diode structures from soluble, semiconducting, conjugated polymers (and/or their precursor polymers). Layers of these materials can be cast from solution to enable the fabrication of large active areas, onto substrates with desired shapes. This also enables active areas to be in flexible form. These photoactive materials can be patterned onto an optically uniform substrate by means of photolithography, microcontact printing, shadow masking and the like. In a preferred embodiment for the visible region of the spectrum, the substrate is opaque for ⁇ 400 nm so that the pixels are insensitive to UV radiation.
- the photoactive layer employed in these switchable photodiodes is made up of organic materials. These take numerous forms. They can be conjugated semiconducting polymers or polymer blends.
- the acceptor can be a polymer, macromolecule, oligomer or small molecule (monomers). Alternatively, molecular donor/polymeric acceptor systems also work well. The higher molecular weight component in many cases provides mechanical strength and prevents phase changes.
- the donor-acceptor blends can also be made with small molecule donors and acceptors that are well known in the art.
- Examples of the molecular and oligomeric donors include anthracene and its derivatives, pinacyanol and its derivatives thiophene oligomers (such as sexithiophene.6T, and octylthiophene, 8T) and their derivatives and the like, phenyl oligomers (such as sexiphenyl or octylphenyl) and the like.
- Examples of molecular acceptors include fullerenes (such as C 60 and their functional derivatives), Alq 3 -type organometallic molecules and the like.
- the organic image sensors enabled by this invention can have mono-color or multi-color detection capability.
- color (optical wavelength) selection can be achieved by combining a suitable color filter panel with the organic image sensors and image sensor arrays already described. If desired, the color filter panel can serve as a substrate upon which the image sensor is carried.
- the detection wavelength of the organic image sensors can also be selected by using resonant cavity device structures as demonstrated in the examples of the invention.
- the organic image sensor arrays with the ability to select specific wavelengths can be used for spectrographic applications (such as flat-panel spectrometers).
- a filter panel is made up of red, green and blue color filters which are patterned in a format corresponding to the format of a photodiode array.
- the panel of patterned filters and the patterned photodiode array are coupled (and coordinated) such that a colored image sensor is formed.
- the patterned color filter panel can be used directly as the substrate of the image sensor.
- Full-color detectivity is also achieved when red, green and blue colors are detected by three of these photodiodes with spectral response cut-off at 500 nm, 600 nm and 700 nm, respectively. Differentiation operations in the read-out circuit extract the red (600-700 nm), green (500-600 nm) and blue (400-500 nm) signals.
- FIG. 1 is a cross-sectional schematic view of a voltage-switchable photodiode of this invention 10 assembled into a circuit.
- the photocurrent can be read out by a current meter or a read-out device inserted in the loop;
- FIG. 2 is a cross-sectional schematic view of a voltage-switchable photodiode 20 in reversed configuration, in which the reversed configuration refers the structure with the transparent electrode contacted with the free surface of the active layer;
- FIG. 3 is an exploded schematic view of a 2D image sensor 30 made of an x-y addressable, passive matrix of voltage-switchable photodiodes;
- FIG. 4 is an exploded schematic view of a full-color image sensor 40 made with an x-y addressable photodiode matrix coupled to a color filter panel;
- FIG. 5 is an exploded schematic view of a full-color image sensor 50 made with an x-y addressable photodiode matrix of which each full-color pixel is made of three photosensitive materials having differing long-wavelength cut-offs such as at 700 nm, 600 nm and 500 nm;
- FIG. 6 is a graph of the photocurrent as a function of bias voltage in a ITO/MEH-PPV/Ca device
- FIG. 7 is a graph of the transmission characteristics of PANI-CSA and PEDT-PSSA conducting polymer electrodes; also shown is the visual response, V( ⁇ ), of human eye.
- FIG. 8 is a graph of the photocurrent (circles) and the dark current (solid line) of a ITO/MEH-PPV:PCBM/Al photodiode.
- the photocurrent was taken under white light of intensity ⁇ 10 mW/cm 2 .
- FIG. 9 is a graph of the current-voltage characteristics of an ITO/P3OT/Au photodiode in the dark (circles), and illuminated under ⁇ 10 mW/cm at 633 nm (squares);
- FIG. 10 is a graph of the current-voltage characteristics measured between a row electrode and a column electrode from a 7 ⁇ 40 photodiode matrix in the dark (lines) and under room light illumination (circles);
- FIG. 11 is a schematic representation of the driving scheme for a 7 ⁇ 40 photodiode matrix. It will be described in terms of ITO/MEH-PPV:PCBM/Ag switchable photodiodes;
- FIG. 12 is a graph of the photoresponse of a voltage-switchable photodiode made with P3OT;
- FIG. 13A is a graph of the photoresponse of voltage-switchable photodiodes with spectral response simulating that of human eye, V( ⁇ );
- FIG. 13B is a graph of the transmittance of the long-wavelength-pass filter and the visual response, V( ⁇ ) corresponding to FIG. 13A;
- FIG. 14 is a graph of the spectral response of a solar blind UV detector operating at ⁇ 2V. The photoresponse of the MEH-PPV:C 60 photodiode on ITO/glass substrate and the photoresponse of an UV-enhanced Si photodiode are plotted for comparison;
- FIG. 15A is a graph of the response of a PTV photodiode
- FIG. 15B is a graph of the photoresponse of R, G, B photosensors made of PTV photodiodes coupled with a color-filter panel;
- FIG. 15C is a graph of the transmittance of the color filters used in the generation of the data graphed in FIGS. 15A and 15B;
- FIG. 16A is a graph of normalized spectral response of photodiodes made with PPV (open squares), PDHPV (open circles), and PTV (solid circles);
- FIG. 16B is a graph of red, green and blue color detection derived from the diode responses in FIG. 16A;
- FIG. 17 is a graph showing I-V response of a photodiode made with PPV in the dark and under illumination
- FIG. 18 is a graph showing I-V response of a photodiode with a donor/acceptor heterojunction structure in the dark and under illumination;
- FIG. 19 is a graph of the dark (solid circles) and photocurrents (circles) of a P3HT photodiode under 8 mW/cm 2 broad band white light (400-700 nm);
- FIGS. 20A and 20B are cross-sectional schematic views of linear photodiode arrays made with organic semiconductors
- FIG. 21 is a sketch of the circuit used to drive the organic photodiode array
- FIGS. 22 A-D show images achieved by a P30T linear photodiode array of 100 pixels over a 2.5 inch length.
- FIG. 22A is a red color image
- FIG. 22B is a green color image
- FIG. 22C is a blue color image
- FIG. 22D is a full-color image recovered by superposing the red, green and blue color images of FIGS. 22 A-C;
- FIG. 23 is a graph of an optical beam analyzer made with a 1 ⁇ 102 polymer photodiode array
- FIG. 24 is a graph of the angular distribution of the light emission from a GaP LED measured with a flexible linear photodiode array
- FIG. 25 is a schematic view of a spectrographer made of P30T photodiode array
- FIG. 26 is a graph of the transmission spectra of a PPV film measured with the spectrographer of FIG. 25.
- FIG. 27 is a graph of the spectral response of an organic photosensor in microcavity (optic etalon) structure.
- This invention provides high sensitivity photodiodes with voltage-switchable photosensitivity; the photosensitivity can be switched on and off by the application of selected voltages, thereby reducing cross-talk between pixels in an array of such voltage-switchable photodiodes to acceptable levels.
- These switchable photosensors enable the fabrication of either one- or two-dimensional (2D), passive image sensors with column-row (x-y) addressability.
- the voltage-switchable photodetector is constructed in a metal-semiconductor-metal (M-S-M) thin film structure in which an organic film such as a film of semiconducting polymer or a polymer blend is used as the photoactive material.
- Selected-color or multi-color detection in the visible and near UV can be achieved by coupling the image sensor to an optical filter(s). Fabrication processes for red, green and blue (RGB) and full-color image sensors are described by coupling the x-y addressable polymer diode matrix or linear array with a RGB color filter panel, or by fabricating photodiodes with cut-off of the photoresponse at 500 nm, 600 nm and 700 nm, respectively, onto optically uniform substrates, or by fabricating the photodiodes in microcavity structures with defined spectral responses in the red, green and blue regions.
- RGB red, green and blue
- Voltage-switchable photodiodes make possible 2D image sensors.
- a 2D x-y addressable, passive image sensor can be constructed which operates without crosstalk.
- a column of pixels in the 2D photodiode matrix can be selected and turned on with proper voltage bias, leaving the rest of the pixels on other rows insensitive to the incident light.
- the physical M row, N column 2D matrix is reduced to N isolated linear diode arrays each with M elements; said isolated linear diode arrays are free from the crosstalk which originates from finite resistance between devices on different columns.
- an image can be read out with a pulse train scanning through each column of the matrix. Since the number of contact electrodes are reduced to N+M in the x-y addressable matrix, compared to N ⁇ M in the case of individual connection, large size, high pixel density, 2D image arrays become practical (comparable to the high pixel density display arrays made with LCD technology). For example, for a 1000 by 1000 pixel array, the present invention reduces the number or required electrodes by 500 times.
- the polymer image sensor matrix thus provides a unique approach to fabricating large size, low cost, high pixel density, 2D image sensing arrays with a room temperature manufacturing process.
- these voltage-switchable organic photosensors can also be used to construct linear photodiode arrays.
- the ratio of I ph (V on )/I ph (V off ) can be more than 3 ⁇ 10 7 under photoexcitation of a few mW/cm 2 .
- the large I ph (V on )/I dark (V on ) ratio (>1.3 ⁇ 10 5 ) allows the collection of image data with gray scale resolution of more than 12 bits (12 bit has 4096 gray levels).
- Linear photodiode arrays made with these materials can be used for high image quality (over 18 bits), full-page color digital image scanners. Contrary to active image sensors, no analog switches are needed to drive these arrays.
- a digital shift register or a BCD decoder can be used for pixel selection.
- the device structure of the linear photodiode array is shown in FIG. 19.
- Transparent glass or PET films can be used as the substrates.
- Opaque materials such as silicon wafers can also be used as the substrate material. In this case, the light is incident onto the free surface side as shown in FIG. 19B.
- the linear diode array can be made in flexible form.
- Optical devices with curved surface can also be used as the substrate for these diode arrays; i.e., the linear diode array can be coupled to and integrated with other optical devices in a desired optical arrangement and with a desired optical wavefront.
- Linear photodiode arrays can be made in the configurations similar to that shown in FIG. 3 with one row and n columns or with one column and n rows.
- the cross sectional views of two typical device structures are shown in FIG. 19.
- the substrates can be transparent or opaque.
- the linear photodiode arrays ( 210 ) can be fabricated onto a transparent glass substrate ( 214 ) with patterned ITO ( 211 ) or other transparent electrode materials (such as conducting polymer electrodes, thin metal films, metal/conducting polymer bilayer electrodes dielectric film/ITO or metal film/dielectric film bilayer electrodes).
- ITO patterned transparent glass substrate
- other transparent electrode materials such as conducting polymer electrodes, thin metal films, metal/conducting polymer bilayer electrodes dielectric film/ITO or metal film/dielectric film bilayer electrodes.
- the process of ITO patterning is well known in the existing art, and has been used broadly in LCD technologies.
- the deposition of the organic layer ( 212 ) can be achieved by spin casting, drop casting, printing, electrochemical synthesis or vapor deposition.
- the back electrode, in the form of a narrow bar shape ( 213 ) can be vacuum deposited with a simple shadow mask or patterned by means of photolithography. In most applications (especially for larger pixel sizes), no patterning of the sensing material is necessary.
- This sensing array can be mounted onto a print circuit (PC) board with a driving circuit.
- PC print circuit
- Several existing connection techniques such as card-edge connectors, zebra connectors, bonding tapes, wire bonding, soldering bumper etc.
- the drive circuits can also be arranged (surrounding the sensor array) onto the same substrate.
- the IC chips can be bonded to the glass substrate, and the electrical connections can be achieved via soldering, one-dimensional conducting epoxy or other existing connection technologies.
- the spectral response of the polymer image sensors can cover the entire visible spectrum with relatively flat response.
- a portion of the visible spectrum can also be selected with a band-pass or low-pass optical filter.
- Multi-color detection in the visible and the near UV can be achieved by coupling the image sensor with a color-filter panel.
- a fabrication process for full-color image sensors is described with the x-y addressable polymer diode matrix and a RGB (red, green, blue) color filter panel.
- RGB red, green, blue
- the voltage-switchable photodiode 10 is constructed using the metal-semiconductor-metal (M-S-M) thin film device configuration. Specifically, the device 10 includes:
- a “photoactive layer” (layer 12 ) comprised of organic, semiconducting material(s), such as a conjugated polymer, a polymer blend, a polymer/molecule polyblend, a layer of organic molecule or molecular blends; or a multilayer structure combining the above materials;
- Two “contact electrodes” (layers 11 , 13 ) which serve as the anode and cathode of the photodiodes to extract electrons and holes, respectively, from the photoactive layer.
- One of the electrodes (layer 11 in FIG. 1) is made transparent or semitransparent in the spectral range of interest to allow the incident light 18 to be absorbed in the active layer ( 12 ).
- the “anode” electrode is defined as a conducting material with higher work function than the “cathode” material.
- Electrodes 11 and 13 are connected to bias voltage source 15 via lines 17 and 17 ′, respectively.
- Detector 16 (that represents a current meter or a read out device) is wired in series into this circuit to measure the photoresponse generated in the photodiode in response to light 18 .
- This same circuit would be employed in all of the devices ( 10 , 20 , 30 , 40 and 50 ) depicted in FIGS. 1 - 5 .
- the devices may also include an optional substrate or support 14 , as shown in FIGS. 1 - 5 .
- This is a solid, rigid or flexible layer designed to provide robustness to the diodes and/or to the matrix array of diodes.
- the substrate When light is incident from the substrate side, the substrate should be transparent or semitransparent in the spectral range of interest. Glass, polymer sheets or flexible plastic films are substrates commonly used. Wide band semiconductor wafers (such as SiC, SiN) which are transparent below their optical gaps can also be used in some applications. In these cases, a thin, doped region can also serve as the contact electrode 11 .
- Devices with the inverted geometry shown in FIG. 2 are also useful in applications.
- light 18 is incident from the “back” electrode side, and optically opaque materials can be used as the substrate material.
- an inorganic semiconductor wafer such as silicon
- the wafer can serve both as the substrate 14 and the contact electrode 11 .
- the inverted structure offers the advantage of integrating the photosensor with driving/read-out circuitry built directly onto the inorganic semiconductor substrate (using integrated circuit technology).
- the incident light 18 is defined generally so as to include wavelengths in visible (400-700 mn), wavelengths in the ultraviolet (200-400 nm), wavelength in the vacuum UV ( ⁇ 200 mn), and wavelengths in the infrared (700-2000 nm).
- transparent or “semi-transparent”. These terms are used to refer to the property of a material which transmits a substantial portion of the incident light incident on it.
- transparent is used to describe a substrate with transmittance over 50% and the term “semi-transparent” is used to describe a substrate with transmittance between 50% to 5%.
- a “conductive” layer or material has a conductivity typically larger than 0.1 S/cm.
- a semiconducting material has conductivity of from 10 ⁇ 14 to 10 ⁇ 1 S/cm.
- the “positive” (or “negative”) bias refers to the cases when higher potential is applied to the anode electrode (cathode electrode).
- values of negative voltage are referred to, as in the case of the reverse bias voltages applied to obtain enhanced photosensitivity, the relative values will be stated in terms of absolute values; that is, for example, a ⁇ 10 V (reverse) bias is greater than a ⁇ 5 V (reverse) bias.
- FIG. 3 The structure of the x-y addressable, passive photodiode matrix (2D image sensor 30 ) is depicted in FIG. 3. Shown in FIG. 4 is the structure of a full-color image sensor 40 made with the x-y addressable photodiode matrix.
- the anode and cathode electrodes 11 ′, 13 ′ are typically patterned into rows and columns perpendicular to one another. Patterning of the photoactive layer 13 is not necessary for pixels with sufficient space between adjacent electrodes.
- Each intersection of the row and column electrodes defines a photosensitive element (pixel) with device structure similar to that shown in FIG. 1 or FIG. 2.
- the widths of the row and column electrodes 11 ′, 13 ′ define the active area of each pixel.
- a matrix of color filters 19 (each pixel of the color filter is comprised of red, green and blue color filters 19 ′) is coupled with the photodiode panel.
- a separate sheet of color filters similar to that used for color-LCD displays [For a review, see: M. Tani and T. Sugiura, Proceeding of SID, Orlando, Fla. (1994)] can be used for this purpose.
- the color-filter panel can be coated directly onto the substrate for the photodiode matrix.
- the set of transparent electrodes 11 (for example, made of indium-tin-oxide, ITO) can be fabricated over the color filter coating. In this configuration, high pixel densities with micron-size feature size can be achieved.
- a coating of “black” material (opaque in the spectral range of interest) in the area between each sensing pixel can be placed in front of the photodetector plane, forming a “black matrix”. This coating is helpful in some situations to further reduce cross-talk between neighbor pixels in devices with an unpatterned photoactive organic layer.
- Black matrices have been used in CRT monitors and other flat panel displays to increase display contrast, and are well known in the display industry.
- the patterning of the “black matrix” can be achieved with standard photolithography, stamp, ink-jet or screen printing techniques.
- each full-color pixel 12 ′ comprises three photodiodes 12 R, 12 G and 12 B with long wavelength cut-offs at 700, 600 and 500 nm, respectively. These photodiodes are made of three photosensitive materials in the defined areas on the substrate.
- the patterning of the active layers can be achieved by photolithography, screen printing, shadow masking and the like.
- the correct red, green and blue color information can be obtained by differentiation of the signals (in the read-out circuit) from the three sub-pixels, 12 R, 12 G and 12 B, as demonstrated in the examples of this invention.
- An optically uniform material is used as the substrate which is transparent in the visible and opaque in UV.
- the color selection can also be achieved by combining the device structure shown in FIG. 4 with that shown in FIG. 5. For instance, with the photosensing material in the photodiode defining part of the spectral response, the optical filter placed in front fine-tunes the response desired.
- Example 15 utilizes this approach for a photosensor simulating the response of the human eye.
- the photoactive layer 12 in the voltage-switchable photodiodes is made of a thin sheet of organic semiconducting material.
- the active layer can comprise one or more semiconducting, conjugated polymers, alone or in combination with non-conjugated materials, one or more organic molecules, or oligomers.
- the active layer can be a blend of two or more conjugated polymers with similar or different electron affinities and different electronic energy gaps.
- the active layer can be a blend of two or more organic molecules with similar or different electron affinities and different electronic energy gaps.
- the active layer can be a blend of conjugated polymers and organic molecules with similar or different electron affinities and different energy gaps.
- the active layer can also be a series of heterojunctions utilizing layers of organic materials or blends as indicated above.
- the thin films of organic molecules, oligomers and molecular blends can be fabricated with thermal evaporation, chemical vapor deposition (CVD) and so on.
- Thin films of conjugated polymers, polymer/polymer blends, polymer/oligomer and polymer/molecule blends can often be fabricated by casting directly from solution in common solvents or using similar fluid phase processing.
- the devices can be fabricated onto flexible substrates yielding unique, mechanically flexible photo sensors.
- Examples of typical semiconducting conjugated polymers include, but are not limited to, polyacetylene, (“PA”), and its derivatives; polyisothianaphene and its derivatives; polythiophene, (“PT”), and its derivatives; polypyrrole, (“PPr”), and its derivatives; poly(2,5-thienylenevinylene), (“PTV”), and its derivatives; poly(p-phenylene), (“PPP”), and its derivatives; polyflourene, (“PF”), and its derivatives; poly(phenylene vinylene), (“PPV”), and its derivatives; polycarbazole and its derivatives; poly(1,6-heptadiyne); polyisothianaphene and its derivatives; polyquinolene and semiconducting polyanilines (i.e.
- leucoemeraldine and/or the emeraldine base form leucoemeraldine and/or the emeraldine base form.
- Representative polyaniline materials are described in U.S. Pat. No. 5,196,144 which is incorporated herein by reference. Of these materials, those which exhibit solubility in organic solvents are preferred because of their processing advantages.
- Examples of PPV derivatives which are soluble in common organic solvents include poly(2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene), (“MEH-PPV”) [F. Wudl, P. -M. Allemand, G. Srdanov, Z. Ni and D. McBranch, in Materials for Nonlinear Optics: Chemical Perspectives, edited by S. R. Marder, J. E. Sohn and G. D. Stucky (The American Chemical Society, Washington D.C., 1991), p.
- soluble PTs include poly(3-alkylthiophenes), (“P3AT”), wherein the alkyl side chains contain more than 4 carbons, such as from 5 to 30 carbons.
- Organic image sensors can be fabricated using donor/acceptor polyblends as the photoactive layer. These polyblends can be blends of semiconducting polymer/polymer, or blends of semiconducting polymer with suitable organic molecules and/or organometallic molecules. Examples for the donor of the donor/acceptor polyblends include but are not limited to the conjugated polymers just mentioned, that is PPV, PT, PTV, and poly(phenylene), and their soluble derivatives.
- acceptors of the donor/acceptor polyblends include but are not limited to poly(cyanaophenylenevinylene) (“CN-PPV”), fullerene molecules such as C 60 and its functional derivatives, and organic molecules and organometallic molecules used heretofore in the art for photoreceptors or electron transport layers.
- CN-PPV poly(cyanaophenylenevinylene)
- fullerene molecules such as C 60 and its functional derivatives
- organic molecules and organometallic molecules used heretofore in the art for photoreceptors or electron transport layers.
- the donor layer is typically a conjugated polymer layer and the acceptor layer is made up of poly(cyanaophenylenevinylene) (“CN-PPV”), fullerene molecules such as C 60 and its functional derivatives (such as PCBM and PCBCR), or organic molecules used heretofore in the art for photoreceptors and electron transport layers.
- CN-PPV poly(cyanaophenylenevinylene)
- fullerene molecules such as C 60 and its functional derivatives (such as PCBM and PCBCR)
- organic molecules used heretofore in the art for photoreceptors and electron transport layers examples include but are not limited to, PPV/C 60 , MEH-PPV/C 60 , PT/C 60 , P3AT/C 60 , PTV/C 60 and so on.
- the active layer can also be made of wide band polymers such as poly-N-vinylcarbazole (“PVK”) doped with dye molecule(s) to enhance photosensitivity in the visible spectral range.
- the wide band organic serves as both host binder as well as hole (or electron) transport material. Examples include, but are not limited to, PVK/o-chloranil, PVK/rhodamine B and PVK/coronene and the like.
- the photoactive layer can employ organic molecules, oligomers or molecular blends.
- the photosensitive material can be fabricated into thin films by chemical vapor deposition, molecular epitaxy or other known film-deposition technologies.
- suitable materials include but are not limited to include anthracene and its derivatives, tetracene and its derivatives, phthalocyanine and its derivatives, pinacyanol and its derivatives, fullerene (“C 60 ”) and its derivatives, thiophene oligomers (such as sixethiophene “6T” and octithiophene “8T”) and their derivatives phenyl oligomers (such as sixephenyl “6P” or octiphenyl “8P”) and their derivatives, aluminum chelate (Alq3) and other metal-chelate molecules (m-q3), PBD, spiro-PBD, oxadiazole and its derivatives and blends such as 6T/
- the active layer comprises one or more organic additives (which are optically non-active) to modify and to improve the device performance.
- organic additives which are optically non-active
- the additive molecules include anionic surfactants such as ether sulfates with a common structure,
- R represents alkyl alkyllaryl
- M + represents proton, metal or ammonium counterion
- additives include solid state electrolytes or organic salts. Examples include poly(ethylene oxide), lithium trifluoromethanesulfonate, or their blends, tetrabutylammonium dodecylbenzenesulfonate and the like. Application of such electrolyte to luminescent polymers and invention of new type of light-emitting devices have been demonstrated in U.S. Pat. Nos. 5,682,043 and 5,677,546.
- the active layer is made of organic blends with two or more phases with different electron affinities and optical energy gaps, nanoscale phase separation commonly occurs, and heterojunctions form at the interfacial area.
- the phase(s) with higher electron affinity acts as an electron acceptor(s) while the phases with lower electron affinity (or lower ionization energy serves as an electron donor(s).
- These organic blends form a class of charge-transfer materials, and enable the photo-initiated charge separation process defined by the following steps [N. S. Sariciftci and A. J. Heeger, Intern. J. Mod. Phys. B 8, 237 (1994)]:
- Step 1 D+A′′ 1,3 D*+A, (excitation on D);
- Step 2 1,3 D*+A′′ 1,3 (D ⁇ A)*, (excitation delocalized on D ⁇ A complex);
- Step 3 1,3 (D ⁇ A)*′′ 1,3 (D d+ ⁇ A d ⁇ )*, (charge transfer initiated);
- Step 4 1,3 (D d+ ⁇ A d ⁇ )*′′ 1,3 (D +° ⁇ A ⁇ ° ), (ion radical pair formed);
- Step 5 1,3 (D +° ⁇ A ⁇ ° )′′D +° +A ⁇ ° , (charge separation)
- the active film thicknesses are not critical, device performance can typically be improved by using thinner films with optical densities of less than two in the spectral region of interest.
- the organic photodiodes of this invention are constructed in an M-S-M structure, in which the organic photoactive layer is bounded on two sides with conductive contact electrodes.
- a transparent substrate 14 and a transparent electrode 11 are used as one contact electrode.
- Indium-tin-oxides (“ITO”) can be used as the electrode 11 .
- Other transparent electrode materials include aluminum doped zinc oxides (“AZO”), aluminum doped tin-oxides (“ATO”), tin-oxides and the like. These conducting coatings are made of doped metal-oxide compounds which are transparent from near UV to mid-infrared.
- the electrode 11 can also be made with other doped inorganic compounds or alloys. These compounds can be doped into metallic (or near metallic) form by varying the composition of the elements involved, the valance of the elements or the morphology of the films. These semiconducting or metallic compounds are known in the art and are well documented (e.g., N. F. Mott, Metal-Insulating Transitions, 2nd edition (Taylor & Francis, London, 1990); N. F. Mott and E. A. Davis, Electronic Processes in Non-crystalline Materials (Claredon, Oxford, 1979)]. Examples of such compounds include the cuprate materials which possess superconductivity at low temperatures (so-called high temperature superconductors).
- the electrode 11 in FIG. 1 can be formed of a conductive polymer such as polyaniline in the emeraldine salt form prepared using the counterion-induced processability technology disclosed in U.S. Pat. No. 5,232,631 and in Appl. Phys. Lett. 60, 2711 (1992) or other suitable techniques.
- the polyaniline film which serves as the electrode can be cast from solution with high uniformity at room temperature.
- the organic conducting electrodes in combination with polymer substrates and organic active layers allow these photosensors be fabricated in fully flexible form.
- Other conductive polymers can be used for the transparent or semitransparent electrode ( 11 in FIG. 1 or 13 in FIG.
- PEDT/PSS polyethylene dioxythiophene polystyrene sulfonate
- DBSA dodecylbenzene sulfonic acid
- a thin semitransparent layer of metals can also be used as the electrode 11 in FIG. 1 and 13 in FIG. 2.
- Typical thicknesses for this semitransparent metal electrode are in the range of 50-1000 ⁇ , with optical transmittance between 80% and 1%.
- a proper dielectric coating (often in the form of multilayer dielectric stacks) can enhance the transparency in the spectral range of interest [For examples, see S. M. Sze, Physics of Semiconductor Devices (John Wiley & Sons, New York, 1981) Chapter 13].
- a transparent electrode can also be made from metal/conducting polymer, conducting polymer/metal/conducting polymer or dielectric layer/metal/conducting polymer structures.
- the transmission properties of these composite electrodes are improved relative to that of a single metal layer of the same thickness.
- a metal layer with low optical transmittance can also be used as the electrode 11 for some applications in which spectral response at certain wavelengths is of interest.
- the photosensitivity can be enhanced by fabricating the device in a micro-cavity structure where the two metal electrodes 11 and 13 act also as optical mirrors. Light resonance between the two electrodes enhances the photosensitivity at certain wavelengths and results in selective spectral response, similar to that seen in optical microcavity (optical etalon) devices.
- the “back” electrode 13 in FIG. 1 (and 11 in FIG. 2) is typically made of a metal, such as Ca, Sm, Y, Mg, Al, In, Cu, Ag, Au and so on. Metal alloys can also be used as the electrode materials. These metal electrodes can be fabricated by, for example, thermal evaporation, electron beam evaporation, sputtering, chemical vapor deposition, melting process or other technologies.
- the thickness of the electrode 13 in FIG. 1 (and 11 in FIG. 2) is not critical and can be from hundreds of ⁇ ngstroms to hundreds of microns or thicker. The thickness can be controlled to achieve a desired surface conductivity.
- the transparent and semi-transparent materials described above can also be used as the “back” electrode 13 in FIG. 1 (and 11 in FIG. 2).
- the patterning of the row and column electrodes shown in FIG. 3 and FIG. 4 can be achieved by standard patterning technologies well-known in semiconductor industry such as shadow masking, photolithographing, silk-screen printing or stamp (microcontact) printing etc. These methods are well known to those knowledgeable of the art of display and image sensor technologies.
- a buffer layer comprising conducting polymers or blends containing them can be inserted in between the electrode 11 (or 13 ) and the photoactive layer.
- the conductivity of the buffer layer can be chosen from a broad range (between that of the pure conducting polymer and the photoactive material). Conductivity of the buffer layer is changed by processing conditions of the conducting polymer (counter-ion, solvent, concentration etc.) and the composition ratio of the blend. In certain situations the thickness of the buffer layer also affects the spectral response of the photosensor.
- multicolor detection or selected color detection are of interest. These can be achieved by properly selecting the material for the photoactive layer along with coupling the photosensor with a color filter coating.
- One type of application is a photosensor with selected spectral response, for example, from 500 to 600 nm.
- One effective approach is taking an organic photodiode with low energy cut-off at 600 nm (for example, a photodiode made with MEH-PPV), and placing a long-wavelength, low pass optical filter (with cut-off at 500 nm) in front.
- the spectral response of semiconducting oligomers and polymers can be controlled by modifying the side chain or main chain structures. For example, by varying the side chain of the PPV system, the optical gap can be tuned from 500 nm to 700 nm.
- An alternative approach to achieving bandpass selection is to place a bandpass optical filter in front of an organic photodiode with wider spectral response.
- full-color detection is frequently of interest. This can be achieved by splitting a sensor element (pixel) into three subpixels with response to red (600-700 nm), green (500-600 nm) and blue (400-500 nm) (R, G, B) spectral regions (as shown in FIG. 4) respectively, similar to that commonly used in liquid crystal display (LCD) color-display technologies.
- pixel sensor element
- red 600-700 nm
- green 500-600 nm
- blue 400-500 nm
- FIG. 4 A simple but effective approach to full-color image sensors is sketched in FIG. 4.
- the photodiode matrix is made of single sheet of active layer without patterning.
- the active areas are defined by the row and column electrodes.
- the spectral response of these organic photodiodes should cover the entire visible region (400-700 nm). Color selection is achieved by the color filter panel in front of the transparent electrodes.
- the photodetectors provided by the present invention can be adapted to respond to various types of ionized particles in addition to photons, themselves. This can be accomplished by incorporating in the photodetector structure a scintillating material adapted to emit photons in response to ionized particles.
- This material can be present in admixture with the active layer, it can be present as a separate layer or it can be present as part of the substrate or the transparent electrode.
- this scintillating material is a phosphor, present, for example as a phosphor layer.
- Examples of ionized particles which may be detected with devices of this structure are high energy photons, electrons, X-rays and ionized particles are characteristic of X-rays, beta particles and ionized particles are characteristic of gamma radiation.
- the invention of voltage-switchable organic photodiodes provides the foundation for fabrication of large size, low cost 2D image sensors based on x-y addressable passive diode matrices.
- This type of photodiode shows high photosensitivity (typically in the range of 30-300 mA/W), quantum efficiency (even over 100% electrons/photon at given reverse biases) and virtually zero response at a bias voltage close to the built-in potential.
- a row of pixels in a column-row matrix of such photodiodes can be selected by setting the selected row at reverse bias and the pixels on the other row biased at a voltage close to the built-in potential. In this way, crosstalk from pixels in different rows is eliminated.
- the image information at the pixels in the selected row can be read-out correctly in both the serial mode or the parallel mode.
- the information on the pixels in the other rows can be read-out in sequence or in selected fashion by setting the row of interest to reverse bias.
- the x-y addressable organic photodiode matrices provide a new type of 2D image sensor which can be made in large size, with low fabrication cost, onto substrates in desired shape or flexible, and hybridizable with other optical or electronic devices.
- Multi-color detection and full-color image sensing can be achieved by coupling the image matrix with a color filter panel or by fabricating the image sensor matrix directly onto a color filter panel.
- Voltage-switchable photodiodes were fabricated by evaporating a 5000 ⁇ calcium contact ( 13 ) on the front of a thin MEH-PPV film 12 which was spin-cast from solution onto a ITO/glass substrate 14 .
- the glass substrate had been previously partially coated with a contact layer 11 of indium-tin-oxide (ITO).
- ITO indium-tin-oxide
- the active area of each device was 0.1 cm 2 .
- the MEH-PPV film was cast from a 0.5% (11 mg/2 ml) xylene solution at room temperature. Details on the synthesis of MEH-PPV can be found in literature [F. Wudl, P. M. Allemand, G. Srdanov, Z. Ni, and D.
- the thickness of the active layer was adjusted by varying the concentration of the solution, by varying the spin speed of the spinner head and by applying multiple coating layers.
- FIG. 6 shows the magnitude of the photocurrent (absolute value) as a function of bias voltage under 20 mW/cm 2 illumination at 430 nm.
- the photocurrent at 1.5 V bias was ⁇ 3 ⁇ 10 ⁇ 8 A/cm 2 ,increasing to 9 ⁇ 10 ⁇ 4 A/cm 2 at ⁇ 10 V reverse bias corresponding to a photosensitivity of 45 mA/W and a quantum efficiency of 13% el/ph.
- the ratio of the photosensitivity between the two bias voltages was 3 ⁇ 10 4 , thus the photosensitivity at 1.5 V bias was practically zero in the read-out circuit. This degree of difference enabled an analog-to-digital (A/D) convertor of 8-12 bit resolution.
- A/D analog-to-digital
- the photoresponse increased nearly linearly with light intensity (I 0.921 ⁇ 1 ) over the entire range measured from nW/cm 2 to tens mW/cm 2 . No signature of saturation was observed at 20 mW/cm 2 (the highest light intensity in the measurement).
- Devices were also fabricated with other photoactive organic materials, including P3AT, POPT, PTV, PPV, BuEH-PPV, BUHP-PPV, C 60 , 6T, 6P, spiro-6P, Alq 3 , anthracene and phthalocyanine. Similar results to those shown in FIG. 6 were observed.
- This example demonstrates that high photosensitivity can be achieved with MEH-PPV organic photodiodes under reverse bias.
- the desired photosensitivity can be achieved at a given reverse bias.
- the photosensitivity can be switched off at a proper bias voltage which is dependent on the electrode materials selected.
- Table 1 air stable metals with work functions over 4 V can be used for the electrodes in organic photodiodes.
- This example also demostrates that the off-state voltage is determined by the work function of the electrode close to the interface area.
- This example also demonstrates the broad dynamic range of the polymer photodiodes, a dynamic range which is sufficient to enable image detection with multi-grey levels. TABLE 1 Off-state voltage in ITO/MEH-PPV/metal photodiodes Metal cathode Ca Sm Yb Al In Ag Cu V off (V) 1.5 1.5 1.5 1.1 0.9 0.7 0.4
- Example 1 Devices of Example 1 were fabricated onto flexible ITO/PET substrates. The thickness of the PET sheets used as substrates was 5-7 mils (125-175 ⁇ m). Similar device performance was observed.
- Example 1 Devices of Example 1 were fabricated on glass and PET substrates. In these devices, the ITO anode 11 was replaced with organic conducting coatings or with ITO overcoated with conducting organic films.
- PANI-CSA and PEDT/PSS were used as the organic electrode.
- the PANI-CSA layers were spin-cast from m-cresol solution [details about preparation of the PANI solution and PANI-CSA film have been disclosed in U.S. Pat. No. 5,232,631].
- the PEDT-PSS films were cast from an aqueous dispersion (1.3% W/W) which was supplied by Bayer [Bayer trial product, TP AI 4071], details about the synthesis can be found in the literature [G. Heywang and F. Jonas, Adv.
- the cast films were then baked at 50-85° C. for several hours in a vacuum oven or in a N 2 dry box. In the case of PEDT/PSS, the films were finally baked at a temperature over 100° C. for several minutes to complete the drying process.
- the thickness of the conducting polymer electrodes was controlled from a few hundred Angstroms to a few thousand Angstroms.
- the optical transmission spectra of the polymer anode electrodes are shown in FIG. 7, including data from PANI-CSA and PEDT-PSS. Also shown in FIG. 7 is the spectral response of the normal human eye, V( ⁇ ). The data indicate that these organic conducting electrodes can be used for photosensors for applications in visible spectral range. Moreover, the PEDT-PSS electrodes can also be used for ultraviolet (250-400 mn) and for near infrared. Thus, the polymer electrodes can be used in photosensors with full-color (white color or R, G, B three color) detection.
- the photosensitivities of the devices with organic anode electrodes or bilayer electrodes were similar to those shown in FIG. 6; i.e. tens of mA/W at reverse bias voltage in the ⁇ 5 to about ⁇ 10 V range.
- This example demonstrates that conducting polymer materials can be used as the transparent electrodes of the photodiodes and image sensors. These plastic electrode materials provide the opportunity to fabricate organic photosensors in flexible or foldable forms. This example also demonstrates that the polymer electrode can be inserted between a metal-oxide transparent electrode (such as ITO) and the active layer to modify the interfacial properties and the device performance.
- a metal-oxide transparent electrode such as ITO
- Example 1 Devices of Example 1 were repeated. A thin buffer layer was inserted between the ITO and the MEH-PPV layers to reduce the leakage current through pinhole imperfections in the active layer.
- the materials used for the buffer layer were PAZ, TPD (prepared via chemical vapor deposition) and PVK (cast from cyclohexanone solution).
- the thickness of the buffer layer was 100-500 ⁇ .
- the photoresponse of these devices was similar to that shown in FIG. 6. However, in these devices, the dark current (which is caused frequently from microshorts due to pinholes in the active layer) was reduced in magnitude. In these short-free devices, a photon flux as small as 1 nW/cm 2 was detected under direct current operation.
- the off-state voltage was 1.6 ⁇ 1.7 V in these devices, slightly higher than in the devices in Example 1.
- This example demonstrates that a buffer layer can be inserted between the active layer and the contact electrode(s) to reduce device shorts and to improve the device response to weak light.
- This buffer layer can be made of organic molecules via chemical vapor deposition or polymeric materials through wet casting processes.
- Example 1 Devices of Example 1 were repeated.
- the active material, MEH-PPV was blended with an anionic surfactant Li-CO436 in molar ratios of 0, 1, 5, 10 and 20%.
- the Li-CO436 was synthesized by a substitution reaction from Alipal CO436 (ammonium salt nonylphenoxy ether sulfate) supplied by Phone-Poulenc Co. [Y. Cao, U.S. patent application Ser. No. 08/888,316]. Al was used as the cathode. The photosensitivity was enhanced in the devices with blended Li-CO436.
- the photocurrent increased by a factor of 2 in a device made with MEH-PPV:Li-OC436 (10 wt %) compared with a similar device made without the Li-OC436.
- the off-state voltage shifted from 1.1 V in ITO/MEH-PPV/Al devices (see Example 1) to 1.5 V in the ITO/MEH-PPV:Li-OC436 (20%)/Al devices. Similar effects were also observed in devices having an ITO/MEH-PPV/Li-OC436/Al structure.
- the off-state voltage increases from 1.1 V to 1.6 V.
- Example 1 Devices of Example 1 were also fabricated with LiF, Li 2 O or BaO layers (1-30 nm) inserted between the MEH-PPV and the Al cathode. Similar enhancement of the short circuit current and the off-state voltage was observed.
- Example 1 Devices of Example 1 were also fabricated with a TiO 2 layer (1-30 nm) inserted between the MEH-PPV and the Al cathode, and with TiO 2 nanoparticles dispersed in the MEH-PPV film (forming a phase separated MEH-PPV:TiO 2 blend film. Similar results to those obtained with ITO/MEH-PPV/BaO/Al were observed.
- This example demonstrates that organic additives can be added to the active layer or inserted between the active player and the contact electrode to modify the device performance including photosensitivity and off-state voltage.
- This example also demonstrates that a layer of inorganic dielectric or semiconducting compounds can be inserted between the active layer and the contact electrode to modify device performance, including photosensitivity and off-state voltage.
- the inorganic dielectric or semiconducting compounds can also be made in nanoparticle form and blended with the organic photosensing materials.
- Voltage-switchable photodiodes were fabricated in the structure of ITO/MEH-PPV:PCBM/metal, similar to that shown in FIG. 1.
- the PCBM (a C 60 derivative) served as an acceptor in a donor-acceptor pair with the MEH-PPV acting as donor.
- the active area of these devices was ⁇ 0.1 cm 2 .
- the blend solution was prepared by mixing 0.8% MEH-PPV and 2% PCBM/xylene solutions with 2:1 weight ratio. The solution was clear, uniform, and was processable at room temperature. Solutions were stored in a N 2 box for over 1.5 years and no aggregation or phase separation were observed.
- the active layer was spin-cast from the solution at 1000-2000 rpm.
- Typical film thicknesses were in the range of 1000 ⁇ 2000 ⁇ . Ca, Al, Ag, Cu, and Au were used as the counter electrode 13 . In each case, the film was deposited by vacuum evaporation with thickness of 1000-5000 ⁇ . In another experiment, the concentration of the acceptor PCBM was varied from 0 to 1:1 molecular ratio. Higher on state photosensitivity and lower on-state operation voltage were observed in devices with higher concentrations.
- FIG. 8 shows the I-V characteristics of an ITO/MEH-PPV:PCBCR/Al device in the dark and under light illumination.
- the thickness of the blend film was ⁇ 2000 ⁇ .
- the dark current saturated at ⁇ 1 nA/cm 2 below 3 V and then increased superlinearly at high bias voltages (>E g /e). Zener tunneling can account for this effect.
- the photocurrent was measured.
- the photocurrent at 0.65 V was ⁇ 1 ⁇ 10 ⁇ 7 A/cm 2 , increasing to 5 ⁇ 10 4 A/cm 2 at ⁇ 10 V bias.
- the on-off ratio was ⁇ 500.
- Devices with thinner blend films showed improved photosensitivity and higher on-off ratio. Similar photosensitivity was also observed in devices fabricated with other metals or metal alloys as the counter electrodes. These included Ag, Cu, Ca, Sm, Pb, Mg, LiAl, MgAg, BaAl.
- This example demonstrates that the photosensitivity can be further improved by blending a donor polymer with a molecular acceptor such as C 60 , PCBM, PCBCR.
- High photosensitivity can be achieved at relatively low bias and low field ( ⁇ 10 5 V/cm).
- This example also demonstrates that the photosensitivity can be switched to nearly zero when bias the device at a voltage balancing the internal built-in potential ( ⁇ 0.65 V for Al cathode).
- the data in this example show that, due to its low dark current level, the polymer photodiode can be used to detect weak light down to intensity level of tens of nW/cm 2 .
- the polymer photodiodes have a dynamic range spanning more than six orders of magnitude, from nW/cm 2 to 100 mW/cm 2 .
- Example 6 Devices similar to those of Example 6 were fabricated with glass/ITO and PET/ITO substrates in 4.5 cm ⁇ 4 cm (18 cm 2 ) and in 3.8 cm ⁇ 6.4 cm (24.3 cm 2 ) using a fabrication process similar to that of Example 6. I-V characteristics similar to that shown in FIG. 8 were observed. The photodiodes made with flexible PET substrates were bent into circular shapes any without change in their photosensitivity.
- Devices were fabricated in the form of ITO/6P/C 60 /Al, ITO/6P/t-Bu-PBD/Al.
- the photoactive layer comprised two types of organic molecules in heterojunction form, made by thermal evaporation. Similar I-V characteristics to those shown in FIG. 8 were observed.
- Examples 8 and 9 demonstrate that the active layer of the voltage-switchable photodiodes can be organic molecules arranged in bilayer or multilayer structures, a blend of organic molecules, or a blend of conjugated polymers, in addition to a polymer/molecule blend as demonstrated in example 6.
- the data in these examples along with that in the Example 1 also demonstrate that, for a given cathode such as Ca, the off-state voltage varies with the electronic structure of the active material.
- This example demonstrates that the off-state of the photodiode can be varied by proper selection of the active material and the electrode materials. This voltage can be set to a voltage close to zero volts.
- a photodiode matrix fabricated with this type of photodiode can be driven by pulse trains with mono-polarity, thus simplifying the driving circuitry.
- the large on/off switching ratio and the large photocurrent/darkcurrent ratio permit the photodiodes to be used in the fabrication of x-y addressable passive matrices with high pixel density and with multiple-gray levels.
- Two-dimensional, photodiode matrices were fabricated with seven rows and 40 columns. Pixel size was 0.7 mm ⁇ 0.7 mm. The space between the row electrodes and the column electrodes was 1.27 mm (0.05′′). The total active area was ⁇ 2′′ ⁇ 0.35′′. Typical I-V characteristics from a pixel are shown in FIG. 10. White light from a fluorescent lamp on the ceiling of the lab was used as the illumination source with intensity of ⁇ tens of ⁇ W/cm 2 . This is much weaker than the light intensity used in document scanners.
- This example demonstrates that pixelated photodiode matrices can be fabricated without shorts and without crosstalk. This example also demonstrates that these devices can be used for applications with light intensities equal to or much less than a microwatt/cm 2 . Thus, polymer photodiode matrices are practical for image applications under relatively weak light conditions.
- FIG. 11 shows a instantaneous “snap-shot” of the voltage distribution in a 7 ⁇ 40 photodiode matrix.
- all the pixels were biased at +0.7 V except the pixels in column 1 .
- the pixels in column 1 were all biased at ⁇ 10 V so as to achieve high photosensitivity (tens-hundreds of mA/Watt).
- the information at each of the pixels in column 1 was read-out in both parallel (with N channel converting circuits and A/D converters) or serial (with N channel analog switches) sequences. Pixels in other columns were selected by switching the column bias from +0.7 V to ⁇ 10 V in sequence.
- a digital shift register was used for the column selection.
- the photosensor can be switched on and off between 0 V and a reverse bias voltage ( ⁇ 2 to ⁇ 10 V).
- a reverse bias voltage ⁇ 2 to ⁇ 10 V.
- This example demonstrates that the voltage-switchable photodiodes can be used as the pixel elements of a column-row matrix (as shown in FIG. 3).
- the photodiodes at each pixel can be addressed effectively from the column and row electrodes. Image information with multiple gray-levels can be read-out without distortion.
- Devices were also fabricated in the form of ITO/P3HT/P3HT:PCBM/A1. White light was used as the illumination source. Quantum efficiency of over 100% electrons/photon was observed. The highest value observed was ⁇ 1100% electrons/photon. A gain mechanism may play a role in these multilayer devices.
- This example demonstrates high photosensitivity organic photodetectors with response covering, simultaneously, the near UV and the entire visible spectra. This example also demonstrates that organic photodetectors in the metal/organic/metal sandwich structure can have quantum efficiency over 100% electrons/photon; i.e., possesses a gain mechanism.
- Voltage-switchable photodiodes were fabricated to achieve a response similar to the visual response of the human eye, V( ⁇ ).
- the devices were fabricated by coating a long-wavelength-pass filter onto the front panel of the glass substrates of devices, similar to those shown in Example 15.
- the coating material in this example was a layer of PPV which was converted from its precursor film at 230° C.
- the photoresponses of the devices with and without the filter are shown in FIG. 13A.
- the visual response of the human eye, V( ⁇ ) see FIG. 13B
- the transmittance of the PPV optical filter are shown for comparison.
- the photoresponse of the P3OT diode closely coincided with V( ⁇ ) for wavelengths longer than 560 nm, while the optical transmittance of the PPV filter followed V( ⁇ ) over a broad range between 450 nm and 550 nm.
- This example demonstrates a polymer photodetector with visual response essentially equivalent to V( ⁇ ), which is of great interest in optical engineering and biophysical/biomedical applications.
- FIG. 14 shows the spectral response of the UV detector operating at ⁇ 2V. The spectral response of the MEH-PPV:C 60 photodiode on ITO/glass substrate and the response of an UV-enhanced Si photodiode are plotted for comparison.
- the data show that the polymer UV detector was sensitive to UV radiation between 300-400 nm with photosensitivity of ⁇ 150 mA/W, comparable to that of UV-enhanced silicon photodiode.
- the data also show that the photoresponse of the MEH-PPV photodiode was suppressed (over 10 3 times) by the optical bandpass filter.
- Example 14 was repeated except that the active layer was a thin PTV layer.
- the spectral response of a PTV photodiode is shown in FIG. 15A, which covers the range from 300 to 700 nm; i.e., spanning the entire visible range. Selected color detection was achieved by inserting a bandpass filter or a long wavelength filter in front of the detectors.
- FIG. 15B shows the responses of a blue-color pixel, a green-color pixel and a red-color pixel made with a panel of color filters and an array of PTV photodiodes.
- the transmittance of the corresponding R, G, B color filters is shown in FIG. 15C.
- Red, green and blue (R, G, B) color detection were achieved following the approach shown in FIG. 5.
- the materials used for the active layers were PPV with a long wavelength cut-off at 500 nm; poly(dihexyloxy phenylene vinylene), “PDHPV”, with a long wavelength cut-off at 600 nm; and PTV with long wavelength cut-off at 700 nm.
- Films were cast from solutions in their precursor forms with thickness between 1000 ⁇ -3000 ⁇ . Conversion to the conjugated forms was carried out at temperatures between 150-230° C. The conjugated films formed in this way were insoluble to organic solvents.
- Red and green selective color detection were achieved by differentiation of the signals from these photodiodes (this operation can be done in the read-out circuit).
- the differential responses of these photodiodes are shown in FIG. 16B.
- Red color detection (with response between 600-700 nm) was achieved by subtracting the signal from the PTV photodiode from the signal from the PDHPV photodiode.
- Green color detection (with response between 500-600 nm) was achieved by subtraction of the PDHPV signal from the PPV signal. The blue color detection was obtained by PPV photodiode directly.
- Voltage-switchable photodiodes were fabricated with the conjugated polymer poly(p-phenyl vinylene), PPV as photoactive material.
- the PPV films were spin-cast onto ITO substrates from a nonconjugated precursor solution and then converted to conjugated form by heating at 200-230° C. for 3 hours. Al was used as the back electrode.
- the active area was ⁇ 0.15 cm 2 .
- the I-V characteristics of this photodiode in the dark and under illumination are shown in FIG. 17.
- the photocurrent/darkcurrent ratio is in the range of 10 4 for white light illumination of a few mW/cm 2 .
- Relatively low dark current was observed in forward bias as compared to that observed in photodiodes of, for example, in Example 1. This allows photodetection in both forward bias and reverse bias as shown in FIG. 17.
- the photosensitivity can be switched on and off by varying the external biasing voltage. For example, under white (or UV) light illumination, the photocurrent at +5V or ⁇ 5V is 2000 times higher than that at +0.95V (or 0.3V).
- This example demonstrates that the photodiode can be switched on by applying a forward bias (beyond the vicinity of the voltage corresponding the off state) or a reverse bias.
- Photodiodes operable in both switch polarities are useful in certain circuit designs and applications.
- Voltage-switchable photodetectors were fabricated which had a heterojunction structure as their active layers, they had an ITO/donor layer/acceptor layer/metal structure.
- the materials used for the donor layer were MEH-PPV and PPV.
- the material used for the acceptor layer were C 60 , laid down by physical vapor deposition and PCBM and PCBCR laid down by drop casting or spin casting.
- a data set for a MEH-PPV/C 60 photodiode is shown in FIG. 18.
- Voltage-switchable photosensors was fabricated in the configuration shown in FIG. 1. Glass with patterned ITO was used as the substrate. The size of each test pixel was ⁇ 0.1 cm 2 .
- the sensing material used was poly(3-hexyl thiophene), P3HT, which was spin cast at room temperature from a 2.5 wt % solution in toluene. Similar to the spectral response of P3OT (see Example 10), the photoresponse of P3HT sensor covers the entire visible and near UV spectral region such that red, green and blue full-color recognition can be achieved by color filtering techniques.
- FIG. 19 shows the photo- and dark currents from a P3HT device with 3150 ⁇ film thickness.
- the data were taken with white light illumination of 8 mW/cm 2 (between 400 nm and 700 nm) and with monochromatic light (600 nm at 1.1 mW/cm 2 ).
- the reverse current saturates at low field region and then increases with the biasing voltage, to ⁇ 2 ⁇ 10 ⁇ 5 mA/cm 2 at ⁇ 25 V bias.
- the forward current increases exponentially under forward bias (for voltages >1 V), reaching ⁇ 1 mA/cm 2 at 3 V bias.
- the exponential forward current covers more than 5 orders of magnitude in the voltage range from 1-2 V.
- the rectification ratio at 2 V is over 10 4 . Strong photosensitivity was observed in reverse bias.
- the photocurrent at ⁇ 25 V reaches 5.33 mA/cm 2 under 8 mW/cm 2 , white light illumination. This number corresponds to a photoresponsivity of in excess of 0.5 A/W, corresponding to a quantum efficiency larger than 100% electrons/photon.
- a high I ph (V on )/I ph (V off ) switching ratio was also achieved in this devices: under 8 mW/cm 2 , I ph ( ⁇ 25V)/I ph (0.5)is ⁇ 4 ⁇ 10 7 .
- This switching ratio is equal to or even better than the switching ratio of TFT-based photosensors made with inorganic semiconductors (10 4 -10 7 ). These organic photodiodes also exhibit a high I ph (V)/I dark (V) ratio.
- the I ph /I dark at ⁇ 25 V is ⁇ 4 ⁇ 10 5 for 8 mW/cm 2 white light illumination, which implies that more than 18 bits (2.6 ⁇ 10 5 ) gray levels can be resolved for image applications.
- the high switching ratio implies that for an x-y addressable 2D photodiode matrix of 400 ⁇ 390 pixels (refer to FIG. 3 of the 2D patent), more than 256 gray levels can be resolved.
- Adopting quad-matrix design (four sub-matrices arranged in each quadrants), more than 1000 ⁇ 625 pixels are possible with the same resolution. This pixel density is even better than the SVGA standard.
- the drive circuit for these photodiode matrices is simplified; digital shift registers and BCD digital decoders can be used.
- This example demonstrates an organic photosensor with high switching ratio and high I ph /I dark ratio.
- the photosensitivity of such photosensors covers the entire visible spectral range.
- These sensors are especially suitable for constructing linear photodiode arrays and 2D photodiode matrices for high quality image sensing applications.
- Linear photodiode arrays were fabricated with 102 sensing elements, each made with P3OT as the semiconducting polymer. Two typical structures of the photodiode arrays are shown in FIG. 20A and FIG. 20B. The pixel size was ⁇ 0.635 mm ⁇ 0.635 mm. The length of the total sensing area was ⁇ 2.5′′, longer than any linear photodiode array commercially available.
- a full-color linear scanner was constructed with a sensing circuit shown in FIG. 21, no analog switching elements (such as field effect transistors) were used in this driver. The read out circuit was digitized into 8 bit with 256 gray levels.
- Red, green and blue color filters were mounted on a panel and was switched in front of the linear diode array when collecting the corresponding images.
- the linear photodiode array was mounted on a computer controlled translation stage for the image scanning. A full-color image taken with this scanner is shown in FIG. 22D. It was recovered by a superposition of the red, green and blue color images (FIGS. 22 ( a, b, c )) taken separately.
- the image quality was similar to that achieved with a commercial color scanner in the same pixel format (40 dpi) with so-called “multi-million ( 256 3 ) colors” format.
- Linear photodiode arrays were also fabricated in 40 dpi and 50 dpi forms with total pixels of 200 and 240. The total sensing length is close to 5′′. The arrays were used for image sensing experiments. Large size (5′′ ⁇ 11′′), high quality (8-10 bit), full-color image sensing was demonstrated.
- Example 22 The linear photodiode arrays demonstrated in Example 22 were also used for visible-blind UV sensing.
- a visible blocking, UV pass filter was placed in front of the array.
- the UV image generated with UV ink was projected onto the sensor.
- the UV image was read out with the organic photodiode array.
- Linear photodiode arrays were fabricated in the same configuration as that of Example 22 (1 ⁇ 102 pixels, 40 pixels/in). One of the sensor arrays was used as an optical beam analyzer to test the optical field distribution a laser beam. The intensity distribution of the testing optical field is shown in FIG. 23. This example demonstrates that the polymer photodiode array can be used to detect spatial distribution of an optical beam. This function is of broad applications in industrial automation.
- FIG. 24 Another 1 ⁇ 102 linear photodiode array was fabricated on PET substrate (7 mil in thickness).
- the flexible sensor array was arranged in a semicircular shape.
- a point light source from a green light emitting diode was placed at the center of the circle, and the angular distribution of the light intensity was tested with the curved sensor array. The result is shown in FIG. 24.
- polymer linear photodiode arrays can be fabricated onto flexible substrates or on curved substrates to fit into an optical apparatus or to probe the spatial distribution of an optical field.
- the fabrication process and the thin film architecture of the polymer photodiode arrays also allow them to be integrated with electronic drivers on a silicon wafer or integrated with an adapted optical component.
- a P3OT photodiode array was used as the detector of an UV-visible spectrometer for transmission measurement.
- the setup is shown in FIG. 25.
- Voltage-switchable photosensors were fabricated in a metal(1)/P3HT/metal(2) sandwich structure.
- metal(1) was Au and metal(2) was Al.
- the thickness of the Au layer was varied from 20 nm to 80 nm and the optical transmission of the Au layer was varied from 50% to ⁇ 1%.
- the optical reflection of the Au layer varies correspondingly.
- the thickness of the Al layer was more than 100 nm, so that its reflectance was almost 100%.
- Such a metal/organic layer/metal structure forms an optical microcavity (optical etalon) device in the spectral region where the optical absorption of the organic layer is relatively low.
- Such a microcavity structure possesses optical resonance at selected wavelengths.
- the center wavelength and the bandwidth of the sensing profile can be adjusted by changing the reflection of the metal electrode, by the absorption coefficient, the dielectric constant and the thickness of the organic layer.
- FIG. 27 shows the spectral response of such device.
- Microcavity devices were also made in the “reverse” structure similar to that shown in FIG. 2; i.e., with light incident onto the free surface electrode ( 13 ).
- the devices were made in both configurations: glass/Au(100 nm)/MEH-PPV/Ag(50 nm) and glass/Ag(100 nm)/MEH-PPV/Au(50 nm).
- Au acts as the anode
- Ag as the cathode.
- Selective spectral response was observed in both structures.
- Wavelength selective photosensors were also fabricated with substrates containing an optical stack (sometimes called DBR, Defractive Bragg Reflector). The transmission of the DBR was ⁇ 2%.
- the photosensors were fabricated as follows: glass/DBR/ITO/MEH-PPV:PCBM/Al. Wavelength selective spectral response was observed with ⁇ 2 nm bandwidth.
- This example also demonstrates that the organic photosensors can be constructed with wavelength selectivity of narrow bandwidth. Building such a photodiode array or 2D matrix in which each pixel has a different sensing profile forms a flat-panel spectrometer. These kinds of devices have great potential for image sensing, spectrographic, biophysical and biomedical applications.
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Electromagnetism (AREA)
- Chemical & Material Sciences (AREA)
- Power Engineering (AREA)
- Nanotechnology (AREA)
- General Physics & Mathematics (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Computer Hardware Design (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- Mathematical Physics (AREA)
- Theoretical Computer Science (AREA)
- Crystallography & Structural Chemistry (AREA)
- Materials Engineering (AREA)
- Solid State Image Pick-Up Elements (AREA)
- Light Receiving Elements (AREA)
- Transforming Light Signals Into Electric Signals (AREA)
- Color Television Image Signal Generators (AREA)
Abstract
Organic photodetectors with switchable photosensitivity are achieved using organic photoactive layers in electrode/organic/electrode structures. The photosensitivity can be switched on and off by the biasing voltage across the detectors. The photocurrent can be probed with a read-out circuit in the loop. These photodetectors can be arranged in linear arrays or in two-dimensional matrices that function as high performance, linear or two-dimensional image sensors. These image sensors can achieve fill color or selected color detection capability.
Description
- This application claims the benefit of U.S. Provisional Application No. 60/073,346, filed Feb. 2, 1998, which application is incorporated herein by reference in its entirety.
- [0002] This invention was made partially with Government support under Grant No. SBIR Ph I DMI 9660975 awarded by the National Science Foundation. Accordingly, the Government has certain rights to this invention.
- 1. Field of the Invention
- The present invention relates to organic, polymer-based photodiodes and to their use in one and two dimensional image sensors. In more preferred embodiments, it concerns organic polymer-based photodiodes which are voltage switchable and which may be arrayed as image sensors in the form of a column-row (x-y) passively addressable matrix, where the x-y addressable organic image sensors (image arrays) have fall-color or selected-color detection capability, or as linear photodiode arrays.
- 2. State of the Art
- The development of image array photodetectors has a relatively long history in the solid state device industry. Early approaches to imaging technology included devices based on thermal effects in solid state materials. These were followed by high sensitivity image arrays and matrices based on photodiodes and charge-coupling devices (“CCDs”) made with inorganic semiconductors. These arrays can be simple linear (or “one dimensional”) arrays which scan an image or they can be two dimensional, like the image.
- Photodiodes made with inorganic semiconductors, such as silicon, represent a class of high quantum yield, photosensitive devices. They have been used broadly in visible light detection applications in the past decades. However, they characteristically present a flat current-voltage response, which makes it difficult to use them in fabricating high pixel density, x-y matrix-addressable passive image sensors. An “x-y” matrix is a two dimensional array with a first set of electrodes perpendicular to a second set of electrodes. When passive devices such as resistors, diodes or liquid crystal cells are used as the pixel elements at the intersection points, the matrix is often called a “passive” matrix in contrast to an “active” matrix in which active devices, such as transistors, are used to control the turn-on for each pixel.
- To effectively address an individual pixel from the column and row electrodes in a two dimensional passive matrix, the pixel elements must exhibit strongly nonlinear current-voltage (“I-V”) characteristics or an I-V dependence with a threshold voltage. This requirement provides the foundation for using light-emitting diodes or liquid crystal cells to construct passive x-y addressable displays. However, since the photoresponse of inorganic photodiodes is voltage-independent in reverse bias, photodiodes made with inorganic semiconductor crystals are not practical for use in high pixel density, passive image sensors—there is too much cross-talk between pixels. To avoid cross-talk, existing two dimensional photodiode arrays made with inorganic photodiodes must be fabricated with each pixel wired up individually, a laborious and costly procedure. In the case of such individual connections, the number of input/output leads is proportional to the number of the pixels. The number of pixels in commercial two dimensional photodiode arrays is therefore limited to ≦16×16=256 due to the difficulties in manufacturing and in making inter-board connections. Representative commercial photodiode arrays include the Siemens KOM2108 5×5 photodiode array, and the Hamamatsu S3805 16×16 Si photodiode array.
- The development of charge-coupled devices (“CCDs”) provided an additional approach toward high pixel density, two-dimensional image sensors. CCD arrays are integrated devices. They are different than x-y addressable matrix arrays. The operating principle of CCDs involves serial transfer of charges from pixel to pixel. These interpixel transfers occur repeatedly and result in the charge migrating, eventually, to the edge of the array for read-out. These devices employ super-large integrating circuit (“SLIC”) technology and require an extremely high level of perfection during their fabrication. This makes CCD arrays costly (˜$103-104 for a CCD of 0.75″ −1″ size) and limits commercial CCD products to sub-inch dimensions.
- The thin film transistor (“TFT”) technology on glass or quartz substrates, which was developed originally for the needs of liquid crystal displays, can provide active-matrix substrates for fabricating large size, x-y addressable image sensors. A large size, full color image sensor made with amorphous silicon (a-Si) p-i-n photocells on a-Si TFT panels was demonstrated recently [R. A. Street, J. Wu, R. Weisfield, S. E. Nelson and P. Nylen, Spring Meeting of Materials Research Society, San Francisco, Apr. 17-21 (1995); J. Yorkston et al., Mat. Res. Soc. Sym. Proc. 116, 258 (1992); R. A. Street, Bulletin of Materials Research Society 11(17), 20 (1992); L. E. Antonuk and R. A. Street, U.S. Pat. No. 5,262,649 (1993); R. A. Street, U.S. Pat. No 5,164,809 (1992)]. Independently, a parallel effort on small size, active-pixel photosensors based on CMOS technology on silicon wafers has been re-activated following developments in the CMOS technology which provide submicron resolution [For a review of recent progress, see: Eric J. Lemer, Laser Focus World 32(12) 54, 1996]. This CMOS technology allows the photocells to be integrated with the driver and the timing circuits so that a mono-chip image camera can be realized.
- CCDs, a-Si TFTs, and active-pixel CMOS image sensors represent the existing/emerging technologies for solid state image sensors. However, because of the costly processes involved in fabrication of these sophisticated devices, their applications are severely limited. Furthermore, the use of SLIC technologies in the fabrication processes limits the CCDs and the active-pixel CMOS sensors to sub-inch device dimensions.
- Photodiodes made with organic semiconductors represent a novel class of photosensors with promising process advantages. Although there were early reports, in the 1980s, of fabricating photodiodes with organic molecules and conjugated polymers, relatively small photoresponse was observed [for an review of early work on organic photodiodes, see: G. A. Chamberlain, Solar Cells 8, 47 (1983)]. In the 1990s, there has been progress using conjugated polymers as the active materials; see for example the following reports on the photoresponse in poly(phenylene vinylene), PPV, and its derivatives,: S. Karg, W. Riess, V. Dyakonov, M. Schwoerer, Synth. Metals 54, 427 (1993); H. Antoniadis, B. R. Hsieh, M. A. Abkowitz, S. A. Jenekhe, M. Stolka, Synth. Metals 64, 265 (1994); G. Yu, C. Zhang, A. J. Heeger, Appl. Phys. Lett. 64,1540 (1994); R. N. Marks, J. J. M. Halls, D. D. D. C. Bradley, R. H. Frield, A. B. Holmes, J. Phys.: Condens.
Matter 6,1379 (1994); R. H. Friend, A. B. Homes, D. D. C. Bradley, R. N. Marks, U.S. Pat. No. 5,523,555 (1996)]. - The photosensitivity in organic semiconductors can be enhanced by excited-state charge transfer; for example, by sensitizing the semiconducting polymer with acceptors such as C60 or its derivatives [N. S. Saricifici and A. J. Heeger, U.S. Pat. No. 5,331,183 (Jul. 19, 1994); N. S. Saricifici and A. J. Heeger, U.S. Pat. No. 5,454,880 (Oct. 3, 1995); N. S. Sariciftci, L. Smilowitz, A. J. Heeger and F. Wudl, Science 258, 1474 (1992); L. Smilowitz, N. S. Sariciftci, R. Wu, C. Gettinger, A. J. Heeger and F. Wudl, Phys. Rev. B 47, 13835 (1993); N. S. Saricifici and A. J. Heeger, Intern. J. Mod. Phys.
B 8, 237 (1994)]. Photoinduced charge transfer prevents early time recombination and stabilizes the charge separation, thereby enhancing the carrier quantum yield for subsequent collection [B. Kraabel, C. H. Lee, D. McBranch, D. Moses, N. S. Sariciftci and A. J. Heeger, Chem. Phys. Lett. 213, 389 (1993); B. Kraabel, D. McBranch, N. S. Sariciftci, D. Moses and A. J. Heeger,Phys. Rev. B 50,18543 (1994); C. H. Lee, G. Yu, D. Moses, K. Pakbaz, C. Zhang, N. S. Sariciftci, A. J. Heeger and F. Wudl, Phys. Rev. B. 48, 15425 (1993)]. By using charge transfer blends as the photosensitive materials in photodiodes, external photosensitivity of 0.2-0.3 A/Watt and external quantum yields of 50-80% el/ph have been achieved at 430 nm at low reverse bias voltages [G. Yu, J. Gao, J. C. Hummelen, F. Wudl and A. J. Heeger, Science 270, 1789 (1995); G. Yu and A. J. Heeger, J. Appl. Phys. 78, 4510 (1995); J. J. M. Halls, C. A. Walsh, N. C. Greenham, E. A. Marseglia, R. H. Frield, S. C. Moratti and A. B. Holmes, Nature 376, 498 (1995)]. At the same wavelength, the photosensitivity of the UV-enhanced silicon photodiodes is ˜0.2 A/Watt, independent of bias voltage [S. M. Sze, Physics of Semiconductor Devices (Wiley, New York, 1981) Part 5]. Thus, the photosensitivity of thin film photodiodes made with polymer charge transfer blends is comparable to that of photodiodes made with inorganic semiconducting crystals. In addition to their high photosensitivity, these organic photodiodes show large dynamic range; relatively flat photosensitivity has been reported from 100 mW/cm2 down to nW/cm2; i.e., over eight orders of magnitude [G. Yu, H. Pakbaz and A. J. Heeger, Appl. Phys. Lett. 64, 3422 (1994); G. Yu, J. Gao, J. C. Hummelen, F. Wudl and A. J. Heeger, Science 270, 1789 (1995); G. Yu and A. J. Heeger, J. Appl. Phys. 78, 4510 (1995)]. The polymer photodetectors can be operated at room temperature, and the photosensitivity is relatively insensitive to the operating temperature, dropping by only a factor of 2 from room temperature to 80 K [G. Yu, K. Pakbaz and A. J. Heeger, Appl. Phys. Lett. 64, 3422 (1994)]. - As is the case for polymer light-emitting devices [G. Gustafsson, Y. Cao, G. M. Treacy, F. Klavetter, N. Colaneri, and A. J. Heeger, Nature 357, 477 (1992); A. J. Heeger and J. Long, Optics & Photonics News, Aug. 1996, p.24], high sensitivity polymer photodetectors can be fabricated in large areas by processing from solution at room temperature. They can be made in unusual shapes (e.g. on a hemisphere to couple with an optical component or an optical system), or they can be made in flexible or foldable forms. The processing advantages also enable one to fabricate the photosensors directly onto optical fibers. Similarly, polymer photodiodes can be hybridized with optical devices or electronic devices, such as an integrated circuits on a silicon wafer. These unique features make polymer photodiodes special for many novel applications.
- Recent progress in our group has demonstrated that the photosensitivity in organic photodiodes can be enhanced by applying a reverse bias. It was further found that the photosensitivity increases with reverse bias voltage, with the increase being independent of incident light intensity [G. Yu, C. Zhang and A. J. Heeger, Appl. Phys. Lett. 64, 1540 (1994); A. J. Heeger and G. Yu, U.S. Pat. No. 5,504,323 (1996)]. This work showed a photosensitivity of ˜90 mA/Watt in poly(2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene) (“MEH-PPV”)-based thin film devices, such as ITO/MEH-PPV/Ca thin film devices, at 10 V reverse bias (430 nm), corresponding to a quantum efficiency of >20% el/ph. In photodiodes fabricated with poly(3-octylthiophene), photosensitivity over 0.3 A/Watt was observed over most of visible spectral range at −15 V bias [G. Yu, H. Pakbaz and A. J. Heeger, Appl. Phys. Lett. 64, 3422 (1994)].
- We have now found that this variable photosensitivity enables on-off voltage-switchable photosensors. At a reverse bias, typically in the range of 2-15 V, the photodiode can be switched on with photosensitivity of 30-300 mA/W. The photosensitivity at a voltage close to the internal (built-in) potential is several orders of magnitude lower, equivalent to zero at the output of a digital read-out circuit. This near zero state can thus be defined as the off state of the photodiode.
- These voltage-switchable, organic photodiodes can serve as individual pixels in passive diode arrays. These arrays can be in the form of x-y addressable arrays with anodes connected via row (column) electrodes and cathodes connected via column (row) electrodes. Every pixel can be selected, and the information (intensity of the incident light) at each pixel can be read out without crosstalk. Alternatively, the voltage-switchable, organic photodiodes can be arrayed in a linear manner.
- These arrays can utilize the processing advantages associated with the fabrication of organic diode structures from soluble, semiconducting, conjugated polymers (and/or their precursor polymers). Layers of these materials can be cast from solution to enable the fabrication of large active areas, onto substrates with desired shapes. This also enables active areas to be in flexible form. These photoactive materials can be patterned onto an optically uniform substrate by means of photolithography, microcontact printing, shadow masking and the like. In a preferred embodiment for the visible region of the spectrum, the substrate is opaque for λ<400 nm so that the pixels are insensitive to UV radiation.
- The photoactive layer employed in these switchable photodiodes is made up of organic materials. These take numerous forms. They can be conjugated semiconducting polymers or polymer blends. For donor-acceptor blends with polymeric donors, the acceptor can be a polymer, macromolecule, oligomer or small molecule (monomers). Alternatively, molecular donor/polymeric acceptor systems also work well. The higher molecular weight component in many cases provides mechanical strength and prevents phase changes. The donor-acceptor blends can also be made with small molecule donors and acceptors that are well known in the art. Examples of the molecular and oligomeric donors include anthracene and its derivatives, pinacyanol and its derivatives thiophene oligomers (such as sexithiophene.6T, and octylthiophene, 8T) and their derivatives and the like, phenyl oligomers (such as sexiphenyl or octylphenyl) and the like. Examples of molecular acceptors include fullerenes (such as C60 and their functional derivatives), Alq3-type organometallic molecules and the like. In addition, one can employ multiple layers of organic semiconducting materials in donor/acceptor heterojunction or quantum-well configurations.
- The organic image sensors enabled by this invention can have mono-color or multi-color detection capability. In these image sensors color (optical wavelength) selection can be achieved by combining a suitable color filter panel with the organic image sensors and image sensor arrays already described. If desired, the color filter panel can serve as a substrate upon which the image sensor is carried. The detection wavelength of the organic image sensors can also be selected by using resonant cavity device structures as demonstrated in the examples of the invention. The organic image sensor arrays with the ability to select specific wavelengths can be used for spectrographic applications (such as flat-panel spectrometers).
- In addition, embodiments of the present invention provide organic image sensors with full-color detection capability. In these organic image sensors, a filter panel is made up of red, green and blue color filters which are patterned in a format corresponding to the format of a photodiode array. The panel of patterned filters and the patterned photodiode array are coupled (and coordinated) such that a colored image sensor is formed. The patterned color filter panel can be used directly as the substrate of the image sensor.
- Full-color detectivity, is also achieved when red, green and blue colors are detected by three of these photodiodes with spectral response cut-off at 500 nm, 600 nm and 700 nm, respectively. Differentiation operations in the read-out circuit extract the red (600-700 nm), green (500-600 nm) and blue (400-500 nm) signals.
- This invention will be further described with reference being made to the drawings in which:
- FIG. 1 is a cross-sectional schematic view of a voltage-switchable photodiode of this
invention 10 assembled into a circuit. The photocurrent can be read out by a current meter or a read-out device inserted in the loop; - FIG. 2 is a cross-sectional schematic view of a voltage-
switchable photodiode 20 in reversed configuration, in which the reversed configuration refers the structure with the transparent electrode contacted with the free surface of the active layer; - FIG. 3 is an exploded schematic view of a
2D image sensor 30 made of an x-y addressable, passive matrix of voltage-switchable photodiodes; - FIG. 4 is an exploded schematic view of a full-
color image sensor 40 made with an x-y addressable photodiode matrix coupled to a color filter panel; - FIG. 5 is an exploded schematic view of a full-
color image sensor 50 made with an x-y addressable photodiode matrix of which each full-color pixel is made of three photosensitive materials having differing long-wavelength cut-offs such as at 700 nm, 600 nm and 500 nm; - FIG. 6 is a graph of the photocurrent as a function of bias voltage in a ITO/MEH-PPV/Ca device;
- FIG. 7 is a graph of the transmission characteristics of PANI-CSA and PEDT-PSSA conducting polymer electrodes; also shown is the visual response, V(λ), of human eye.
- FIG. 8 is a graph of the photocurrent (circles) and the dark current (solid line) of a ITO/MEH-PPV:PCBM/Al photodiode. The photocurrent was taken under white light of intensity ˜10 mW/cm2.
- FIG. 9 is a graph of the current-voltage characteristics of an ITO/P3OT/Au photodiode in the dark (circles), and illuminated under ˜10 mW/cm at 633 nm (squares);
- FIG. 10 is a graph of the current-voltage characteristics measured between a row electrode and a column electrode from a 7×40 photodiode matrix in the dark (lines) and under room light illumination (circles);
- FIG. 11 is a schematic representation of the driving scheme for a 7×40 photodiode matrix. It will be described in terms of ITO/MEH-PPV:PCBM/Ag switchable photodiodes;
- FIG. 12 is a graph of the photoresponse of a voltage-switchable photodiode made with P3OT;
- FIG. 13A is a graph of the photoresponse of voltage-switchable photodiodes with spectral response simulating that of human eye, V(λ);
- FIG. 13B is a graph of the transmittance of the long-wavelength-pass filter and the visual response, V(λ) corresponding to FIG. 13A;
- FIG. 14 is a graph of the spectral response of a solar blind UV detector operating at −2V. The photoresponse of the MEH-PPV:C60 photodiode on ITO/glass substrate and the photoresponse of an UV-enhanced Si photodiode are plotted for comparison;
- FIG. 15A is a graph of the response of a PTV photodiode;
- FIG. 15B is a graph of the photoresponse of R, G, B photosensors made of PTV photodiodes coupled with a color-filter panel;
- FIG. 15C is a graph of the transmittance of the color filters used in the generation of the data graphed in FIGS. 15A and 15B;
- FIG. 16A is a graph of normalized spectral response of photodiodes made with PPV (open squares), PDHPV (open circles), and PTV (solid circles);
- FIG. 16B is a graph of red, green and blue color detection derived from the diode responses in FIG. 16A;
- FIG. 17 is a graph showing I-V response of a photodiode made with PPV in the dark and under illumination;
- FIG. 18 is a graph showing I-V response of a photodiode with a donor/acceptor heterojunction structure in the dark and under illumination;
- FIG. 19 is a graph of the dark (solid circles) and photocurrents (circles) of a P3HT photodiode under 8 mW/cm2 broad band white light (400-700 nm);
- FIGS. 20A and 20B are cross-sectional schematic views of linear photodiode arrays made with organic semiconductors;
- FIG. 21 is a sketch of the circuit used to drive the organic photodiode array;
- FIGS.22A-D show images achieved by a P30T linear photodiode array of 100 pixels over a 2.5 inch length. FIG. 22A is a red color image; FIG. 22B is a green color image; FIG. 22C is a blue color image; and FIG. 22D is a full-color image recovered by superposing the red, green and blue color images of FIGS. 22A-C;
- FIG. 23 is a graph of an optical beam analyzer made with a 1×102 polymer photodiode array;
- FIG. 24 is a graph of the angular distribution of the light emission from a GaP LED measured with a flexible linear photodiode array;
- FIG. 25 is a schematic view of a spectrographer made of P30T photodiode array;
- FIG. 26 is a graph of the transmission spectra of a PPV film measured with the spectrographer of FIG. 25.
- FIG. 27 is a graph of the spectral response of an organic photosensor in microcavity (optic etalon) structure.
- This invention provides high sensitivity photodiodes with voltage-switchable photosensitivity; the photosensitivity can be switched on and off by the application of selected voltages, thereby reducing cross-talk between pixels in an array of such voltage-switchable photodiodes to acceptable levels. These switchable photosensors enable the fabrication of either one- or two-dimensional (2D), passive image sensors with column-row (x-y) addressability. The voltage-switchable photodetector is constructed in a metal-semiconductor-metal (M-S-M) thin film structure in which an organic film such as a film of semiconducting polymer or a polymer blend is used as the photoactive material. Selected-color or multi-color detection in the visible and near UV can be achieved by coupling the image sensor to an optical filter(s). Fabrication processes for red, green and blue (RGB) and full-color image sensors are described by coupling the x-y addressable polymer diode matrix or linear array with a RGB color filter panel, or by fabricating photodiodes with cut-off of the photoresponse at 500 nm, 600 nm and 700 nm, respectively, onto optically uniform substrates, or by fabricating the photodiodes in microcavity structures with defined spectral responses in the red, green and blue regions.
- Voltage-switchable photodiodes make possible 2D image sensors. Using such photodiodes as the sensing elements in a column-row matrix, a 2D x-y addressable, passive image sensor can be constructed which operates without crosstalk. Because of the strong voltage dependence of the photosensitivity, a column of pixels in the 2D photodiode matrix can be selected and turned on with proper voltage bias, leaving the rest of the pixels on other rows insensitive to the incident light. With this type of operation, the physical M row, N column 2D matrix is reduced to N isolated linear diode arrays each with M elements; said isolated linear diode arrays are free from the crosstalk which originates from finite resistance between devices on different columns. With such 2D, passive photodiode arrays, an image can be read out with a pulse train scanning through each column of the matrix. Since the number of contact electrodes are reduced to N+M in the x-y addressable matrix, compared to N×M in the case of individual connection, large size, high pixel density, 2D image arrays become practical (comparable to the high pixel density display arrays made with LCD technology). For example, for a 1000 by 1000 pixel array, the present invention reduces the number or required electrodes by 500 times. The polymer image sensor matrix thus provides a unique approach to fabricating large size, low cost, high pixel density, 2D image sensing arrays with a room temperature manufacturing process.
- In addition to being used as the sensing elements in x-y addressable, 2D passive photodiode matrices, these voltage-switchable organic photosensors can also be used to construct linear photodiode arrays. As shown in examples disclosed in this invention, the ratio of Iph(Von)/Iph(Voff) can be more than 3×107 under photoexcitation of a few mW/cm2. The large Iph(Von)/Idark(Von) ratio (>1.3×105) allows the collection of image data with gray scale resolution of more than 12 bits (12 bit has 4096 gray levels). Linear photodiode arrays made with these materials can be used for high image quality (over 18 bits), full-page color digital image scanners. Contrary to active image sensors, no analog switches are needed to drive these arrays. A digital shift register or a BCD decoder can be used for pixel selection.
- The device structure of the linear photodiode array is shown in FIG. 19. Transparent glass or PET films can be used as the substrates. Opaque materials such as silicon wafers can also be used as the substrate material. In this case, the light is incident onto the free surface side as shown in FIG. 19B. When organic PET films are used as substrates, the linear diode array can be made in flexible form. Optical devices with curved surface can also be used as the substrate for these diode arrays; i.e., the linear diode array can be coupled to and integrated with other optical devices in a desired optical arrangement and with a desired optical wavefront.
- Linear photodiode arrays can be made in the configurations similar to that shown in FIG. 3 with one row and n columns or with one column and n rows. The cross sectional views of two typical device structures are shown in FIG. 19. The substrates can be transparent or opaque. In a preferred configuration (FIG. 19A), the linear photodiode arrays (210) can be fabricated onto a transparent glass substrate (214) with patterned ITO (211) or other transparent electrode materials (such as conducting polymer electrodes, thin metal films, metal/conducting polymer bilayer electrodes dielectric film/ITO or metal film/dielectric film bilayer electrodes). The process of ITO patterning is well known in the existing art, and has been used broadly in LCD technologies. The deposition of the organic layer (212) can be achieved by spin casting, drop casting, printing, electrochemical synthesis or vapor deposition. The back electrode, in the form of a narrow bar shape (213), can be vacuum deposited with a simple shadow mask or patterned by means of photolithography. In most applications (especially for larger pixel sizes), no patterning of the sensing material is necessary. This sensing array can be mounted onto a print circuit (PC) board with a driving circuit. Several existing connection techniques (such as card-edge connectors, zebra connectors, bonding tapes, wire bonding, soldering bumper etc.) can be used for interboard connection. The drive circuits can also be arranged (surrounding the sensor array) onto the same substrate. This is especially preferred in arrays with a high pixel density (e.g., >80 pixels/inch). In these cases, the IC chips can be bonded to the glass substrate, and the electrical connections can be achieved via soldering, one-dimensional conducting epoxy or other existing connection technologies.
- As demonstrated in the examples herein, the spectral response of the polymer image sensors can cover the entire visible spectrum with relatively flat response. A portion of the visible spectrum can also be selected with a band-pass or low-pass optical filter. Multi-color detection in the visible and the near UV can be achieved by coupling the image sensor with a color-filter panel. A fabrication process for full-color image sensors is described with the x-y addressable polymer diode matrix and a RGB (red, green, blue) color filter panel. A similar fabrication process can be employed to prepare a linear photodiode array.
- Definitions and Device Structures
- In this description of preferred embodiments and in the claims, reference will be made to several defined terms. One group of terms concerns the structure of the voltage-switchable photodiode. A cross-sectional view of the voltage-switchable photodiode is shown in FIG. 1. The voltage-
switchable photodiode 10 is constructed using the metal-semiconductor-metal (M-S-M) thin film device configuration. Specifically, thedevice 10 includes: - A “photoactive layer” (layer12) comprised of organic, semiconducting material(s), such as a conjugated polymer, a polymer blend, a polymer/molecule polyblend, a layer of organic molecule or molecular blends; or a multilayer structure combining the above materials;
- Two “contact electrodes” (layers11, 13) which serve as the anode and cathode of the photodiodes to extract electrons and holes, respectively, from the photoactive layer. One of the electrodes (
layer 11 in FIG. 1) is made transparent or semitransparent in the spectral range of interest to allow the incident light 18 to be absorbed in the active layer (12). - The “anode” electrode is defined as a conducting material with higher work function than the “cathode” material.
- This same relationship of
electrodes active layer 12 and light source 18 (or 18′) is found indevices - As shown in FIGS. 1 and 2,
electrodes voltage source 15 vialines light 18. This same circuit would be employed in all of the devices (10, 20, 30, 40 and 50) depicted in FIGS. 1-5. - The devices may also include an optional substrate or
support 14, as shown in FIGS. 1-5. This is a solid, rigid or flexible layer designed to provide robustness to the diodes and/or to the matrix array of diodes. When light is incident from the substrate side, the substrate should be transparent or semitransparent in the spectral range of interest. Glass, polymer sheets or flexible plastic films are substrates commonly used. Wide band semiconductor wafers (such as SiC, SiN) which are transparent below their optical gaps can also be used in some applications. In these cases, a thin, doped region can also serve as thecontact electrode 11. - Devices with the inverted geometry shown in FIG. 2 are also useful in applications. In this configuration, light18 is incident from the “back” electrode side, and optically opaque materials can be used as the substrate material. For example, by using an inorganic semiconductor wafer (such as silicon) as the
substrate 14, and by doping the semiconductor to “conductive” levels (as defined in the following), the wafer can serve both as thesubstrate 14 and thecontact electrode 11. The inverted structure offers the advantage of integrating the photosensor with driving/read-out circuitry built directly onto the inorganic semiconductor substrate (using integrated circuit technology). - The incident light18 (or 18′) is defined generally so as to include wavelengths in visible (400-700 mn), wavelengths in the ultraviolet (200-400 nm), wavelength in the vacuum UV (<200 mn), and wavelengths in the infrared (700-2000 nm).
- Several layers are designated as “transparent” or “semi-transparent”. These terms are used to refer to the property of a material which transmits a substantial portion of the incident light incident on it. The term “transparent” is used to describe a substrate with transmittance over 50% and the term “semi-transparent” is used to describe a substrate with transmittance between 50% to 5%.
- A “conductive” layer or material has a conductivity typically larger than 0.1 S/cm. A semiconducting material has conductivity of from 10−14 to 10−1 S/cm.
- The “positive” (or “negative”) bias refers to the cases when higher potential is applied to the anode electrode (cathode electrode). When values of negative voltage are referred to, as in the case of the reverse bias voltages applied to obtain enhanced photosensitivity, the relative values will be stated in terms of absolute values; that is, for example, a −10 V (reverse) bias is greater than a −5 V (reverse) bias.
- The structure of the x-y addressable, passive photodiode matrix (2D image sensor30) is depicted in FIG. 3. Shown in FIG. 4 is the structure of a full-
color image sensor 40 made with the x-y addressable photodiode matrix. In these devices, the anode andcathode electrodes 11′, 13′ are typically patterned into rows and columns perpendicular to one another. Patterning of thephotoactive layer 13 is not necessary for pixels with sufficient space between adjacent electrodes. Each intersection of the row and column electrodes defines a photosensitive element (pixel) with device structure similar to that shown in FIG. 1 or FIG. 2. The widths of the row andcolumn electrodes 11′, 13′ define the active area of each pixel. - A matrix of color filters19 (each pixel of the color filter is comprised of red, green and
blue color filters 19′) is coupled with the photodiode panel. A separate sheet of color filters similar to that used for color-LCD displays [For a review, see: M. Tani and T. Sugiura, Proceeding of SID, Orlando, Fla. (1994)] can be used for this purpose. In a more preferred embodiment, the color-filter panel can be coated directly onto the substrate for the photodiode matrix. The set of transparent electrodes 11 (for example, made of indium-tin-oxide, ITO) can be fabricated over the color filter coating. In this configuration, high pixel densities with micron-size feature size can be achieved. - A coating of “black” material (opaque in the spectral range of interest) in the area between each sensing pixel can be placed in front of the photodetector plane, forming a “black matrix”. This coating is helpful in some situations to further reduce cross-talk between neighbor pixels in devices with an unpatterned photoactive organic layer. Black matrices have been used in CRT monitors and other flat panel displays to increase display contrast, and are well known in the display industry. The patterning of the “black matrix” can be achieved with standard photolithography, stamp, ink-jet or screen printing techniques.
- Full-color detection can be achieved with an
alternative approach 50 as shown in FIG. 5. In this approach, each full-color pixel 12′ comprises three photodiodes 12R, 12G and 12B with long wavelength cut-offs at 700, 600 and 500 nm, respectively. These photodiodes are made of three photosensitive materials in the defined areas on the substrate. The patterning of the active layers can be achieved by photolithography, screen printing, shadow masking and the like. The correct red, green and blue color information can be obtained by differentiation of the signals (in the read-out circuit) from the three sub-pixels, 12R, 12G and 12B, as demonstrated in the examples of this invention. An optically uniform material is used as the substrate which is transparent in the visible and opaque in UV. - The color selection can also be achieved by combining the device structure shown in FIG. 4 with that shown in FIG. 5. For instance, with the photosensing material in the photodiode defining part of the spectral response, the optical filter placed in front fine-tunes the response desired. Example 15 utilizes this approach for a photosensor simulating the response of the human eye.
- The Photoactive Layer
- The
photoactive layer 12 in the voltage-switchable photodiodes is made of a thin sheet of organic semiconducting material. The active layer can comprise one or more semiconducting, conjugated polymers, alone or in combination with non-conjugated materials, one or more organic molecules, or oligomers. The active layer can be a blend of two or more conjugated polymers with similar or different electron affinities and different electronic energy gaps. The active layer can be a blend of two or more organic molecules with similar or different electron affinities and different electronic energy gaps. The active layer can be a blend of conjugated polymers and organic molecules with similar or different electron affinities and different energy gaps. The latter offers specific advantages in that the different electron affinities of the components can lead to photoinduced charge transfer and charge separation; a phenomenon which enhances the photosensitivity [N. S. Sariciftci and A. J. Heeger, U.S. Pat. No. 5,333,183 (Jul. 19, 1994); N. S. Sariciftci and A. J. Heeger, U.S. Pat. No. 5,454,880 (Oct. 3, 1995); N. S. Sariciftci, L. Smilowitz, A. J. Heeger and F. Wudl, Science 258, 1474 (1992); L. Smilowitz, N. S. Sariciftci, R. Wu, C. Gettinger, A. J. Heeger and F. Wudl, Phys. Rev. B 47,13835 (1993); N. S. Sariciftci and A. J. Heeger, Intern. J. Mod. Phys.B 8, 237 (1994)]. The active layer can also be a series of heterojunctions utilizing layers of organic materials or blends as indicated above. - The thin films of organic molecules, oligomers and molecular blends can be fabricated with thermal evaporation, chemical vapor deposition (CVD) and so on. Thin films of conjugated polymers, polymer/polymer blends, polymer/oligomer and polymer/molecule blends can often be fabricated by casting directly from solution in common solvents or using similar fluid phase processing. When polymers or polyblends are used as the active layer, the devices can be fabricated onto flexible substrates yielding unique, mechanically flexible photo sensors.
- Examples of typical semiconducting conjugated polymers include, but are not limited to, polyacetylene, (“PA”), and its derivatives; polyisothianaphene and its derivatives; polythiophene, (“PT”), and its derivatives; polypyrrole, (“PPr”), and its derivatives; poly(2,5-thienylenevinylene), (“PTV”), and its derivatives; poly(p-phenylene), (“PPP”), and its derivatives; polyflourene, (“PF”), and its derivatives; poly(phenylene vinylene), (“PPV”), and its derivatives; polycarbazole and its derivatives; poly(1,6-heptadiyne); polyisothianaphene and its derivatives; polyquinolene and semiconducting polyanilines (i.e. leucoemeraldine and/or the emeraldine base form). Representative polyaniline materials are described in U.S. Pat. No. 5,196,144 which is incorporated herein by reference. Of these materials, those which exhibit solubility in organic solvents are preferred because of their processing advantages.
- Examples of PPV derivatives which are soluble in common organic solvents include poly(2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene), (“MEH-PPV”) [F. Wudl, P. -M. Allemand, G. Srdanov, Z. Ni and D. McBranch, in Materials for Nonlinear Optics: Chemical Perspectives, edited by S. R. Marder, J. E. Sohn and G. D. Stucky (The American Chemical Society, Washington D.C., 1991), p. 683.], poly(2-butyl-5-(2-ethyl-hexyl)-1,4-phenylenevinylene), (“BuEH-PPV”) [M. A. Andersson, G. Yu, A. J. Heeger, Synth. Metals 85, 1275 (1997)], poly(2,5-bis(cholestanoxy)-1,4-phenylenevinylene), (“BCHA-PPV”) [see U.S. patent application Ser. No. 07/800,555, incorporated herein by reference] and the like. Examples of soluble PTs include poly(3-alkylthiophenes), (“P3AT”), wherein the alkyl side chains contain more than 4 carbons, such as from 5 to 30 carbons.
- Organic image sensors can be fabricated using donor/acceptor polyblends as the photoactive layer. These polyblends can be blends of semiconducting polymer/polymer, or blends of semiconducting polymer with suitable organic molecules and/or organometallic molecules. Examples for the donor of the donor/acceptor polyblends include but are not limited to the conjugated polymers just mentioned, that is PPV, PT, PTV, and poly(phenylene), and their soluble derivatives. Examples for the acceptors of the donor/acceptor polyblends include but are not limited to poly(cyanaophenylenevinylene) (“CN-PPV”), fullerene molecules such as C60 and its functional derivatives, and organic molecules and organometallic molecules used heretofore in the art for photoreceptors or electron transport layers.
- One can also produce photoactive layers using two semiconducting organic layers in a donor/acceptor heterojunction (i.e., bilayer) structure or alternation layer structures. In these structures, the donor layer is typically a conjugated polymer layer and the acceptor layer is made up of poly(cyanaophenylenevinylene) (“CN-PPV”), fullerene molecules such as C60 and its functional derivatives (such as PCBM and PCBCR), or organic molecules used heretofore in the art for photoreceptors and electron transport layers. Examples of this heterojunction layer structure for a photoactive layer include but are not limited to, PPV/C60, MEH-PPV/C60, PT/C60, P3AT/C60, PTV/C60 and so on.
- The active layer can also be made of wide band polymers such as poly-N-vinylcarbazole (“PVK”) doped with dye molecule(s) to enhance photosensitivity in the visible spectral range. In these cases, the wide band organic serves as both host binder as well as hole (or electron) transport material. Examples include, but are not limited to, PVK/o-chloranil, PVK/rhodamine B and PVK/coronene and the like.
- The photoactive layer can employ organic molecules, oligomers or molecular blends. In this embodiment, the photosensitive material can be fabricated into thin films by chemical vapor deposition, molecular epitaxy or other known film-deposition technologies. Examples of suitable materials include but are not limited to include anthracene and its derivatives, tetracene and its derivatives, phthalocyanine and its derivatives, pinacyanol and its derivatives, fullerene (“C60”) and its derivatives, thiophene oligomers (such as sixethiophene “6T” and octithiophene “8T”) and their derivatives phenyl oligomers (such as sixephenyl “6P” or octiphenyl “8P”) and their derivatives, aluminum chelate (Alq3) and other metal-chelate molecules (m-q3), PBD, spiro-PBD, oxadiazole and its derivatives and blends such as 6T/C60, 6P/C60, 6P/PBD, 6P/Alq3, 6T/pinacyanol, phthalocyanine/o-chloranil, anthracene/C60, anthracene/o-chloranil. For the photoactive layer containing more than two types of molecules, the organic layer can be in a blend form, in bilayer form or in multiple alternate layer forms.
- In some embodiments, the active layer comprises one or more organic additives (which are optically non-active) to modify and to improve the device performance. Examples of the additive molecules include anionic surfactants such as ether sulfates with a common structure,
- R(OCH2CH2)nOSO3 −M+
- wherein R represents alkyl alkyllaryl,
- M+ represents proton, metal or ammonium counterion,
- n is moles of ethylene oxide typically n=2-40).
- Application of such anionic surfactants as additives for improving the performance of polymer light-emitting diodes has been demonstrated by Y. Cao [U.S. patent application, Ser. No. 08/888,316, which is incorporated by reference].
- Other types of additives include solid state electrolytes or organic salts. Examples include poly(ethylene oxide), lithium trifluoromethanesulfonate, or their blends, tetrabutylammonium dodecylbenzenesulfonate and the like. Application of such electrolyte to luminescent polymers and invention of new type of light-emitting devices have been demonstrated in U.S. Pat. Nos. 5,682,043 and 5,677,546.
- In cases where the active layer is made of organic blends with two or more phases with different electron affinities and optical energy gaps, nanoscale phase separation commonly occurs, and heterojunctions form at the interfacial area. The phase(s) with higher electron affinity acts as an electron acceptor(s) while the phases with lower electron affinity (or lower ionization energy serves as an electron donor(s). These organic blends form a class of charge-transfer materials, and enable the photo-initiated charge separation process defined by the following steps [N. S. Sariciftci and A. J. Heeger, Intern. J. Mod. Phys.
B 8, 237 (1994)]: - Step 1: D+A″1,3D*+A, (excitation on D);
- Step 2:1,3D*+A″1,3(D−A)*, (excitation delocalized on D−A complex);
- Step 3:1,3(D−A)*″1,3(Dd+−Ad−)*, (charge transfer initiated);
- Step 4:1,3(Dd+−Ad−)*″1,3(D+°−A−°), (ion radical pair formed);
- Step 5:1,3(D+°−A−°)″D+°+A−°, (charge separation)
- where (D) denotes the organic donor and (A) denotes the organic acceptor; 1,3 denote singlet or triplet excited states, respectively.
- Typical thickness of the active layer range from a few hundred Ångstrom units to a few thousand Ångstrom units; i.e., 100-5000 Å(1 Ångstrom unit=10−8 cm). Although the active film thicknesses are not critical, device performance can typically be improved by using thinner films with optical densities of less than two in the spectral region of interest.
- Electrodes
- As shown in FIGS. 1 and 2, the organic photodiodes of this invention are constructed in an M-S-M structure, in which the organic photoactive layer is bounded on two sides with conductive contact electrodes. In the configuration shown in FIG. 1, a
transparent substrate 14 and atransparent electrode 11 are used as one contact electrode. Indium-tin-oxides (“ITO”) can be used as theelectrode 11. Other transparent electrode materials include aluminum doped zinc oxides (“AZO”), aluminum doped tin-oxides (“ATO”), tin-oxides and the like. These conducting coatings are made of doped metal-oxide compounds which are transparent from near UV to mid-infrared. - The
electrode 11 can also be made with other doped inorganic compounds or alloys. These compounds can be doped into metallic (or near metallic) form by varying the composition of the elements involved, the valance of the elements or the morphology of the films. These semiconducting or metallic compounds are known in the art and are well documented (e.g., N. F. Mott, Metal-Insulating Transitions, 2nd edition (Taylor & Francis, London, 1990); N. F. Mott and E. A. Davis, Electronic Processes in Non-crystalline Materials (Claredon, Oxford, 1979)]. Examples of such compounds include the cuprate materials which possess superconductivity at low temperatures (so-called high temperature superconductors). - The
electrode 11 in FIG. 1 (or 13 in FIG. 2) can be formed of a conductive polymer such as polyaniline in the emeraldine salt form prepared using the counterion-induced processability technology disclosed in U.S. Pat. No. 5,232,631 and in Appl. Phys. Lett. 60, 2711 (1992) or other suitable techniques. The polyaniline film which serves as the electrode can be cast from solution with high uniformity at room temperature. The organic conducting electrodes in combination with polymer substrates and organic active layers allow these photosensors be fabricated in fully flexible form. Other conductive polymers can be used for the transparent or semitransparent electrode (11 in FIG. 1 or 13 in FIG. 2) include polyethylene dioxythiophene polystyrene sulfonate, (“PEDT/PSS”) [Y. Cao, G. Yu, C. Zhang, R. Menon and A. J. Heeger, Synth. Metals, E, 171 (1997)], poly(pyrrole) or its function derivatives doped with dodecylbenzene sulfonic acid (“DBSA”) or other acid [J. Gao, A. J. Heeger, J. Y. Lee and C. Y. Kim, Synth. Metals 82, 221 (1996)] and the like. - A thin semitransparent layer of metals (such as Au, Ag, Al, In etc.) can also be used as the
electrode 11 in FIG. 1 and 13 in FIG. 2. Typical thicknesses for this semitransparent metal electrode are in the range of 50-1000 Å, with optical transmittance between 80% and 1%. A proper dielectric coating (often in the form of multilayer dielectric stacks) can enhance the transparency in the spectral range of interest [For examples, see S. M. Sze, Physics of Semiconductor Devices (John Wiley & Sons, New York, 1981) Chapter 13]. - A transparent electrode can also be made from metal/conducting polymer, conducting polymer/metal/conducting polymer or dielectric layer/metal/conducting polymer structures. The transmission properties of these composite electrodes are improved relative to that of a single metal layer of the same thickness.
- A metal layer with low optical transmittance can also be used as the
electrode 11 for some applications in which spectral response at certain wavelengths is of interest. The photosensitivity can be enhanced by fabricating the device in a micro-cavity structure where the twometal electrodes - The “back”
electrode 13 in FIG. 1 (and 11 in FIG. 2) is typically made of a metal, such as Ca, Sm, Y, Mg, Al, In, Cu, Ag, Au and so on. Metal alloys can also be used as the electrode materials. These metal electrodes can be fabricated by, for example, thermal evaporation, electron beam evaporation, sputtering, chemical vapor deposition, melting process or other technologies. The thickness of theelectrode 13 in FIG. 1 (and 11 in FIG. 2) is not critical and can be from hundreds of Ångstroms to hundreds of microns or thicker. The thickness can be controlled to achieve a desired surface conductivity. - When desired, for example, for a photodiode with detectivity on both front and back side, the transparent and semi-transparent materials described above can also be used as the “back”
electrode 13 in FIG. 1 (and 11 in FIG. 2). - The patterning of the row and column electrodes shown in FIG. 3 and FIG. 4 can be achieved by standard patterning technologies well-known in semiconductor industry such as shadow masking, photolithographing, silk-screen printing or stamp (microcontact) printing etc. These methods are well known to those knowledgeable of the art of display and image sensor technologies.
- To improve the device performance (for example, device lifetime, operation speed etc.), a buffer layer comprising conducting polymers or blends containing them can be inserted in between the electrode11 (or 13) and the photoactive layer. The conductivity of the buffer layer can be chosen from a broad range (between that of the pure conducting polymer and the photoactive material). Conductivity of the buffer layer is changed by processing conditions of the conducting polymer (counter-ion, solvent, concentration etc.) and the composition ratio of the blend. In certain situations the thickness of the buffer layer also affects the spectral response of the photosensor.
- Color Filter Coating
- In some applications, multicolor detection or selected color detection are of interest. These can be achieved by properly selecting the material for the photoactive layer along with coupling the photosensor with a color filter coating.
- One type of application is a photosensor with selected spectral response, for example, from 500 to 600 nm. One effective approach is taking an organic photodiode with low energy cut-off at 600 nm (for example, a photodiode made with MEH-PPV), and placing a long-wavelength, low pass optical filter (with cut-off at 500 nm) in front. The spectral response of semiconducting oligomers and polymers can be controlled by modifying the side chain or main chain structures. For example, by varying the side chain of the PPV system, the optical gap can be tuned from 500 nm to 700 nm. An alternative approach to achieving bandpass selection is to place a bandpass optical filter in front of an organic photodiode with wider spectral response.
- In photoimaging applications, full-color detection is frequently of interest. This can be achieved by splitting a sensor element (pixel) into three subpixels with response to red (600-700 nm), green (500-600 nm) and blue (400-500 nm) (R, G, B) spectral regions (as shown in FIG. 4) respectively, similar to that commonly used in liquid crystal display (LCD) color-display technologies.
- A simple but effective approach to full-color image sensors is sketched in FIG. 4. In this approach, the photodiode matrix is made of single sheet of active layer without patterning. The active areas are defined by the row and column electrodes. The spectral response of these organic photodiodes should cover the entire visible region (400-700 nm). Color selection is achieved by the color filter panel in front of the transparent electrodes. There are many organic materials or blends with photoresponse covering the entire visible spectrum. Examples include PT derivatives such as “P3AT” [G. Yu, et al., Phys. Rev. B42, 3004 (1990), “POPT”, poly(3-(4-octylphenyl)thiophene) [M. R. Andersson, D. Selese, H. Jarvinen, T. Hjertberg, 0. Inganas, 0. Wennerstrom and J. E. Osterholm,
Macromolecules 27, 6503 (1994)], PTV and its derivatives and the like. - Several color filter techniques have been developed and have been used broadly in color displays made with liquid crystal technologies, including dyeing, pigment-dispersed, printing and electro-deposition [M. Tani and T. Sugiura, Digest of SID 94 (Orlando, Fla.)]. Another approach uses multilayer dielectric coating based on optical interference. Because of better stability, pigment dispersion has become the major process used in large-scale manufacturing. Color filter panels with designed patterns, often in arrangements in triangular, striped (similar to that shown in FIG. 4), or diagonal mosaics, with transparent electrode coating (such as ITO) are existing art and are commercially available to the display industry. This type of substrate can be used in the fabrication of full-color image sensors shown in FIG. 4.
- The photodetectors provided by the present invention can be adapted to respond to various types of ionized particles in addition to photons, themselves. This can be accomplished by incorporating in the photodetector structure a scintillating material adapted to emit photons in response to ionized particles. This material can be present in admixture with the active layer, it can be present as a separate layer or it can be present as part of the substrate or the transparent electrode. In one example this scintillating material is a phosphor, present, for example as a phosphor layer.
- Examples of ionized particles which may be detected with devices of this structure are high energy photons, electrons, X-rays and ionized particles are characteristic of X-rays, beta particles and ionized particles are characteristic of gamma radiation.
- Applications of the Invention
- The invention of voltage-switchable organic photodiodes provides the foundation for fabrication of large size, low cost 2D image sensors based on x-y addressable passive diode matrices. This type of photodiode shows high photosensitivity (typically in the range of 30-300 mA/W), quantum efficiency (even over 100% electrons/photon at given reverse biases) and virtually zero response at a bias voltage close to the built-in potential. Thus, a row of pixels in a column-row matrix of such photodiodes can be selected by setting the selected row at reverse bias and the pixels on the other row biased at a voltage close to the built-in potential. In this way, crosstalk from pixels in different rows is eliminated. The image information at the pixels in the selected row can be read-out correctly in both the serial mode or the parallel mode. The information on the pixels in the other rows can be read-out in sequence or in selected fashion by setting the row of interest to reverse bias. The x-y addressable organic photodiode matrices provide a new type of 2D image sensor which can be made in large size, with low fabrication cost, onto substrates in desired shape or flexible, and hybridizable with other optical or electronic devices.
- Specific advantages of this invention over the prior art include the following:
- (i) Organic photosensors with switchable photosensitivity. High photosensitivity can be switched on (typically in the range of 30-300 mA/W) at a selected reverse biasing voltage. The photosensitivity can be switched off effectively when the diode is biased externally at a voltage closed to that corresponding to the internal potential.
- (ii) 2D, x-y addressable, passive image sensors fabricated with the organic photodiodes with switchable photosensitivity. Crosstalk-free read-out can be achieved with these passive image sensors by means of proper electronic pulse sequences.
- (iii) Multi-color detection and full-color image sensing can be achieved by coupling the image matrix with a color filter panel or by fabricating the image sensor matrix directly onto a color filter panel.
- (iv) Organic photodetector arrays in combination with other known advantages which characterize devices made with organic materials such as soluble conjugated polymers (ease in fabrication into large areas and desired shapes on rigid or flexible substrates, room temperature processing, ease in hybridization with optical, electro-optical, opto-electric or electric devices) offer promise for large size, low cost, high pixel density, 1D or 2D image sensors for use in office automation, in industrial automation, in biomedical devices and in consumer electronics.
- Voltage-switchable photodiodes were fabricated by evaporating a 5000 Å calcium contact (13) on the front of a thin MEH-
PPV film 12 which was spin-cast from solution onto a ITO/glass substrate 14. The glass substrate had been previously partially coated with acontact layer 11 of indium-tin-oxide (ITO). The active area of each device was 0.1 cm2. The MEH-PPV film was cast from a 0.5% (11 mg/2 ml) xylene solution at room temperature. Details on the synthesis of MEH-PPV can be found in literature [F. Wudl, P. M. Allemand, G. Srdanov, Z. Ni, and D. McBranch, in Materials for Nonlinear Optics:Chemical Perspectives, Ed. S. R. Marder, J. E. Sohn and G. D. Stucky (American Chemical Society, Washington, D.C., 1991) p. 683]. The thickness of the active layer was adjusted by varying the concentration of the solution, by varying the spin speed of the spinner head and by applying multiple coating layers. - Electrical data were obtained with a Keithley 236 Source-Measure Unit. The excitation source was a tungsten-halogen lamp filtered with a bandpass filter (center wavelength of 430 nm, bandwidth of 100 nm) and collimated to form a homogeneous 5 mm×10 mm area of illumination. The maximum optical power at the sample was 20 mW/cm2 as measured by a calibrated power meter. A set of neutral density filters were used for measurements of intensity dependence.
- FIG. 6 shows the magnitude of the photocurrent (absolute value) as a function of bias voltage under 20 mW/cm2 illumination at 430 nm. The photocurrent at 1.5 V bias was ˜3×10−8 A/cm2,increasing to 9×10−4 A/cm2 at −10 V reverse bias corresponding to a photosensitivity of 45 mA/W and a quantum efficiency of 13% el/ph. The ratio of the photosensitivity between the two bias voltages was 3×104, thus the photosensitivity at 1.5 V bias was practically zero in the read-out circuit. This degree of difference enabled an analog-to-digital (A/D) convertor of 8-12 bit resolution.
- The photoresponse increased nearly linearly with light intensity (I0.921−1) over the entire range measured from nW/cm2 to tens mW/cm2. No signature of saturation was observed at 20 mW/cm2 (the highest light intensity in the measurement).
- Other metals such as Al, In, Cu, Ag and the like were also used for the counterelectrode13 (see FIG. 1) which is the cathode in these devices. Similar photosensitivities to that shown in FIG. 5 were observed in all these devices. The off-state voltage which balanced off the internal potential of the photodiode varied with the work function of the metal; the off-state voltage is determined by the work function difference between the metal cathode and the ITO anode. Table 1 lists the off-state voltage found for MEH-PPV photodiodes with several metal electrodes.
- This experiment was also repeated with a thin layer (0.5-20 nm) of one of the metals listed in Table 1 with a thick Al layer deposited on top as a current conducting layer. The device performance is similar to that discussed above, with the off-state voltage mainly determined by the thin metal layer at the interface.
- Devices were also fabricated with other photoactive organic materials, including P3AT, POPT, PTV, PPV, BuEH-PPV, BUHP-PPV, C60, 6T, 6P, spiro-6P, Alq3, anthracene and phthalocyanine. Similar results to those shown in FIG. 6 were observed.
- This example demonstrates that high photosensitivity can be achieved with MEH-PPV organic photodiodes under reverse bias. The desired photosensitivity can be achieved at a given reverse bias. The photosensitivity can be switched off at a proper bias voltage which is dependent on the electrode materials selected. As shown in Table 1, air stable metals with work functions over 4 V can be used for the electrodes in organic photodiodes. This example also demostrates that the off-state voltage is determined by the work function of the electrode close to the interface area. This example also demonstrates the broad dynamic range of the polymer photodiodes, a dynamic range which is sufficient to enable image detection with multi-grey levels.
TABLE 1 Off-state voltage in ITO/MEH-PPV/metal photodiodes Metal cathode Ca Sm Yb Al In Ag Cu Voff(V) 1.5 1.5 1.5 1.1 0.9 0.7 0.4 - Devices of Example 1 were fabricated onto flexible ITO/PET substrates. The thickness of the PET sheets used as substrates was 5-7 mils (125-175 μm). Similar device performance was observed.
- This example demonstrates that the voltage-switchable organic photodiodes can be fabricated in a thin structure, in flexible form, or in a desired shape to meet the special needs in specific applications.
- Devices of Example 1 were fabricated on glass and PET substrates. In these devices, the
ITO anode 11 was replaced with organic conducting coatings or with ITO overcoated with conducting organic films. PANI-CSA and PEDT/PSS were used as the organic electrode. The PANI-CSA layers were spin-cast from m-cresol solution [details about preparation of the PANI solution and PANI-CSA film have been disclosed in U.S. Pat. No. 5,232,631]. The PEDT-PSS films were cast from an aqueous dispersion (1.3% W/W) which was supplied by Bayer [Bayer trial product, TP AI 4071], details about the synthesis can be found in the literature [G. Heywang and F. Jonas, Adv.Materials 4, 116 (1992)]. The cast films were then baked at 50-85° C. for several hours in a vacuum oven or in a N2 dry box. In the case of PEDT/PSS, the films were finally baked at a temperature over 100° C. for several minutes to complete the drying process. The thickness of the conducting polymer electrodes was controlled from a few hundred Angstroms to a few thousand Angstroms. - The optical transmission spectra of the polymer anode electrodes are shown in FIG. 7, including data from PANI-CSA and PEDT-PSS. Also shown in FIG. 7 is the spectral response of the normal human eye, V(λ). The data indicate that these organic conducting electrodes can be used for photosensors for applications in visible spectral range. Moreover, the PEDT-PSS electrodes can also be used for ultraviolet (250-400 mn) and for near infrared. Thus, the polymer electrodes can be used in photosensors with full-color (white color or R, G, B three color) detection.
- In addition to the electrodes made with PANI-CSA or PEDT-PSS alone, devices were fabricated with ITO/PANI-CSA and ITO/PEDT-PSS bilayer electrodes. In these cases, the polymer electrodes were cast in a thin layer (thickness of a few hundred Angstrom units) to maximize the optical transmission. Organic light-emitting devices with bilayer electrodes have demonstrated improved device performance such as carrier injection and device stability. Examples are shown in U.S. patent applications Ser. Nos. 08/205,519 and 08/609,113.
- The photosensitivities of the devices with organic anode electrodes or bilayer electrodes were similar to those shown in FIG. 6; i.e. tens of mA/W at reverse bias voltage in the −5 to about −10 V range.
- This example demonstrates that conducting polymer materials can be used as the transparent electrodes of the photodiodes and image sensors. These plastic electrode materials provide the opportunity to fabricate organic photosensors in flexible or foldable forms. This example also demonstrates that the polymer electrode can be inserted between a metal-oxide transparent electrode (such as ITO) and the active layer to modify the interfacial properties and the device performance.
- Devices of Example 1 were repeated. A thin buffer layer was inserted between the ITO and the MEH-PPV layers to reduce the leakage current through pinhole imperfections in the active layer. The materials used for the buffer layer were PAZ, TPD (prepared via chemical vapor deposition) and PVK (cast from cyclohexanone solution). The thickness of the buffer layer was 100-500 Å. The photoresponse of these devices was similar to that shown in FIG. 6. However, in these devices, the dark current (which is caused frequently from microshorts due to pinholes in the active layer) was reduced in magnitude. In these short-free devices, a photon flux as small as 1 nW/cm2 was detected under direct current operation. The off-state voltage was 1.6˜1.7 V in these devices, slightly higher than in the devices in Example 1.
- This example demonstrates that a buffer layer can be inserted between the active layer and the contact electrode(s) to reduce device shorts and to improve the device response to weak light. This buffer layer can be made of organic molecules via chemical vapor deposition or polymeric materials through wet casting processes.
- Devices of Example 1 were repeated. The active material, MEH-PPV, was blended with an anionic surfactant Li-CO436 in molar ratios of 0, 1, 5, 10 and 20%. The Li-CO436 was synthesized by a substitution reaction from Alipal CO436 (ammonium salt nonylphenoxy ether sulfate) supplied by Phone-Poulenc Co. [Y. Cao, U.S. patent application Ser. No. 08/888,316]. Al was used as the cathode. The photosensitivity was enhanced in the devices with blended Li-CO436. For example, the photocurrent increased by a factor of 2 in a device made with MEH-PPV:Li-OC436 (10 wt %) compared with a similar device made without the Li-OC436. Moreover, the off-state voltage shifted from 1.1 V in ITO/MEH-PPV/Al devices (see Example 1) to 1.5 V in the ITO/MEH-PPV:Li-OC436 (20%)/Al devices. Similar effects were also observed in devices having an ITO/MEH-PPV/Li-OC436/Al structure. The off-state voltage increases from 1.1 V to 1.6 V.
- Devices of Example 1 were also fabricated with LiF, Li2O or BaO layers (1-30 nm) inserted between the MEH-PPV and the Al cathode. Similar enhancement of the short circuit current and the off-state voltage was observed.
- Devices of Example 1 were also fabricated with a TiO2 layer (1-30 nm) inserted between the MEH-PPV and the Al cathode, and with TiO2 nanoparticles dispersed in the MEH-PPV film (forming a phase separated MEH-PPV:TiO2 blend film. Similar results to those obtained with ITO/MEH-PPV/BaO/Al were observed.
- This example demonstrates that organic additives can be added to the active layer or inserted between the active player and the contact electrode to modify the device performance including photosensitivity and off-state voltage. This example also demonstrates that a layer of inorganic dielectric or semiconducting compounds can be inserted between the active layer and the contact electrode to modify device performance, including photosensitivity and off-state voltage. The inorganic dielectric or semiconducting compounds can also be made in nanoparticle form and blended with the organic photosensing materials.
- Voltage-switchable photodiodes were fabricated in the structure of ITO/MEH-PPV:PCBM/metal, similar to that shown in FIG. 1. The PCBM (a C60 derivative) served as an acceptor in a donor-acceptor pair with the MEH-PPV acting as donor. The active area of these devices was ˜0.1 cm2. The blend solution was prepared by mixing 0.8% MEH-PPV and 2% PCBM/xylene solutions with 2:1 weight ratio. The solution was clear, uniform, and was processable at room temperature. Solutions were stored in a N2 box for over 1.5 years and no aggregation or phase separation were observed. The active layer was spin-cast from the solution at 1000-2000 rpm. Typical film thicknesses were in the range of 1000˜2000 Å. Ca, Al, Ag, Cu, and Au were used as the
counter electrode 13. In each case, the film was deposited by vacuum evaporation with thickness of 1000-5000 Å. In another experiment, the concentration of the acceptor PCBM was varied from 0 to 1:1 molecular ratio. Higher on state photosensitivity and lower on-state operation voltage were observed in devices with higher concentrations. - FIG. 8 shows the I-V characteristics of an ITO/MEH-PPV:PCBCR/Al device in the dark and under light illumination. The thickness of the blend film was ˜2000 Å. The dark current saturated at ˜1 nA/cm2 below 3 V and then increased superlinearly at high bias voltages (>Eg/e). Zener tunneling can account for this effect. The photocurrent was measured. The photocurrent at 0.65 V was ˜1×10−7 A/cm2, increasing to 5×104 A/cm2 at −10 V bias. The on-off ratio was ˜500. Devices with thinner blend films showed improved photosensitivity and higher on-off ratio. Similar photosensitivity was also observed in devices fabricated with other metals or metal alloys as the counter electrodes. These included Ag, Cu, Ca, Sm, Pb, Mg, LiAl, MgAg, BaAl.
- Other organic molecules were used as the photoacceptor, including C60. Other mixtures were prepared using the C60 derivative, PCBM with different solvents. Higher photosensitivity was observed from MEH-PPV:PCBM processed from 1,2-dichlorobenzene solution. The photosensitivity reached 0.2 A/W at 430 nm when biased at −2 V.
- This example demonstrates that the photosensitivity can be further improved by blending a donor polymer with a molecular acceptor such as C60, PCBM, PCBCR. High photosensitivity can be achieved at relatively low bias and low field (˜105 V/cm). This example also demonstrates that the photosensitivity can be switched to nearly zero when bias the device at a voltage balancing the internal built-in potential (˜0.65 V for Al cathode). The data in this example show that, due to its low dark current level, the polymer photodiode can be used to detect weak light down to intensity level of tens of nW/cm2. Thus, the polymer photodiodes have a dynamic range spanning more than six orders of magnitude, from nW/cm2 to 100 mW/cm2.
- Devices similar to those of Example 6 were fabricated with glass/ITO and PET/ITO substrates in 4.5 cm×4 cm (18 cm2) and in 3.8 cm×6.4 cm (24.3 cm2) using a fabrication process similar to that of Example 6. I-V characteristics similar to that shown in FIG. 8 were observed. The photodiodes made with flexible PET substrates were bent into circular shapes any without change in their photosensitivity.
- This example demonstrates that the high sensitivity, voltage-switchable photosensors can be fabricated in large sizes. With flexible PET substrates, the photosensors can be bent into desired shapes for special needs in optics, physics and biomedical fields.
- Devices similar to those of Example 6 were repeated with the active layer made of MEH-PPV:CN-PPV, a polyblend with two polymers as the donor and acceptor phases. Ca and ITO were used as the cathode and anode electrodes, respectively. The molecular ratio between this donor and the acceptor was varied from pure MEH-PPV (1:0) to pure CN-PPV (0:1). Similar I-V characteristics to those shown in FIG. 8 were observed in devices with intermediate molecular ratios. The off-state voltage shifted to ˜1.2 V as anticipated from the change in the potential barrier between the donor and acceptor phases.
- Devices similar to those of Example 6 were repeated with the active layer made of sexithiophene (6T):PCBCR, a blend with two organic molecules as the donor and acceptor phases. Similar I-V characteristics were obtained to those shown in FIG. 8.
- Devices were fabricated in the form of ITO/6P/C60/Al, ITO/6P/t-Bu-PBD/Al. The photoactive layer comprised two types of organic molecules in heterojunction form, made by thermal evaporation. Similar I-V characteristics to those shown in FIG. 8 were observed.
- Examples 8 and 9 demonstrate that the active layer of the voltage-switchable photodiodes can be organic molecules arranged in bilayer or multilayer structures, a blend of organic molecules, or a blend of conjugated polymers, in addition to a polymer/molecule blend as demonstrated in example 6. The data in these examples along with that in the Example 1 also demonstrate that, for a given cathode such as Ca, the off-state voltage varies with the electronic structure of the active material.
- Voltage-switchable organic photodiodes was fabricated with P3OT as the active layer in an ITO/P3OT/Au structure. The I-V characteristics in the dark and under light illumination are shown in FIG. 9. Since the work function of Au is higher than ITO, the Au electrode serves as the anode in these devices. Positive bias was defined such that a higher potential was applied to Au electrode. Light was incident from the cathode (ITO) electrode. In this experiment, a He—Ne laser at 633 nm was used as the illumination source with a photon density of 10 mW/cm2.
- The built-in potential in this photodiode was reduced to nearly zero volts. Thus, the off-state of the photodiode was shifted to close to zero volts. The photocurrent at −12 V was 1 mA/cm2, which was 104 times higher than that at zero bias. Values of the ratio Iph(−12V)/Iph(0) in excess of 1.5×105 have been realized in similar devices. The photosensitivity at 633 nm was ˜100 mA/W, corresponding to a quantum efficiency of ˜20% ph/el. The dark current in the test range was below 5×10−7 A/cm2. The photocurrent/dark current ratio was greater than 1000 over a broad bias range (−4˜−12 V).
- This example demonstrates that the off-state of the photodiode can be varied by proper selection of the active material and the electrode materials. This voltage can be set to a voltage close to zero volts. A photodiode matrix fabricated with this type of photodiode can be driven by pulse trains with mono-polarity, thus simplifying the driving circuitry. The large on/off switching ratio and the large photocurrent/darkcurrent ratio permit the photodiodes to be used in the fabrication of x-y addressable passive matrices with high pixel density and with multiple-gray levels.
- Two-dimensional, photodiode matrices were fabricated with seven rows and 40 columns. Pixel size was 0.7 mm×0.7 mm. The space between the row electrodes and the column electrodes was 1.27 mm (0.05″). The total active area was ˜2″×0.35″. Typical I-V characteristics from a pixel are shown in FIG. 10. White light from a fluorescent lamp on the ceiling of the lab was used as the illumination source with intensity of ˜tens of μW/cm2. This is much weaker than the light intensity used in document scanners.
- This example demonstrates that pixelated photodiode matrices can be fabricated without shorts and without crosstalk. This example also demonstrates that these devices can be used for applications with light intensities equal to or much less than a microwatt/cm2. Thus, polymer photodiode matrices are practical for image applications under relatively weak light conditions.
- A scanning scheme for the photodiode matrix was developed (see FIG. 11). Due to the strong voltage dependence of the photosensitivity, a column of pixels in the 2D photodiode matrix could be selected and turned on with proper voltage bias, leaving the pixels in the adjacent rows insensitive to the incident light. Under such operation, the physical M row, N column 2D matrix is reduced to N isolated M element linear diode arrays which are free from crosstalk between columns. This is reminiscent of the concept that is used in solving a 2D integral by dimension reduction, ∫f(x,y)dxdy=∫g(x)dx∫h(y)dy. With such 2D, passive photodiode arrays, an image can be read out with a pulse train scanning through each column of the matrix.
- FIG. 11 shows a instantaneous “snap-shot” of the voltage distribution in a 7×40 photodiode matrix. At a specific time t, all the pixels were biased at +0.7 V except the pixels in
column 1. The pixels incolumn 1 were all biased at −10 V so as to achieve high photosensitivity (tens-hundreds of mA/Watt). The information at each of the pixels incolumn 1 was read-out in both parallel (with N channel converting circuits and A/D converters) or serial (with N channel analog switches) sequences. Pixels in other columns were selected by switching the column bias from +0.7 V to −10 V in sequence. A digital shift register was used for the column selection. - To simplify the driver circuit, it was preferable that the photosensor can be switched on and off between 0 V and a reverse bias voltage (−2 to −10 V). Such a mono-polarity, voltage-switchable photodiode was demonstrated with ITO/P3OT/Au, as shown in Example 10.
- An image of multi-gray levels was selected, the image was scanned with the 7×40 photodiode matrix following the scanning scheme discussed in Example 12. The original image and the readout image were recorded photographically. The readout image reproduced the original image with excellent fidelity.
- This example demonstrates that the voltage-switchable photodiodes can be used as the pixel elements of a column-row matrix (as shown in FIG. 3). The photodiodes at each pixel can be addressed effectively from the column and row electrodes. Image information with multiple gray-levels can be read-out without distortion.
- Devices similar to those of Example 10 were fabricated and their spectral response was measured at a reverse bias of −15V. The data are shown in FIG. 12. In contrast to the significant sensitivity decrease at short wavelength in conventional inorganic photodiodes, the P3OT photodiodes exhibited relatively flat response for wavelengths shorter than 630 nm; the apparent decrease in sensitivity below 350 nm was mainly due to the transmission cut-off of the ITO coated glass substrate. For −15 V bias, the sensitivity at 540 nm reached 0.35 A/W (a quantum yield of ˜80% el/ph), the same value as obtained with UV-enhanced Si diodes. Similar photosensitivity values persisted into the UV region below 400 nm. In some devices, quantum efficiency of over 100% el/ph (140˜180% el/ph) was observed under reverse bias.
- Devices were also fabricated in the form of ITO/P3HT/P3HT:PCBM/A1. White light was used as the illumination source. Quantum efficiency of over 100% electrons/photon was observed. The highest value observed was ˜1100% electrons/photon. A gain mechanism may play a role in these multilayer devices.
- This example demonstrates high photosensitivity organic photodetectors with response covering, simultaneously, the near UV and the entire visible spectra. This example also demonstrates that organic photodetectors in the metal/organic/metal sandwich structure can have quantum efficiency over 100% electrons/photon; i.e., possesses a gain mechanism.
- Voltage-switchable photodiodes were fabricated to achieve a response similar to the visual response of the human eye, V(λ). The devices were fabricated by coating a long-wavelength-pass filter onto the front panel of the glass substrates of devices, similar to those shown in Example 15. The coating material in this example was a layer of PPV which was converted from its precursor film at 230° C. The photoresponses of the devices with and without the filter are shown in FIG. 13A. The visual response of the human eye, V(λ) (see FIG. 13B), and the transmittance of the PPV optical filter are shown for comparison. The photoresponse of the P3OT diode closely coincided with V(λ) for wavelengths longer than 560 nm, while the optical transmittance of the PPV filter followed V(λ) over a broad range between 450 nm and 550 nm.
- This example demonstrates a polymer photodetector with visual response essentially equivalent to V(λ), which is of great interest in optical engineering and biophysical/biomedical applications.
- Solar-blind UV detectors were fabricated with polyblend MEH-PPV:C60. ITO and Al were used as anode and cathode materials. The devices were fabricated on an UV bandpass filter purchased from Melles Griot Inc. (product No. 03 FCG 177). FIG. 14 shows the spectral response of the UV detector operating at −2V. The spectral response of the MEH-PPV:C60 photodiode on ITO/glass substrate and the response of an UV-enhanced Si photodiode are plotted for comparison. The data show that the polymer UV detector was sensitive to UV radiation between 300-400 nm with photosensitivity of ˜150 mA/W, comparable to that of UV-enhanced silicon photodiode. The data also show that the photoresponse of the MEH-PPV photodiode was suppressed (over 103 times) by the optical bandpass filter.
- This example demonstrates that high sensitivity, solar-blind UV detectors can be fabricated by integrating voltage-switchable organic photodiodes with UV pass optical filters.
- Example 14 was repeated except that the active layer was a thin PTV layer. The spectral response of a PTV photodiode is shown in FIG. 15A, which covers the range from 300 to 700 nm; i.e., spanning the entire visible range. Selected color detection was achieved by inserting a bandpass filter or a long wavelength filter in front of the detectors. FIG. 15B shows the responses of a blue-color pixel, a green-color pixel and a red-color pixel made with a panel of color filters and an array of PTV photodiodes. The transmittance of the corresponding R, G, B color filters is shown in FIG. 15C.
- This example demonstrates that by coupling the polymer image sensor with a panel of color filters, R, G, B color recognition can be achieved with a panel of polymer photodiode matrix with response covering entire visible spectrum.
- Red, green and blue (R, G, B) color detection were achieved following the approach shown in FIG. 5. The materials used for the active layers were PPV with a long wavelength cut-off at 500 nm; poly(dihexyloxy phenylene vinylene), “PDHPV”, with a long wavelength cut-off at 600 nm; and PTV with long wavelength cut-off at 700 nm. Films were cast from solutions in their precursor forms with thickness between 1000 Å-3000 Å. Conversion to the conjugated forms was carried out at temperatures between 150-230° C. The conjugated films formed in this way were insoluble to organic solvents. Thus, patterning of these materials on a single substrate in dot or strip shapes can be achieved with standard photolithography, screen printing and the like. The normalized photoresponse of these photodiodes is shown in FIG. 16A. An ITO/glass substrate was used in this experiment which is optically transparent in visible and opaque in UV.
- Red and green selective color detection were achieved by differentiation of the signals from these photodiodes (this operation can be done in the read-out circuit). The differential responses of these photodiodes are shown in FIG. 16B. Red color detection (with response between 600-700 nm) was achieved by subtracting the signal from the PTV photodiode from the signal from the PDHPV photodiode. Green color detection (with response between 500-600 nm) was achieved by subtraction of the PDHPV signal from the PPV signal. The blue color detection was obtained by PPV photodiode directly.
- This example demonstrates that R, G, B selected color detection and full-color image sensors can be achieved by patterning three photosensitive materials on a substrate with uniform optical characteristics.
- Voltage-switchable photodiodes were fabricated with the conjugated polymer poly(p-phenyl vinylene), PPV as photoactive material. The PPV films were spin-cast onto ITO substrates from a nonconjugated precursor solution and then converted to conjugated form by heating at 200-230° C. for 3 hours. Al was used as the back electrode. The active area was ˜0.15 cm2. The I-V characteristics of this photodiode in the dark and under illumination are shown in FIG. 17. The photocurrent/darkcurrent ratio is in the range of 104 for white light illumination of a few mW/cm2. Relatively low dark current was observed in forward bias as compared to that observed in photodiodes of, for example, in Example 1. This allows photodetection in both forward bias and reverse bias as shown in FIG. 17. The photosensitivity can be switched on and off by varying the external biasing voltage. For example, under white (or UV) light illumination, the photocurrent at +5V or −5V is 2000 times higher than that at +0.95V (or 0.3V).
- This example demonstrates that the photodiode can be switched on by applying a forward bias (beyond the vicinity of the voltage corresponding the off state) or a reverse bias. Photodiodes operable in both switch polarities are useful in certain circuit designs and applications.
- Voltage-switchable photodetectors were fabricated which had a heterojunction structure as their active layers, they had an ITO/donor layer/acceptor layer/metal structure. The materials used for the donor layer were MEH-PPV and PPV. The material used for the acceptor layer were C60, laid down by physical vapor deposition and PCBM and PCBCR laid down by drop casting or spin casting. A data set for a MEH-PPV/C60 photodiode is shown in FIG. 18.
- Multiple junctions were observed in these devices. A build-up potential of ˜−0.5V (forward bias was assigned as the positive bias to ITO) was seen in the I-V curve taken in dark. The other junction was revealed when the devices were illuminated. The overall effective barrier is −0.15V (changed sign). The photocurrent/darkcurrent ratio was 104 over a broad bias range. Voltage-switchable photosensitivity was seen in both forward and reverse bias. For instance, the on/off ratio of the photocurrent is ˜103 between +2V and +0.15V bias.
- This example demonstrates that voltage-switchable photodetectors can be fabricated in heterojunction form with two (or more) organic semiconductors with different electronic structures. The photosensitive mode can be achieved in both forward and reverse biases in these devices.
- Voltage-switchable photosensors was fabricated in the configuration shown in FIG. 1. Glass with patterned ITO was used as the substrate. The size of each test pixel was ˜0.1 cm2. The sensing material used was poly(3-hexyl thiophene), P3HT, which was spin cast at room temperature from a 2.5 wt % solution in toluene. Similar to the spectral response of P3OT (see Example 10), the photoresponse of P3HT sensor covers the entire visible and near UV spectral region such that red, green and blue full-color recognition can be achieved by color filtering techniques.
- FIG. 19 shows the photo- and dark currents from a P3HT device with 3150 Å film thickness. The data were taken with white light illumination of 8 mW/cm2 (between 400 nm and 700 nm) and with monochromatic light (600 nm at 1.1 mW/cm2). In the dark, the reverse current saturates at low field region and then increases with the biasing voltage, to ˜2×10−5 mA/cm2 at −25 V bias. The forward current increases exponentially under forward bias (for voltages >1 V), reaching ˜1 mA/cm2 at 3 V bias. The exponential forward current covers more than 5 orders of magnitude in the voltage range from 1-2 V. The rectification ratio at 2 V is over 104. Strong photosensitivity was observed in reverse bias. The photocurrent at −25 V reaches 5.33 mA/cm2 under 8 mW/cm2, white light illumination. This number corresponds to a photoresponsivity of in excess of 0.5 A/W, corresponding to a quantum efficiency larger than 100% electrons/photon. A high Iph(Von)/Iph(Voff) switching ratio was also achieved in this devices: under 8 mW/cm2, Iph(−25V)/Iph(0.5)is ˜4×107. This switching ratio is equal to or even better than the switching ratio of TFT-based photosensors made with inorganic semiconductors (104-107).These organic photodiodes also exhibit a high Iph(V)/Idark(V) ratio. The Iph/Idark at −25 V is ˜4×105 for 8 mW/cm2 white light illumination, which implies that more than 18 bits (2.6×105) gray levels can be resolved for image applications.
- The high switching ratio implies that for an x-y addressable 2D photodiode matrix of 400×390 pixels (refer to FIG. 3 of the 2D patent), more than 256 gray levels can be resolved. Adopting quad-matrix design (four sub-matrices arranged in each quadrants), more than 1000×625 pixels are possible with the same resolution. This pixel density is even better than the SVGA standard. The drive circuit for these photodiode matrices is simplified; digital shift registers and BCD digital decoders can be used.
- These photosensors can also be used to fabricate high pixel density linear photodiode arrays. Since only the pixel at the node contributes to the pixel dark current, there is no restriction on the number of pixels. Hence, the gray level of the sensor array can be as high as 218=3×105. These results suggest that the organic photosensor arrays constructed from ITO/P3HT/Al can be used for high quality image sensing. Moreover, the driver circuits for column selection are simplified considerably and digital shift registers or digital decoders can be used directly.
- This example demonstrates an organic photosensor with high switching ratio and high Iph/Idark ratio. The photosensitivity of such photosensors covers the entire visible spectral range. These sensors are especially suitable for constructing linear photodiode arrays and 2D photodiode matrices for high quality image sensing applications.
- Linear photodiode arrays were fabricated with 102 sensing elements, each made with P3OT as the semiconducting polymer. Two typical structures of the photodiode arrays are shown in FIG. 20A and FIG. 20B. The pixel size was ˜0.635 mm×0.635 mm. The length of the total sensing area was ˜2.5″, longer than any linear photodiode array commercially available. A full-color linear scanner was constructed with a sensing circuit shown in FIG. 21, no analog switching elements (such as field effect transistors) were used in this driver. The read out circuit was digitized into 8 bit with 256 gray levels. Red, green and blue color filters were mounted on a panel and was switched in front of the linear diode array when collecting the corresponding images. The linear photodiode array was mounted on a computer controlled translation stage for the image scanning. A full-color image taken with this scanner is shown in FIG. 22D. It was recovered by a superposition of the red, green and blue color images (FIGS.22(a, b, c)) taken separately. The image quality was similar to that achieved with a commercial color scanner in the same pixel format (40 dpi) with so-called “multi-million ( 2563) colors” format.
- Linear photodiode arrays were also fabricated in 40 dpi and 50 dpi forms with total pixels of 200 and 240. The total sensing length is close to 5″. The arrays were used for image sensing experiments. Large size (5″×11″), high quality (8-10 bit), full-color image sensing was demonstrated.
- This example demonstrates that organic photodiode arrays can be used for large size image sensing applications with full-color capability and with multiple gray levels.
- The linear photodiode arrays demonstrated in Example 22 were also used for visible-blind UV sensing. In this experiment, a visible blocking, UV pass filter was placed in front of the array. The UV image generated with UV ink was projected onto the sensor. The UV image was read out with the organic photodiode array.
- This example demonstrates that visible-blind UV sensors can be achieved with organic photosensors, and that image in UV spectral region can be detected.
- Linear photodiode arrays were fabricated in the same configuration as that of Example 22 (1×102 pixels, 40 pixels/in). One of the sensor arrays was used as an optical beam analyzer to test the optical field distribution a laser beam. The intensity distribution of the testing optical field is shown in FIG. 23. This example demonstrates that the polymer photodiode array can be used to detect spatial distribution of an optical beam. This function is of broad applications in industrial automation.
- Another 1×102 linear photodiode array was fabricated on PET substrate (7 mil in thickness). The flexible sensor array was arranged in a semicircular shape. A point light source from a green light emitting diode was placed at the center of the circle, and the angular distribution of the light intensity was tested with the curved sensor array. The result is shown in FIG. 24.
- This example demonstrates that the polymer linear photodiode arrays can be fabricated onto flexible substrates or on curved substrates to fit into an optical apparatus or to probe the spatial distribution of an optical field. The fabrication process and the thin film architecture of the polymer photodiode arrays also allow them to be integrated with electronic drivers on a silicon wafer or integrated with an adapted optical component.
- A P3OT photodiode array was used as the detector of an UV-visible spectrometer for transmission measurement. The setup is shown in FIG. 25. A transmission spectrum of a thin film of poly(p-phenylene vinylene), PPV, was measured with the polymer linear photodiode arrays. The result is shown in FIG. 26.
- This example demonstrates that the organic photodiode arrays can be used for spectrographic applications.
- Voltage-switchable photosensors were fabricated in a metal(1)/P3HT/metal(2) sandwich structure. In one case, metal(1) was Au and metal(2) was Al. The thickness of the Au layer was varied from 20 nm to 80 nm and the optical transmission of the Au layer was varied from 50% to ˜1%. The optical reflection of the Au layer varies correspondingly. The thickness of the Al layer was more than 100 nm, so that its reflectance was almost 100%. Such a metal/organic layer/metal structure forms an optical microcavity (optical etalon) device in the spectral region where the optical absorption of the organic layer is relatively low. Such a microcavity structure possesses optical resonance at selected wavelengths. The center wavelength and the bandwidth of the sensing profile can be adjusted by changing the reflection of the metal electrode, by the absorption coefficient, the dielectric constant and the thickness of the organic layer. FIG. 27 shows the spectral response of such device.
- Microcavity devices were also made in the “reverse” structure similar to that shown in FIG. 2; i.e., with light incident onto the free surface electrode (13). The devices were made in both configurations: glass/Au(100 nm)/MEH-PPV/Ag(50 nm) and glass/Ag(100 nm)/MEH-PPV/Au(50 nm). In these devices, Au acts as the anode and Ag as the cathode. Selective spectral response was observed in both structures. These results demonstrate the flexibility of fabricating the wavelength selective sensors on either transparent substrates or opaque substrates. These results also demonstrate that the devices can be designed so that the light is incident onto either the anode or cathode electrode.
- Wavelength selective photosensors were also fabricated with substrates containing an optical stack (sometimes called DBR, Defractive Bragg Reflector). The transmission of the DBR was ˜2%. The photosensors were fabricated as follows: glass/DBR/ITO/MEH-PPV:PCBM/Al. Wavelength selective spectral response was observed with ˜2 nm bandwidth.
- This example also demonstrates that the organic photosensors can be constructed with wavelength selectivity of narrow bandwidth. Building such a photodiode array or 2D matrix in which each pixel has a different sensing profile forms a flat-panel spectrometer. These kinds of devices have great potential for image sensing, spectrographic, biophysical and biomedical applications.
Claims (38)
1. A switchable organic photodetector capable of producing a photocurrent in response to light impinging thereupon comprising a photodiode and a variable voltage source,
said photodiode having a built-in potential and comprising:
a first electrode;
a photoactive organic layer disposed on said first electrode; and
a second electrode disposed on said photoactive organic layer; and
said voltage source adapted to selectively apply a switching voltage across said first electrode and said second electrode, said switching voltage imparting a photosensitivity above 1 mA/W at a preselected operating bias and near-zero photosensitivity at a cut-off bias substantially equivalent in magnitude to said built-in potential.
2. A photodiode detector of claim 1 wherein the operating bias is an operating reverse bias.
3. A photodiode detector of claim 1 wherein the operating bias is an operating forward bias.
4. A read-out circuit comprising an organic photodiode detector of claim 1 and means for detecting the photocurrent, wherein the operating bias is in the range of 1-15 V and represents an ON state of the photodiode, said detector having a photosensitivity above 1 mA/Watt in said ON state, and wherein the cut-off bias represents an OFF state of the photodiode equivalent to zero photoresponse at an output of the read-out circuit.
5. The read out circuit of claim 4 wherein the ON and OFF states provide a digital read out.
6. A photodiode array comprising a plurality of photodiode detectors of claim 1 said detectors having their photodiodes arranged in an array, each of said photodiodes being selectively addressable as a pixel of said array.
7. The photodiode array of claim 6 , wherein said array comprises at least one row of photodiodes and at least one column of photodiodes, each row having associated therewith a common anode, each column having associated therewith a common cathode, the first electrode of each photodiode of a row being connected to said common anode, the second electrode of each photodiode of a column being connected to said common cathode, said voltage source adapted to apply said switching voltage across at least one common anode and at least one common cathode to thereby selectively activate at least one pixel of said array.
8. The photodiode array of claim 7 , comprising means for applying said switching voltage across a plurality of common anodes and at least one common cathode to thereby selectively activate at least one column of pixels of said array.
9. The photodiode array of claim 7 , comprising means for applying said switching voltage across a plurality of common cathodes and at least one common anode to thereby selectively activate at least one row of pixels of said array.
10. A scannable array of voltage-switchable organic photodiodes each having a built-in potential and a predetermined photosensitivity range, said array comprising:
a support substrate;
a first electrode layer comprising at least one linear electrode disposed on said support substrate along a first direction;
a photoactive organic layer disposed on said linear electrode;
a second electrode layer comprising a plurality of linear electrodes disposed on said photoactive layer along a second direction transverse to said first direction; and
a voltage source adapted to apply a switching voltage across at least one electrode of said first electrode layer and at least one electrode of said second electrode layer, said switching voltage thereby imparting to at least one selected photodiode a photosensitivity above 1 mA/W at an operating reverse bias and near-zero photosensitivity at a cut-off bias substantially equivalent in magnitude to said built-in potential.
11. A method of selectively detecting light incident on an array of voltage-switchable organic photodiode detectors, said array comprising a plurality of photodiodes arranged in a row and column matrix, each photodiode having a built in potential and adapted to generate an output in response to incident radiation, each photodiode comprising a first electrode, a photoactive organic layer disposed on said first electrode, and a second electrode disposed on said photoactive layer, the first electrode of each photodiode in a row being electrically connected to a common anode, the second electrode of each photodiode in a column being electrically connected to a common cathode, said method comprising:
sequentially activating a selected column of photodiodes by;
applying an operating bias voltage across the common cathode associated with said selected column and all the common anodes, said operating bias voltage imparting to each photodiode of the selected column a photosensitivity above 1 mA/W;
applying a cut-off voltage across remaining cathodes and all the anodes, said cut-off voltage being equivalent in magnitude to said built-in potential and imparting to the photodiodes of all columns other than the selected column near-zero photosensitivity; and
sequentially reading out the generated output of the selected column of photodiodes.
12. A method of selectively detecting light incident on an array of voltage-switchable organic photodiode detectors, said array comprising a plurality of photodiodes arranged in a row and column matrix, each photodiode having a built in potential and adapted to generate an output in response to incident radiation, each photodiode comprising a first electrode, a photoactive organic layer disposed on said first electrode, and a second electrode disposed on said photoactive layer, the first electrode of each photodiode in a row being electrically connected to a common anode, the second electrode of each photodiode in a column being electrically connected to a common cathode, said method comprising:
sequentially activating a selected row of photodiodes by;
applying an operating bias voltage across the common anode associated with said selected row and all the common cathodes, said operating bias voltage imparting to each photodiode of the selected row a photosensitivity above 1 mA/W;
applying a cut-off voltage across remaining anodes and all the cathodes, said cut-off voltage being equivalent in magnitude to said built-in potential and imparting to the photodiodes of all rows other than the selected row near-zero photosensitivity; and
sequentially reading out the generated output of the selected row of photodiodes.
13. An organic photodiode detector comprising a photodiode and a voltage source, said photodiode having a built-in potential and a prescribed photosensitivity range in response to incident radiation, said photodiode comprising:
a first electrode;
a photoactive organic layer disposed on said first electrode;
a second electrode disposed on said photoactive organic layer; and
said voltage source adapted to apply an operating biasing voltage across said first electrode and said second electrode, said biasing voltage operating to vary said prescribed photosensitivity range.
14. The organic photodiode detector of claim 13 , wherein the photosensitivity of said photodiode is above 1 mA/W at an operating bias of said voltage source and is at a near-zero level at a cut-off bias substantially equivalent in magnitude to said built-in potential, said voltage source being switchable between said operating bias and said cut-off bias.
15. The organic photodiode detector of claim 13 , additionally comprising a support substrate upon which the first electrode is disposed wherein said support substrate and said first electrode are substantially transparent to the incident radiation.
16. The organic photodiode detector of claim 13 , wherein said photoactive organic layer is comprised of a semiconducting conjugated polymer.
17. The organic photodiode detector of claim 16 , wherein said semiconducting conjugated polymer is selected from:
poly(phenylenevinylene), and its derivatives;
polythiophene, and its derivatives;
poly(thiophene vinylene), and its derivatives;
polyacetylene, and its derivatives;
polyisothianaphene, and its derivatives;
polypyrrole, and its derivative;
poly(2,5-thienylenevinylene), and its derivatives;
poly(p-phenylene), and its derivatives;
polyflourene, and its derivatives;
polycarbazole, and its derivatives;
poly(1,6-heptadiyne), and its derivatives;
polyquinolene, and its derivatives; and
polyaniline, and its derivatives.
18. The organic photodiode detector of claim 16 , wherein said semiconducting conjugated polymer is the donor of a donor/acceptor polyblend, said acceptor being selected from poly(cyanophenylene vinylene), fullerene molecules including C60 and functional derivates thereof, PCBM and PCBCR.
19. The organic photodiode detector of claim 16 wherein said semiconducting conjugated polymer is the donor of a donor/acceptor polyblend, said acceptor being selected from an organic photoreceptor molecule or an electron transport molecule.
20. The organic photodiode detector of claim 13 , wherein said photoactive organic layer comprises a material selected from a polymer/polymer polyblend, a polymer/(organic molecule) polyblend, and organic molecules, organometallic molecules, oligomers or molecular blends selected from:
anthracene and its derivatives,
tetracene and its derivatives,
phthalocyanine and its derivatives,
pinacyanol and its derivatives,
fullerene C60 and its derivatives,
thiophene and its derivatives,
phenylene and its derivatives,
oxadiazole and its derivatives,
PBD and its derivatives,
Alq3 and other metal-chelate (M-L3) type organometallic molecules,
6T/C60 and blends comprising their derivatives,
6T/pinacyanol and blends comprising their derivatives,
phthalocyanine/o-chloranil and blends comprising their derivatives,
anthracene/C60 and blends comprising their derivatives, and
anthracene/o-chloranil and blends comprising their derivatives.
21. The organic photodiode detector of claim 13 , wherein said photoactive organic layer is arranged in a semiconducting heterojunction structure having at least one set of donor and acceptor regions disposed therein.
22. The organic photodiode detector of claim 13 , wherein said photoactive organic layer comprises optically inert organic additives and/or optically inert inorganic nanoparticles.
23. The organic photodiode detector of claim 13 , wherein at least one of said first and second electrodes comprises conducting polymer.
24. The organic photodiode detector of claim 13 , additionally comprising an optical filter layer adapted to restrict transmission of incident radiation to a predetermined wavelength range.
25. The organic photodiode detector of claim 24 , wherein the predetermined wavelength range is selected to permit a spectral response which follows that of the human eye.
26. A photodiode array comprising a pluraty of photodiode detectors of claim 13 , said detectors having thereon photodiode arranged in an array, each of said photodiodes being selectively addressable as a pixel of said array which said pixels including pixels for detecting radiation in the red range, pixels for detecting radiation in the green range, and pixels for detecting radiation in the blue range.
27. The organic photodiode detector of claim 13 , additionally comprising a scintillating over layer, said scintillation over layer emitting photons in response to incident high energy ionized particles, said photons being detected by the organic photodetector.
28. The organic photodiode detector of claim 27 , wherein said ionized particles are selected from high energy photons, electrons, characteristic of X-rays, beta particles and gamma radiation.
29. The organic photodiode detector of claim 13 , additionally comprising an organic sensing layer that generates mobile electrons and holes in response to incident high energy ionized particles.
30. The scannable array of claim 10 , wherein the support substrate is made of insulating or semiconducting material and embedded with integrated driving and readout circuits.
31. The scannable array of claim 30 , wherein the integrated driving circuit comprises a column or row selection circuit.
32. The scannable array of claim 30 , wherein the readout circuit comprises current integrators or current-voltage converters.
33. The photodiode array of claim 7 , additionally comprising a coating of black matrix in the space between the pixels.
34. The organic photodetector of claim 13 , additionally comprising an optical mirror placed to form a microcavity optical etalon device which possesses selective response at resonant wavelengths.
35. The organic photodetector of claim 13 , additionally comprising two optical mirrors placed outside to form a microcavity device (optical etalon) which possesses selective response at resonant wavelengths.
36. The organic photodetector of claim 13 , wherein a buffer layer is inserted between an electrode and the photoactive organic layer.
37. The organic photodetector arrays of claim 7 , wherein the switching voltage varies among pixels so that inhomogeneity of photosensitivity can be compensated with external bias.
38. The organic photodetector array of claim 7 , wherein the switching voltage varies among pixels following a defined pattern so that a sensing array with designed photosensitivity pattern is achieved for specific applications such as image procession.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/930,771 US20020017612A1 (en) | 1998-02-02 | 2001-08-16 | Organic diodes with switchable photosensitivity useful in photodetectors |
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US7334698P | 1998-02-02 | 1998-02-02 | |
US09/241,660 US6303943B1 (en) | 1998-02-02 | 1999-02-02 | Organic diodes with switchable photosensitivity useful in photodetectors |
US09/930,771 US20020017612A1 (en) | 1998-02-02 | 2001-08-16 | Organic diodes with switchable photosensitivity useful in photodetectors |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/241,660 Division US6303943B1 (en) | 1998-02-02 | 1999-02-02 | Organic diodes with switchable photosensitivity useful in photodetectors |
Publications (1)
Publication Number | Publication Date |
---|---|
US20020017612A1 true US20020017612A1 (en) | 2002-02-14 |
Family
ID=22113190
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/241,660 Expired - Lifetime US6303943B1 (en) | 1998-02-02 | 1999-02-02 | Organic diodes with switchable photosensitivity useful in photodetectors |
US09/930,771 Abandoned US20020017612A1 (en) | 1998-02-02 | 2001-08-16 | Organic diodes with switchable photosensitivity useful in photodetectors |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/241,660 Expired - Lifetime US6303943B1 (en) | 1998-02-02 | 1999-02-02 | Organic diodes with switchable photosensitivity useful in photodetectors |
Country Status (8)
Country | Link |
---|---|
US (2) | US6303943B1 (en) |
EP (1) | EP1055260A1 (en) |
JP (1) | JP2002502129A (en) |
KR (1) | KR20010040510A (en) |
CN (1) | CN1295721A (en) |
AU (1) | AU2492599A (en) |
CA (1) | CA2319536A1 (en) |
WO (1) | WO1999039395A1 (en) |
Cited By (65)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1376663A2 (en) * | 2002-06-28 | 2004-01-02 | Hewlett-Packard Development Company, L.P. | Method and system for forming a semiconductor device |
WO2004017429A1 (en) * | 2002-08-15 | 2004-02-26 | Detection Technology Oy | Packaging structure for imaging detectors |
US20040113085A1 (en) * | 2002-09-23 | 2004-06-17 | Bjoern Heismann | Image detector for X-ray radiation |
US20040159793A1 (en) * | 2003-02-19 | 2004-08-19 | Christoph Brabec | Carbon-based photodiode detector for nuclear medicine |
US20040262614A1 (en) * | 2003-06-27 | 2004-12-30 | Michael Hack | Grey scale bistable display |
US20050040390A1 (en) * | 2002-02-20 | 2005-02-24 | Martin Pfeiffer | Doped organic semiconductor material and method for production thereof |
US20050195318A1 (en) * | 2003-02-07 | 2005-09-08 | Takahiro Komatsu | Organic information reading unit and information reading device using the same |
WO2006010618A1 (en) * | 2004-07-28 | 2006-02-02 | Quantum Semiconductor Llc | Photonic devices monolithically integrated with cmos |
US20060044451A1 (en) * | 2004-08-30 | 2006-03-02 | Eastman Kodak Company | Wide angle lenslet camera |
US20060067472A1 (en) * | 2004-09-30 | 2006-03-30 | Possin George E | Method and apparatus for measuring X-ray energy |
US20060138447A1 (en) * | 2003-06-17 | 2006-06-29 | Nederlandse Organisatie Voor Toegepast- Natuurwetenschappelijk Onderzoek Tno | Light emitting diode |
US20060186400A1 (en) * | 2005-02-10 | 2006-08-24 | Japan Science And Technology Agency | Organic photodiode and method for manufacturing the organic photodiode |
WO2006134114A1 (en) * | 2005-06-17 | 2006-12-21 | Siemens Aktiengesellschaft | Organic pixilated flat panel detector and method for the production thereof |
US20070096275A1 (en) * | 2005-08-10 | 2007-05-03 | Jiahn-Chang Wu | Supporting frame for surface-mount diode package |
US20070108890A1 (en) * | 2005-11-15 | 2007-05-17 | Stephen Forrest | Organic electric camera |
US20070116179A1 (en) * | 2005-11-24 | 2007-05-24 | Martin Spahn | Flat image detector |
US20080135809A1 (en) * | 2002-09-24 | 2008-06-12 | Che-Hsiung Hsu | Electrically conducting organic polymer/nanoparticle composites and method for use thereof |
US20080142721A1 (en) * | 2004-06-01 | 2008-06-19 | Siemens Aktiengesellschaft | X-Ray Detector |
US20080237770A1 (en) * | 2007-03-30 | 2008-10-02 | Fujifilm Corporation | Radiation detector |
US20080248314A1 (en) * | 2003-04-22 | 2008-10-09 | Che-Hsiung Hsu | Water dispersible polythiophenes made with polymeric acid colloids |
US20080277650A1 (en) * | 2007-05-07 | 2008-11-13 | Chunghwa Picture Tubes, Ltd. | Organic photodetector and fabricating method of organic photodetector and organic thin film transistor |
US20080296536A1 (en) * | 2002-09-24 | 2008-12-04 | Che-Hsiung Hsu | Water dispersible polythiophenes made with polymeric acid colloids |
US20090072201A1 (en) * | 2002-09-24 | 2009-03-19 | E. I. Du Pont De Nemours And Company | Water dispersible polyanilines made with polymeric acid colloids for electronics applications |
US20090108791A1 (en) * | 2007-10-31 | 2009-04-30 | Eiji Isobe | Motor control apparatus |
US20090114884A1 (en) * | 2007-05-18 | 2009-05-07 | Che-Hsiung Hsu | Aqueous dispersions of electrically conducting polymers containing high boiling solvent and additives |
US20090205698A1 (en) * | 2008-02-14 | 2009-08-20 | Mrinal Thakur | Photovoltaic applications of non-conjugated conductive polymers |
US20100032551A1 (en) * | 2007-03-01 | 2010-02-11 | Koninklijke Philips Electronics N.V. | Optical detector device |
US20100294936A1 (en) * | 2007-09-13 | 2010-11-25 | Boeberl Michaela | Organic photodetector for the detection of infrared radiation, method for the production thereof, and use thereof |
US20110068426A1 (en) * | 2009-09-22 | 2011-03-24 | Intersil Americas Inc. | Photodiodes and methods for fabricating photodiodes |
US20110155966A1 (en) * | 2002-09-24 | 2011-06-30 | E.I. Du Pont De Nemours And Company | Electrically conducting organic polymer/nanoparticle composites and methods for use thereof |
US20110168952A1 (en) * | 2006-12-29 | 2011-07-14 | E. I. Du Pont De Nemours And Company | High work-function and high conductivity compositions of electrically conducting polymers |
US20110228144A1 (en) * | 2010-03-19 | 2011-09-22 | Hui Tian | Dark current reduction in image sensors via dynamic electrical biasing |
US20120090685A1 (en) * | 2010-10-15 | 2012-04-19 | Forrest Stephen R | Materials for controlling the epitaxial growth of photoactive layers in photovoltaic devices |
US20120146006A1 (en) * | 2009-05-20 | 2012-06-14 | David Hartmann | Material for a hole transport layer with p-dopant |
WO2012080927A2 (en) | 2010-12-13 | 2012-06-21 | Koninklijke Philips Electronics N.V. | Radiation detector with photodetectors |
DE102010055633A1 (en) * | 2010-12-22 | 2012-06-28 | MAX-PLANCK-Gesellschaft zur Förderung der Wissenschaften e.V. | Semiconductor detector with offset bonding contact |
US8409476B2 (en) | 2005-06-28 | 2013-04-02 | E I Du Pont De Nemours And Company | High work function transparent conductors |
US20140098065A1 (en) * | 2012-10-04 | 2014-04-10 | Corning Incorporated | Touch screen systems and methods for sensing touch screen displacement |
USRE44853E1 (en) | 2005-06-28 | 2014-04-22 | E I Du Pont De Nemours And Company | Buffer compositions |
US8723027B2 (en) | 2008-02-14 | 2014-05-13 | Mrinal Thakur | Photovoltaic applications of non-conjugated conductive polymers |
US8760494B1 (en) * | 2010-05-04 | 2014-06-24 | Lockheed Martin Corporation | UV detection of objects hidden in foliage |
US8765022B2 (en) | 2004-03-17 | 2014-07-01 | E I Du Pont De Nemours And Company | Water dispersible polypyrroles made with polymeric acid colloids for electronics applications |
US8779542B2 (en) | 2012-11-21 | 2014-07-15 | Intersil Americas LLC | Photodetectors useful as ambient light sensors and methods for use in manufacturing the same |
US8845933B2 (en) | 2009-04-21 | 2014-09-30 | E I Du Pont De Nemours And Company | Electrically conductive polymer compositions and films made therefrom |
US20140295571A1 (en) * | 2008-12-18 | 2014-10-02 | Bayer Healthcare Llc | Method and assembly for determining the temperature of a test sensor |
US8945427B2 (en) | 2009-04-24 | 2015-02-03 | E I Du Pont De Nemours And Company | Electrically conductive polymer compositions and films made therefrom |
US8945426B2 (en) | 2009-03-12 | 2015-02-03 | E I Du Pont De Nemours And Company | Electrically conductive polymer compositions for coating applications |
CN104641206A (en) * | 2012-07-18 | 2015-05-20 | 美高森美公司 | Solid-state photodetector with variable spectral response |
WO2016055047A1 (en) * | 2014-10-07 | 2016-04-14 | Technische Universität Dresden | Apparatus for spectrometrically capturing light with a photodiode which is monolithically integrated in the layer structure of a wavelength-selective filter |
EP2513995B1 (en) * | 2009-12-16 | 2016-05-11 | Heliatek GmbH | Photoactive component having organic layers |
US9496512B2 (en) | 2011-06-22 | 2016-11-15 | Siemens Aktiengesellschaft | Weak light detection using an organic, photosensitive component |
US9685600B2 (en) | 2015-02-18 | 2017-06-20 | Savannah River Nuclear Solutions, Llc | Enhanced superconductivity of fullerenes |
US20180075191A1 (en) * | 2014-03-06 | 2018-03-15 | Ricoh Company, Ltd. | Film to dicom conversion |
US20180159058A1 (en) * | 2016-12-05 | 2018-06-07 | Commissariat à l'énergie atomique et aux énergies alternatives | Infrared photodetector |
US10104322B2 (en) | 2014-07-31 | 2018-10-16 | Invisage Technologies, Inc. | Image sensors with noise reduction |
US10425601B1 (en) | 2017-05-05 | 2019-09-24 | Invisage Technologies, Inc. | Three-transistor active reset pixel |
US10789467B1 (en) | 2018-05-30 | 2020-09-29 | Lockheed Martin Corporation | Polarization-based disturbed earth identification |
US10976844B2 (en) * | 2017-09-27 | 2021-04-13 | Dongwoo Fine-Chem. Co, Ltd. | Touch sensor and manufacturing method thereof |
WO2021108678A1 (en) * | 2019-11-27 | 2021-06-03 | The Regents Of The University Of California | Uncooled infrared photodetectors |
US11069869B2 (en) * | 2017-10-23 | 2021-07-20 | Sumitomo Chemical Company, Limited | Photoelectric conversion element and method for producing the same |
US20210364430A1 (en) * | 2020-05-20 | 2021-11-25 | Ysi, Inc. | Extended solid angle turbidity sensor |
US20210375996A1 (en) * | 2018-01-15 | 2021-12-02 | Xarpotech UG (Haftungsbeschraenkt) | Organic photoreceptors |
US11204508B2 (en) | 2017-01-19 | 2021-12-21 | Lockheed Martin Corporation | Multiple band multiple polarizer optical device |
EP3600525B1 (en) * | 2017-03-31 | 2022-08-03 | École Polytechnique Fédérale de Lausanne (EPFL) | Polymer-based optoelectronic interface and methods for its manufacture |
US11550407B2 (en) | 2019-01-18 | 2023-01-10 | Semiconductor Energy Laboratory Co., Ltd. | Display system, display device, and light-emitting apparatus |
Families Citing this family (107)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0917208A1 (en) * | 1997-11-11 | 1999-05-19 | Universiteit van Utrecht | Polymer-nanocrystal photo device and method for making the same |
GB9808016D0 (en) * | 1998-04-15 | 1998-06-17 | Cambridge Display Tech Ltd | Display control |
US7256766B2 (en) * | 1998-08-27 | 2007-08-14 | E Ink Corporation | Electrophoretic display comprising optical biasing element |
GB9907931D0 (en) * | 1999-04-07 | 1999-06-02 | Univ Edinburgh | An optoelectronic display |
US7030412B1 (en) * | 1999-05-05 | 2006-04-18 | E Ink Corporation | Minimally-patterned semiconductor devices for display applications |
US6815218B1 (en) * | 1999-06-09 | 2004-11-09 | Massachusetts Institute Of Technology | Methods for manufacturing bioelectronic devices |
FR2799003B1 (en) | 1999-09-23 | 2002-04-19 | Commissariat Energie Atomique | RADIATION DETECTOR USING COMPOSITE MATERIAL AND METHOD FOR MANUFACTURING THE SAME |
DE19961673A1 (en) * | 1999-12-21 | 2001-06-28 | Philips Corp Intellectual Pty | Flat x-ray detector with alkali halide scintillator |
AT411306B (en) | 2000-04-27 | 2003-11-25 | Qsel Quantum Solar Energy Linz | PHOTOVOLTAIC CELL WITH A PHOTOACTIVE LAYER OF TWO MOLECULAR ORGANIC COMPONENTS |
US20020031602A1 (en) * | 2000-06-20 | 2002-03-14 | Chi Zhang | Thermal treatment of solution-processed organic electroactive layer in organic electronic device |
WO2002027811A1 (en) * | 2000-09-28 | 2002-04-04 | Siemens Aktiengesellschaft | Image sensor with a cell structure of organic semiconductors |
AU2001297881A1 (en) * | 2000-11-01 | 2003-01-02 | James J. Myrick | Nanoelectronic interconnection and addressing |
EP1209708B1 (en) * | 2000-11-24 | 2007-01-17 | Sony Deutschland GmbH | Hybrid solar cells with thermal deposited semiconductive oxide layer |
DE10061299A1 (en) * | 2000-12-08 | 2002-06-27 | Siemens Ag | Device for determining and / or forwarding at least one environmental influence, production method and use thereof |
US6992322B2 (en) * | 2001-01-02 | 2006-01-31 | Kavassery Sureswaran Narayan | Photo-responsive organic field effect transistor |
DE10132699A1 (en) * | 2001-07-05 | 2003-01-16 | Philips Corp Intellectual Pty | Organic electroluminescent display device with optical filter |
DE10135640A1 (en) * | 2001-07-21 | 2003-02-06 | Covion Organic Semiconductors | Organic semiconductor solution used for organic integrated switches, organic field effect transistors, organic thin film transistors, organic solar cells and organic laser diodes contains one or more additives |
DE10136756C2 (en) * | 2001-07-27 | 2003-07-31 | Siemens Ag | X-ray diagnostic device with a flexible solid-state X-ray detector |
JP3682584B2 (en) * | 2001-08-06 | 2005-08-10 | ソニー株式会社 | Method for mounting light emitting element and method for manufacturing image display device |
US6569697B2 (en) * | 2001-08-20 | 2003-05-27 | Universal Display Corporation | Method of fabricating electrodes |
DE10140991C2 (en) | 2001-08-21 | 2003-08-21 | Osram Opto Semiconductors Gmbh | Organic light-emitting diode with energy supply, manufacturing process therefor and applications |
DE10142531A1 (en) * | 2001-08-30 | 2003-03-20 | Philips Corp Intellectual Pty | Sensor arrangement of light and / or X-ray sensitive sensors |
US6724511B2 (en) | 2001-11-16 | 2004-04-20 | Thin Film Electronics Asa | Matrix-addressable optoelectronic apparatus and electrode means in the same |
US7085033B2 (en) | 2001-11-30 | 2006-08-01 | Siemens Aktiengesellschaft | Electrochromic color system |
US20030121976A1 (en) * | 2002-01-03 | 2003-07-03 | Nokia Corporation | Organic light sensors for use in a mobile communication device |
ITMI20020231A1 (en) * | 2002-02-08 | 2003-08-08 | Milano Politecnico | ORGANIC SEMICONDUCTOR PHOTORETER |
JP4126019B2 (en) * | 2002-03-07 | 2008-07-30 | 新日本石油株式会社 | Photoelectric conversion element |
KR100483314B1 (en) * | 2002-03-23 | 2005-04-15 | 학교법인 인제학원 | Digital x-ray image detector |
JP2003282934A (en) * | 2002-03-25 | 2003-10-03 | Japan Science & Technology Corp | Rapid response photoelectric current multiplying device formed of mixed thin film of heterologous organic semiconductor |
DE10244177A1 (en) | 2002-09-23 | 2004-04-08 | Siemens Ag | Photosensitive screen for taking X-ray pictures has top fluorescent layer on contact layer on top of photosensor array with individual contacts on substrate with further contacts to circuit elements |
DE10314166A1 (en) * | 2003-03-28 | 2004-10-14 | Siemens Ag | Screensaver for organic displays |
JP4192236B2 (en) * | 2003-05-02 | 2008-12-10 | 独立行政法人産業技術総合研究所 | Solar cell |
KR20060034239A (en) * | 2003-06-26 | 2006-04-21 | 이 아이 듀폰 디 네모아 앤드 캄파니 | Methods for forming patterns of a filled dielectric material on substrates |
DE10330595A1 (en) * | 2003-07-07 | 2005-02-17 | Siemens Ag | X-ray detector and method for producing X-ray images with spectral resolution |
US6953705B2 (en) * | 2003-07-22 | 2005-10-11 | E. I. Du Pont De Nemours And Company | Process for removing an organic layer during fabrication of an organic electronic device |
DE10334818A1 (en) * | 2003-07-30 | 2005-03-03 | Siemens Ag | X-ray detector |
US6960917B2 (en) | 2003-11-06 | 2005-11-01 | Agilent Technologies, Inc. | Methods and apparatus for diagnosing defect locations in electrical paths of connectors of circuit assemblies |
US20080315185A1 (en) * | 2004-03-22 | 2008-12-25 | Yasushi Araki | Photodetector |
US7180238B2 (en) * | 2004-04-08 | 2007-02-20 | Eastman Kodak Company | Oled microcavity subpixels and color filter elements |
WO2005101530A1 (en) * | 2004-04-19 | 2005-10-27 | Edward Sargent | Optically-regulated optical emission using colloidal quantum dot nanocrystals |
GB0413398D0 (en) | 2004-06-16 | 2004-07-21 | Koninkl Philips Electronics Nv | Electronic device |
US8076646B2 (en) * | 2004-06-28 | 2011-12-13 | Siemens Medical Solutions Usa, Inc. | Burst-mode readout for solid state radiation detectors using partitioned pipeline architecture |
AT500855B1 (en) * | 2004-09-08 | 2006-04-15 | Bioident Biometric Technologie | DEVICE FOR EVALUATING BIOCHEMICAL SAMPLES |
US20060048811A1 (en) * | 2004-09-09 | 2006-03-09 | Krut Dimitri D | Multijunction laser power converter |
WO2006078427A2 (en) * | 2004-12-30 | 2006-07-27 | E.I. Dupont De Nemours And Company | Device patterning using irradiation |
JP4161374B2 (en) * | 2005-02-25 | 2008-10-08 | セイコーエプソン株式会社 | Electro-optical device and electronic apparatus |
US20060211272A1 (en) * | 2005-03-17 | 2006-09-21 | The Regents Of The University Of California | Architecture for high efficiency polymer photovoltaic cells using an optical spacer |
US7893429B2 (en) * | 2005-03-25 | 2011-02-22 | National University Corporation University Of Toyama | Multifunction organic diode and matrix panel thereof |
CN2788876Y (en) * | 2005-05-10 | 2006-06-21 | 张逸夫 | Artificial toy flower capable of simulating blooming movement |
US20090107539A1 (en) * | 2005-08-02 | 2009-04-30 | Adeka Corporation | Photoelectric device |
JP4905762B2 (en) * | 2005-08-23 | 2012-03-28 | 富士フイルム株式会社 | Photoelectric conversion element, imaging element, and method for manufacturing the photoelectric conversion element |
US20070045642A1 (en) * | 2005-08-25 | 2007-03-01 | Micron Technology, Inc. | Solid-state imager and formation method using anti-reflective film for optical crosstalk reduction |
US7745724B2 (en) * | 2005-09-01 | 2010-06-29 | Konarka Technologies, Inc. | Photovoltaic cells integrated with bypass diode |
JP4914597B2 (en) * | 2005-10-31 | 2012-04-11 | 富士フイルム株式会社 | Photoelectric conversion element, imaging element, and method of applying electric field to them |
EP1974391A4 (en) * | 2006-01-04 | 2010-11-17 | Univ California | Passivating layer for photovoltaic cells |
EP1830177A1 (en) * | 2006-03-02 | 2007-09-05 | F. Hoffman-la Roche AG | Integrated test element |
JP5196813B2 (en) * | 2006-03-20 | 2013-05-15 | キヤノン株式会社 | Field effect transistor using amorphous oxide film as gate insulating layer |
US20070254996A1 (en) * | 2006-04-28 | 2007-11-01 | Krzysztof Nauka | Nanocrystal-polymer composite materials and methods of attaching nanocrystals to polymer molecules |
DE102006025469A1 (en) * | 2006-05-30 | 2007-12-06 | Siemens Ag | photocell |
KR100897881B1 (en) * | 2006-06-02 | 2009-05-18 | 삼성전자주식회사 | Memory of fabricating organic memory device employing stack of organic material layer and buckminster fullerene layer as a data storage element |
DE102006038579A1 (en) * | 2006-08-17 | 2008-02-21 | Siemens Ag | Light spectral portion`s light intensity determining device e.g. optical multi-channel analyzer, has structured organic photoactive semiconductor layer arranged between anode and cathode |
DE102006038580A1 (en) * | 2006-08-17 | 2008-02-21 | Siemens Ag | Light source examining method, involves producing laminar light distribution with light source, where image dataset assigned to image of laminar light distribution, comprising pixel laminar photo detector, is produced |
US20090126779A1 (en) * | 2006-09-14 | 2009-05-21 | The Regents Of The University Of California | Photovoltaic devices in tandem architecture |
US8153029B2 (en) * | 2006-12-28 | 2012-04-10 | E.I. Du Pont De Nemours And Company | Laser (230NM) ablatable compositions of electrically conducting polymers made with a perfluoropolymeric acid applications thereof |
US8062553B2 (en) * | 2006-12-28 | 2011-11-22 | E. I. Du Pont De Nemours And Company | Compositions of polyaniline made with perfuoropolymeric acid which are heat-enhanced and electronic devices made therewith |
US7847364B2 (en) * | 2007-07-02 | 2010-12-07 | Alcatel-Lucent Usa Inc. | Flexible photo-detectors |
AT505688A1 (en) * | 2007-09-13 | 2009-03-15 | Nanoident Technologies Ag | SENSOR MATRIX FROM SEMICONDUCTOR COMPONENTS |
WO2009117613A1 (en) * | 2008-03-19 | 2009-09-24 | The Regents Of The University Of Michigan | Organic thin films for infrared detection |
KR101435517B1 (en) * | 2008-05-28 | 2014-08-29 | 삼성전자주식회사 | Image sensor using photo-detecting molecule and method of operating the same |
DE102008049702A1 (en) | 2008-09-30 | 2010-04-08 | Siemens Aktiengesellschaft | Measuring device for measuring radiation dose, organic photo detector and scintillator and for contamination control as person dosimeter or for welding seam control, has electrode arranged on substrate of photo detector |
US20100191383A1 (en) * | 2009-01-28 | 2010-07-29 | Intersil Americas, Inc. | Connection systems and methods for solar cells |
US8558103B2 (en) | 2009-01-28 | 2013-10-15 | Intersil Americas Inc. | Switchable solar cell devices |
KR101712221B1 (en) | 2009-05-14 | 2017-03-03 | 4233999 캐나다 인크. | System for and method of providing high resoution images using monolithic arrays of light emitting diodes |
CN102375417B (en) * | 2010-08-20 | 2014-03-26 | 鸿富锦精密工业(深圳)有限公司 | Optical filter switching component control circuit |
JP2013084919A (en) * | 2011-09-30 | 2013-05-09 | Sumitomo Chemical Co Ltd | Photoelectric conversion device |
DE102012200549B3 (en) | 2012-01-16 | 2013-04-18 | Siemens Aktiengesellschaft | Method for conversion of X-rays with directly changing semiconductor layer, involves adjusting intensity profile of infrared radiation so that intensity of radiation is decreased from surface over thickness of semiconductor layer |
KR101989907B1 (en) * | 2012-05-31 | 2019-06-17 | 삼성전자주식회사 | Organic image sensor and Fabrication method thereof |
JP6135109B2 (en) * | 2012-12-07 | 2017-05-31 | ソニー株式会社 | Solid-state imaging device, manufacturing method of solid-state imaging device, and electronic apparatus |
JP2014127545A (en) * | 2012-12-26 | 2014-07-07 | Sony Corp | Solid-state imaging element and solid-state imaging device including the same |
US9935152B2 (en) | 2012-12-27 | 2018-04-03 | General Electric Company | X-ray detector having improved noise performance |
AU2014280334B2 (en) * | 2013-06-13 | 2018-02-01 | Basf Se | Optical detector and method for manufacturing the same |
KR20150010811A (en) * | 2013-07-18 | 2015-01-29 | 에스케이하이닉스 주식회사 | CMOS image sensor having optical block area |
US9917133B2 (en) | 2013-12-12 | 2018-03-13 | General Electric Company | Optoelectronic device with flexible substrate |
US9257480B2 (en) | 2013-12-30 | 2016-02-09 | General Electric Company | Method of manufacturing photodiode detectors |
EP3117204B1 (en) | 2014-03-13 | 2021-06-16 | General Electric Company | Curved digital x-ray detector for weld inspection |
US9885605B2 (en) * | 2014-05-19 | 2018-02-06 | Infineon Technologies Ag | Photocell devices, systems and methods |
JP6721980B2 (en) * | 2014-12-19 | 2020-07-15 | 三星電子株式会社Samsung Electronics Co.,Ltd. | Organic photoelectric device, image sensor, and electronic device including the same |
JP6566749B2 (en) | 2015-07-01 | 2019-08-28 | 株式会社ソニー・インタラクティブエンタテインメント | Image sensor, image sensor, and information processing apparatus |
JP6914001B2 (en) | 2015-08-12 | 2021-08-04 | 株式会社ソニー・インタラクティブエンタテインメント | Image sensor, image sensor, image pickup device, and information processing device |
US9929216B2 (en) | 2015-11-24 | 2018-03-27 | General Electric Company | Processes for fabricating organic X-ray detectors, related organic X-ray detectors and systems |
EP3190619A1 (en) * | 2016-01-07 | 2017-07-12 | Nokia Technologies Oy | A photodetector apparatus and associated methods |
JP7102114B2 (en) * | 2016-11-11 | 2022-07-19 | キヤノン株式会社 | Photoelectric conversion element, image sensor and image sensor |
CN108389875A (en) | 2017-02-03 | 2018-08-10 | 松下知识产权经营株式会社 | Photographic device |
CN108389870A (en) | 2017-02-03 | 2018-08-10 | 松下知识产权经营株式会社 | Photographic device |
KR101854328B1 (en) * | 2017-02-28 | 2018-06-14 | 광운대학교 산학협력단 | Linear variable color filter based on a tapered etalon and method of manufacturing thereof |
JP6666291B2 (en) | 2017-03-21 | 2020-03-13 | 株式会社東芝 | Radiation detector |
JP6796039B2 (en) * | 2017-05-01 | 2020-12-02 | 采▲ぎょく▼科技股▲ふん▼有限公司VisEra Technologies Company Limited | Image sensor |
CN107833820A (en) * | 2017-11-30 | 2018-03-23 | 中国工程物理研究院激光聚变研究中心 | A kind of new single channel x-ray diode detection system |
GB2572741A (en) * | 2018-02-14 | 2019-10-16 | Flexenable Ltd | Pixelated sensor devices with organic photoactive layer |
US10644044B2 (en) | 2018-05-31 | 2020-05-05 | National Research Council Of Canada | Methods of manufacturing printable photodetector array panels |
KR20200055361A (en) * | 2018-11-13 | 2020-05-21 | 삼성전자주식회사 | Organic device and image sensor |
CN113454795A (en) * | 2019-01-16 | 2021-09-28 | 密歇根大学董事会 | Photodetector with semiconductor active layer for fingerprint and gesture sensor under display |
US11852756B2 (en) * | 2019-12-19 | 2023-12-26 | Carestream Health, Inc. | Radiographic detector readout |
CN111312857B (en) * | 2020-02-28 | 2023-07-18 | 上海大学 | Method for reducing dark current of perovskite detector by using organic polymer material |
CN113310576B (en) * | 2021-06-17 | 2022-06-21 | 桂林电子科技大学 | High-integration spectrum detection system based on semiconductor photodiode |
CN114530557B (en) * | 2022-01-26 | 2023-02-14 | 华南理工大学 | Method for preparing organic photosensitive diode based on copper-clad plate and application |
CN116779463B (en) * | 2023-07-13 | 2023-12-12 | 江苏富坤光电科技有限公司 | Optical semiconductor device and preparation method thereof |
Family Cites Families (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS59229863A (en) | 1983-06-13 | 1984-12-24 | Oki Electric Ind Co Ltd | Manufacture of color sensor |
FR2627922B1 (en) | 1988-02-26 | 1990-06-22 | Thomson Csf | PHOTOSENSITIVE MATRIX WITH TWO DIODES PER POINT, WITHOUT SPECIFIC RESET CONDUCTOR |
US5164809A (en) | 1989-04-21 | 1992-11-17 | The Regents Of The University Of Calif. | Amorphous silicon radiation detectors |
US5262649A (en) | 1989-09-06 | 1993-11-16 | The Regents Of The University Of Michigan | Thin-film, flat panel, pixelated detector array for real-time digital imaging and dosimetry of ionizing radiation |
JPH0463476A (en) | 1990-07-03 | 1992-02-28 | Mitsubishi Kasei Corp | Image reading element |
US5331183A (en) | 1992-08-17 | 1994-07-19 | The Regents Of The University Of California | Conjugated polymer - acceptor heterojunctions; diodes, photodiodes, and photovoltaic cells |
US5504323A (en) | 1993-12-07 | 1996-04-02 | The Regents Of The University Of California | Dual function conducting polymer diodes |
US5523555A (en) | 1994-09-14 | 1996-06-04 | Cambridge Display Technology | Photodetector device having a semiconductive conjugated polymer |
-
1999
- 1999-02-02 KR KR1020007008373A patent/KR20010040510A/en not_active Application Discontinuation
- 1999-02-02 CN CN99804729A patent/CN1295721A/en active Pending
- 1999-02-02 US US09/241,660 patent/US6303943B1/en not_active Expired - Lifetime
- 1999-02-02 JP JP2000529759A patent/JP2002502129A/en active Pending
- 1999-02-02 EP EP99904548A patent/EP1055260A1/en not_active Withdrawn
- 1999-02-02 WO PCT/US1999/002247 patent/WO1999039395A1/en not_active Application Discontinuation
- 1999-02-02 AU AU24925/99A patent/AU2492599A/en not_active Abandoned
- 1999-02-02 CA CA002319536A patent/CA2319536A1/en not_active Abandoned
-
2001
- 2001-08-16 US US09/930,771 patent/US20020017612A1/en not_active Abandoned
Cited By (114)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20050040390A1 (en) * | 2002-02-20 | 2005-02-24 | Martin Pfeiffer | Doped organic semiconductor material and method for production thereof |
US7858967B2 (en) * | 2002-02-20 | 2010-12-28 | Novaled Ag | Doped semiconductor material and process for production thereof |
EP1376663A3 (en) * | 2002-06-28 | 2005-04-13 | Hewlett-Packard Development Company, L.P. | Method and system for forming a semiconductor device |
EP1376663A2 (en) * | 2002-06-28 | 2004-01-02 | Hewlett-Packard Development Company, L.P. | Method and system for forming a semiconductor device |
US20060065841A1 (en) * | 2002-08-15 | 2006-03-30 | Iiro Hietanen | Packaging structure for imaging detectors |
WO2004017429A1 (en) * | 2002-08-15 | 2004-02-26 | Detection Technology Oy | Packaging structure for imaging detectors |
US7375340B2 (en) | 2002-08-15 | 2008-05-20 | Detection Technology Oy | Packaging structure for imaging detectors |
CN100407445C (en) * | 2002-08-15 | 2008-07-30 | 地太科特技术有限公司 | Packaging structure for imaging detectors |
GB2392308B (en) * | 2002-08-15 | 2006-10-25 | Detection Technology Oy | Packaging structure for imaging detectors |
US20040113085A1 (en) * | 2002-09-23 | 2004-06-17 | Bjoern Heismann | Image detector for X-ray radiation |
US7081627B2 (en) * | 2002-09-23 | 2006-07-25 | Siemens Aktiengesellschaft | Image detector for X-ray radiation |
US20090072201A1 (en) * | 2002-09-24 | 2009-03-19 | E. I. Du Pont De Nemours And Company | Water dispersible polyanilines made with polymeric acid colloids for electronics applications |
US8318046B2 (en) | 2002-09-24 | 2012-11-27 | E I Du Pont De Nemours And Company | Water dispersible polyanilines made with polymeric acid colloids for electronics applications |
US20110155966A1 (en) * | 2002-09-24 | 2011-06-30 | E.I. Du Pont De Nemours And Company | Electrically conducting organic polymer/nanoparticle composites and methods for use thereof |
US8585931B2 (en) | 2002-09-24 | 2013-11-19 | E I Du Pont De Nemours And Company | Water dispersible polythiophenes made with polymeric acid colloids |
US8455865B2 (en) | 2002-09-24 | 2013-06-04 | E I Du Pont De Nemours And Company | Electrically conducting organic polymer/nanoparticle composites and methods for use thereof |
US8784692B2 (en) | 2002-09-24 | 2014-07-22 | E I Du Pont De Nemours And Company | Water dispersible polythiophenes made with polymeric acid colloids |
US20080135809A1 (en) * | 2002-09-24 | 2008-06-12 | Che-Hsiung Hsu | Electrically conducting organic polymer/nanoparticle composites and method for use thereof |
US20080296536A1 (en) * | 2002-09-24 | 2008-12-04 | Che-Hsiung Hsu | Water dispersible polythiophenes made with polymeric acid colloids |
US8338512B2 (en) | 2002-09-24 | 2012-12-25 | E I Du Pont De Nemours And Company | Electrically conducting organic polymer/nanoparticle composites and method for use thereof |
US20050195318A1 (en) * | 2003-02-07 | 2005-09-08 | Takahiro Komatsu | Organic information reading unit and information reading device using the same |
US20040159793A1 (en) * | 2003-02-19 | 2004-08-19 | Christoph Brabec | Carbon-based photodiode detector for nuclear medicine |
US8641926B2 (en) | 2003-04-22 | 2014-02-04 | E I Du Pont De Nemours And Company | Water dispersible polythiophenes made with polymeric acid colloids |
US20080248314A1 (en) * | 2003-04-22 | 2008-10-09 | Che-Hsiung Hsu | Water dispersible polythiophenes made with polymeric acid colloids |
US20060138447A1 (en) * | 2003-06-17 | 2006-06-29 | Nederlandse Organisatie Voor Toegepast- Natuurwetenschappelijk Onderzoek Tno | Light emitting diode |
US8188485B2 (en) * | 2003-06-17 | 2012-05-29 | Nederlandse Organisatie Voor Toegepast-Natuurwetenschappelijk Onderzoek Tno | Detection system having a light emitting diode |
US20040262614A1 (en) * | 2003-06-27 | 2004-12-30 | Michael Hack | Grey scale bistable display |
US7053412B2 (en) | 2003-06-27 | 2006-05-30 | The Trustees Of Princeton University And Universal Display Corporation | Grey scale bistable display |
US8765022B2 (en) | 2004-03-17 | 2014-07-01 | E I Du Pont De Nemours And Company | Water dispersible polypyrroles made with polymeric acid colloids for electronics applications |
US20080142721A1 (en) * | 2004-06-01 | 2008-06-19 | Siemens Aktiengesellschaft | X-Ray Detector |
US8963169B2 (en) | 2004-07-28 | 2015-02-24 | Quantum Semiconductor Llc | CMOS pixels comprising epitaxial layers for light-sensing and light emission |
US20080001139A1 (en) * | 2004-07-28 | 2008-01-03 | Augusto Carols J | Photonic Devices Monolithically Integrated with Cmos |
US11043529B2 (en) | 2004-07-28 | 2021-06-22 | Quantum Semiconductor Llc | CMOS pixels comprising epitaxial layers for light-sensing and light emission |
WO2006010618A1 (en) * | 2004-07-28 | 2006-02-02 | Quantum Semiconductor Llc | Photonic devices monolithically integrated with cmos |
US20060044451A1 (en) * | 2004-08-30 | 2006-03-02 | Eastman Kodak Company | Wide angle lenslet camera |
US20060067472A1 (en) * | 2004-09-30 | 2006-03-30 | Possin George E | Method and apparatus for measuring X-ray energy |
US20060186400A1 (en) * | 2005-02-10 | 2006-08-24 | Japan Science And Technology Agency | Organic photodiode and method for manufacturing the organic photodiode |
US7307297B2 (en) * | 2005-02-10 | 2007-12-11 | Japan Science And Technology Agency | Organic photodiode and method for manufacturing the organic photodiode |
WO2006134114A1 (en) * | 2005-06-17 | 2006-12-21 | Siemens Aktiengesellschaft | Organic pixilated flat panel detector and method for the production thereof |
US8409476B2 (en) | 2005-06-28 | 2013-04-02 | E I Du Pont De Nemours And Company | High work function transparent conductors |
USRE44853E1 (en) | 2005-06-28 | 2014-04-22 | E I Du Pont De Nemours And Company | Buffer compositions |
US7466015B2 (en) * | 2005-08-10 | 2008-12-16 | Jiahn-Chang Wu | Supporting frame for surface-mount diode package |
US20070096275A1 (en) * | 2005-08-10 | 2007-05-03 | Jiahn-Chang Wu | Supporting frame for surface-mount diode package |
US9041851B2 (en) * | 2005-11-15 | 2015-05-26 | The Trustees Of Princeton University | Organic electronic detectors and methods of fabrication |
US20070108890A1 (en) * | 2005-11-15 | 2007-05-17 | Stephen Forrest | Organic electric camera |
US20070116179A1 (en) * | 2005-11-24 | 2007-05-24 | Martin Spahn | Flat image detector |
US20110168952A1 (en) * | 2006-12-29 | 2011-07-14 | E. I. Du Pont De Nemours And Company | High work-function and high conductivity compositions of electrically conducting polymers |
US8491819B2 (en) | 2006-12-29 | 2013-07-23 | E I Du Pont De Nemours And Company | High work-function and high conductivity compositions of electrically conducting polymers |
US20100032551A1 (en) * | 2007-03-01 | 2010-02-11 | Koninklijke Philips Electronics N.V. | Optical detector device |
US8324560B2 (en) * | 2007-03-01 | 2012-12-04 | Koninklijke Philipe Electronics N.V. | Optical detector device |
US20080237770A1 (en) * | 2007-03-30 | 2008-10-02 | Fujifilm Corporation | Radiation detector |
US8071980B2 (en) * | 2007-03-30 | 2011-12-06 | Fujifilm Corporation | Radiation detector |
US8330146B2 (en) * | 2007-05-07 | 2012-12-11 | Chunghwa Picture Tubes, Ltd. | Organic photodetector |
US20080277650A1 (en) * | 2007-05-07 | 2008-11-13 | Chunghwa Picture Tubes, Ltd. | Organic photodetector and fabricating method of organic photodetector and organic thin film transistor |
US20090114884A1 (en) * | 2007-05-18 | 2009-05-07 | Che-Hsiung Hsu | Aqueous dispersions of electrically conducting polymers containing high boiling solvent and additives |
US8241526B2 (en) * | 2007-05-18 | 2012-08-14 | E I Du Pont De Nemours And Company | Aqueous dispersions of electrically conducting polymers containing high boiling solvent and additives |
US20100294936A1 (en) * | 2007-09-13 | 2010-11-25 | Boeberl Michaela | Organic photodetector for the detection of infrared radiation, method for the production thereof, and use thereof |
US8507865B2 (en) * | 2007-09-13 | 2013-08-13 | Siemens Aktiengesellschaft | Organic photodetector for the detection of infrared radiation, method for the production thereof, and use thereof |
US20090108791A1 (en) * | 2007-10-31 | 2009-04-30 | Eiji Isobe | Motor control apparatus |
US20090205698A1 (en) * | 2008-02-14 | 2009-08-20 | Mrinal Thakur | Photovoltaic applications of non-conjugated conductive polymers |
US8723027B2 (en) | 2008-02-14 | 2014-05-13 | Mrinal Thakur | Photovoltaic applications of non-conjugated conductive polymers |
US20140295571A1 (en) * | 2008-12-18 | 2014-10-02 | Bayer Healthcare Llc | Method and assembly for determining the temperature of a test sensor |
CN104297248A (en) * | 2008-12-18 | 2015-01-21 | 拜尔健康护理有限责任公司 | Method and assembly for determining the temperature of a test sensor |
US8945426B2 (en) | 2009-03-12 | 2015-02-03 | E I Du Pont De Nemours And Company | Electrically conductive polymer compositions for coating applications |
US8845933B2 (en) | 2009-04-21 | 2014-09-30 | E I Du Pont De Nemours And Company | Electrically conductive polymer compositions and films made therefrom |
US8945427B2 (en) | 2009-04-24 | 2015-02-03 | E I Du Pont De Nemours And Company | Electrically conductive polymer compositions and films made therefrom |
US20120146006A1 (en) * | 2009-05-20 | 2012-06-14 | David Hartmann | Material for a hole transport layer with p-dopant |
US8610113B2 (en) * | 2009-05-20 | 2013-12-17 | Siemens Aktiengesellschaft | Material for a hole transport layer with p-dopant |
US20110068426A1 (en) * | 2009-09-22 | 2011-03-24 | Intersil Americas Inc. | Photodiodes and methods for fabricating photodiodes |
US20110068255A1 (en) * | 2009-09-22 | 2011-03-24 | Intersil Americas Inc. | Photodetectors useful as ambient light sensors |
US8492699B2 (en) | 2009-09-22 | 2013-07-23 | Intersil Americas Inc. | Photodetectors useful as ambient light sensors having an optical filter rejecting a portion of infrared light |
EP2513995B1 (en) * | 2009-12-16 | 2016-05-11 | Heliatek GmbH | Photoactive component having organic layers |
US10756284B2 (en) | 2009-12-16 | 2020-08-25 | Heliatek Gmbh | Photoactive component having organic layers |
US9451188B2 (en) | 2010-03-19 | 2016-09-20 | Invisage Technologies, Inc. | Dark current reduction in image sensors via dynamic electrical biasing |
US8736733B2 (en) * | 2010-03-19 | 2014-05-27 | Invisage Technologies, Inc. | Dark current reduction in image sensors via dynamic electrical biasing |
US20110228144A1 (en) * | 2010-03-19 | 2011-09-22 | Hui Tian | Dark current reduction in image sensors via dynamic electrical biasing |
US10225504B2 (en) | 2010-03-19 | 2019-03-05 | Invisage Technologies, Inc. | Dark current reduction in image sensors via dynamic electrical biasing |
US8760494B1 (en) * | 2010-05-04 | 2014-06-24 | Lockheed Martin Corporation | UV detection of objects hidden in foliage |
US11211559B2 (en) * | 2010-10-15 | 2021-12-28 | The Regents Of The University Of Michigan | Materials for controlling the epitaxial growth of photoactive layers in photovoltaic devices |
US20120090685A1 (en) * | 2010-10-15 | 2012-04-19 | Forrest Stephen R | Materials for controlling the epitaxial growth of photoactive layers in photovoltaic devices |
WO2012080927A3 (en) * | 2010-12-13 | 2012-11-15 | Koninklijke Philips Electronics N.V. | Radiation detector with photodetectors |
US9354328B2 (en) | 2010-12-13 | 2016-05-31 | Koninklijke Philips N.V. | Radiation detector with photodetectors |
WO2012080927A2 (en) | 2010-12-13 | 2012-06-21 | Koninklijke Philips Electronics N.V. | Radiation detector with photodetectors |
CN103261913A (en) * | 2010-12-13 | 2013-08-21 | 皇家飞利浦电子股份有限公司 | Radiation detector with photodetectors |
DE102010055633A1 (en) * | 2010-12-22 | 2012-06-28 | MAX-PLANCK-Gesellschaft zur Förderung der Wissenschaften e.V. | Semiconductor detector with offset bonding contact |
US9496512B2 (en) | 2011-06-22 | 2016-11-15 | Siemens Aktiengesellschaft | Weak light detection using an organic, photosensitive component |
CN104641206A (en) * | 2012-07-18 | 2015-05-20 | 美高森美公司 | Solid-state photodetector with variable spectral response |
US20140098065A1 (en) * | 2012-10-04 | 2014-04-10 | Corning Incorporated | Touch screen systems and methods for sensing touch screen displacement |
US9619084B2 (en) * | 2012-10-04 | 2017-04-11 | Corning Incorporated | Touch screen systems and methods for sensing touch screen displacement |
USRE47503E1 (en) | 2012-11-21 | 2019-07-09 | Intersil Americas LLC | Photodetectors useful as ambient light sensors and methods for use in manufacturing the same |
US8779542B2 (en) | 2012-11-21 | 2014-07-15 | Intersil Americas LLC | Photodetectors useful as ambient light sensors and methods for use in manufacturing the same |
US20180075191A1 (en) * | 2014-03-06 | 2018-03-15 | Ricoh Company, Ltd. | Film to dicom conversion |
US10104322B2 (en) | 2014-07-31 | 2018-10-16 | Invisage Technologies, Inc. | Image sensors with noise reduction |
US10139275B2 (en) | 2014-10-07 | 2018-11-27 | Technische Universität Dresden | Apparatus for spectrometrically capturing light with a photodiode which is monolithically integrated in the layer structure of a wavelength-selective filter |
WO2016055047A1 (en) * | 2014-10-07 | 2016-04-14 | Technische Universität Dresden | Apparatus for spectrometrically capturing light with a photodiode which is monolithically integrated in the layer structure of a wavelength-selective filter |
US10418539B2 (en) | 2015-02-18 | 2019-09-17 | Savannah River Nuclear Solutions, Llc | Enhanced superconductivity of fullerenes |
US9685600B2 (en) | 2015-02-18 | 2017-06-20 | Savannah River Nuclear Solutions, Llc | Enhanced superconductivity of fullerenes |
US20180159058A1 (en) * | 2016-12-05 | 2018-06-07 | Commissariat à l'énergie atomique et aux énergies alternatives | Infrared photodetector |
US11329240B2 (en) * | 2016-12-05 | 2022-05-10 | Commissariat à l'énergie atomique et aux énergies alternatives | Infrared photodetector |
US11204508B2 (en) | 2017-01-19 | 2021-12-21 | Lockheed Martin Corporation | Multiple band multiple polarizer optical device |
US11439822B2 (en) | 2017-03-31 | 2022-09-13 | ECOLE POLYTECHNIQUE FéDéRALE DE LAUSANNE | Polymer-based optoelectronic interface and methods for its manufacture |
EP3600525B1 (en) * | 2017-03-31 | 2022-08-03 | École Polytechnique Fédérale de Lausanne (EPFL) | Polymer-based optoelectronic interface and methods for its manufacture |
US10425601B1 (en) | 2017-05-05 | 2019-09-24 | Invisage Technologies, Inc. | Three-transistor active reset pixel |
US10976844B2 (en) * | 2017-09-27 | 2021-04-13 | Dongwoo Fine-Chem. Co, Ltd. | Touch sensor and manufacturing method thereof |
US11069869B2 (en) * | 2017-10-23 | 2021-07-20 | Sumitomo Chemical Company, Limited | Photoelectric conversion element and method for producing the same |
US11522017B2 (en) * | 2018-01-15 | 2022-12-06 | Xarpotech UG (Haftungsbeschraenkt) | Organic photoreceptors |
US20210375996A1 (en) * | 2018-01-15 | 2021-12-02 | Xarpotech UG (Haftungsbeschraenkt) | Organic photoreceptors |
US10789467B1 (en) | 2018-05-30 | 2020-09-29 | Lockheed Martin Corporation | Polarization-based disturbed earth identification |
US11550407B2 (en) | 2019-01-18 | 2023-01-10 | Semiconductor Energy Laboratory Co., Ltd. | Display system, display device, and light-emitting apparatus |
WO2021108678A1 (en) * | 2019-11-27 | 2021-06-03 | The Regents Of The University Of California | Uncooled infrared photodetectors |
US20210364438A1 (en) * | 2020-05-20 | 2021-11-25 | Ysi, Inc. | Spatial gradient-based fluorometer |
US20210364430A1 (en) * | 2020-05-20 | 2021-11-25 | Ysi, Inc. | Extended solid angle turbidity sensor |
US11604143B2 (en) * | 2020-05-20 | 2023-03-14 | Ysi, Inc. | Spatial gradient-based fluorometer |
US11860096B2 (en) * | 2020-05-20 | 2024-01-02 | Ysi, Inc. | Extended solid angle turbidity sensor |
Also Published As
Publication number | Publication date |
---|---|
CN1295721A (en) | 2001-05-16 |
KR20010040510A (en) | 2001-05-15 |
JP2002502129A (en) | 2002-01-22 |
US6303943B1 (en) | 2001-10-16 |
AU2492599A (en) | 1999-08-16 |
CA2319536A1 (en) | 1999-08-05 |
EP1055260A1 (en) | 2000-11-29 |
WO1999039395A1 (en) | 1999-08-05 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US6303943B1 (en) | Organic diodes with switchable photosensitivity useful in photodetectors | |
US6483099B1 (en) | Organic diodes with switchable photosensitivity | |
US6300612B1 (en) | Image sensors made from organic semiconductors | |
WO1999009603A9 (en) | Organic diodes with switchable photosensitivity | |
US6441395B1 (en) | Column-row addressable electric microswitch arrays and sensor matrices employing them | |
US7129466B2 (en) | Color image pickup device and color light-receiving device | |
CN204720453U (en) | Photo-electric conversion element, solid camera head and electronic equipment | |
JP4817584B2 (en) | Color image sensor | |
US20150014627A1 (en) | Two-terminal electronic devices and their methods of fabrication | |
CN104425717A (en) | Organic photodiode with dual electron-blocking layers | |
JP2004165242A (en) | Color imaging device and color light receiving element | |
US20170077431A1 (en) | Organic photoelectric conversion device | |
Yu et al. | Large area, full-color, digital image sensors made with semiconducting polymers | |
Yu et al. | Large area, full-color image sensors made with organic semiconductors | |
JP2007043534A (en) | Image sensor |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |