KR101728602B1 - RGB three-band emitting nanocrystals based on ZnSe and preparation method therof - Google Patents
RGB three-band emitting nanocrystals based on ZnSe and preparation method therof Download PDFInfo
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- KR101728602B1 KR101728602B1 KR1020150069980A KR20150069980A KR101728602B1 KR 101728602 B1 KR101728602 B1 KR 101728602B1 KR 1020150069980 A KR1020150069980 A KR 1020150069980A KR 20150069980 A KR20150069980 A KR 20150069980A KR 101728602 B1 KR101728602 B1 KR 101728602B1
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- znse
- nanocrystals
- dopant
- reaction flask
- oleic acid
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- 239000002159 nanocrystal Substances 0.000 title claims abstract description 145
- SBIBMFFZSBJNJF-UHFFFAOYSA-N selenium;zinc Chemical compound [Se]=[Zn] SBIBMFFZSBJNJF-UHFFFAOYSA-N 0.000 title claims abstract 8
- 238000002360 preparation method Methods 0.000 title abstract description 5
- ZQPPMHVWECSIRJ-KTKRTIGZSA-N oleic acid group Chemical group C(CCCCCCC\C=C/CCCCCCCC)(=O)O ZQPPMHVWECSIRJ-KTKRTIGZSA-N 0.000 claims abstract description 63
- 239000002019 doping agent Substances 0.000 claims abstract description 51
- WRIDQFICGBMAFQ-UHFFFAOYSA-N (E)-8-Octadecenoic acid Natural products CCCCCCCCCC=CCCCCCCC(O)=O WRIDQFICGBMAFQ-UHFFFAOYSA-N 0.000 claims abstract description 42
- LQJBNNIYVWPHFW-UHFFFAOYSA-N 20:1omega9c fatty acid Natural products CCCCCCCCCCC=CCCCCCCCC(O)=O LQJBNNIYVWPHFW-UHFFFAOYSA-N 0.000 claims abstract description 42
- QSBYPNXLFMSGKH-UHFFFAOYSA-N 9-Heptadecensaeure Natural products CCCCCCCC=CCCCCCCCC(O)=O QSBYPNXLFMSGKH-UHFFFAOYSA-N 0.000 claims abstract description 42
- ZQPPMHVWECSIRJ-UHFFFAOYSA-N Oleic acid Natural products CCCCCCCCC=CCCCCCCCC(O)=O ZQPPMHVWECSIRJ-UHFFFAOYSA-N 0.000 claims abstract description 42
- 239000005642 Oleic acid Substances 0.000 claims abstract description 42
- QXJSBBXBKPUZAA-UHFFFAOYSA-N isooleic acid Natural products CCCCCCCC=CCCCCCCCCC(O)=O QXJSBBXBKPUZAA-UHFFFAOYSA-N 0.000 claims abstract description 42
- 238000006243 chemical reaction Methods 0.000 claims abstract description 40
- 238000000034 method Methods 0.000 claims abstract description 20
- 239000011669 selenium Substances 0.000 claims abstract description 20
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims abstract description 19
- CCCMONHAUSKTEQ-UHFFFAOYSA-N octadecene Natural products CCCCCCCCCCCCCCCCC=C CCCMONHAUSKTEQ-UHFFFAOYSA-N 0.000 claims abstract description 19
- 229910052711 selenium Inorganic materials 0.000 claims abstract description 16
- 239000012046 mixed solvent Substances 0.000 claims abstract description 15
- 239000002243 precursor Substances 0.000 claims abstract description 15
- ZMBHCYHQLYEYDV-UHFFFAOYSA-N trioctylphosphine oxide Chemical compound CCCCCCCCP(=O)(CCCCCCCC)CCCCCCCC ZMBHCYHQLYEYDV-UHFFFAOYSA-N 0.000 claims abstract description 15
- BUGBHKTXTAQXES-UHFFFAOYSA-N Selenium Chemical compound [Se] BUGBHKTXTAQXES-UHFFFAOYSA-N 0.000 claims abstract description 14
- TUQOTMZNTHZOKS-UHFFFAOYSA-N tributylphosphine Chemical compound CCCCP(CCCC)CCCC TUQOTMZNTHZOKS-UHFFFAOYSA-N 0.000 claims abstract description 13
- 150000003752 zinc compounds Chemical class 0.000 claims abstract description 13
- 238000010438 heat treatment Methods 0.000 claims abstract description 10
- 239000002244 precipitate Substances 0.000 claims abstract description 6
- 238000001816 cooling Methods 0.000 claims abstract description 5
- 230000002431 foraging effect Effects 0.000 claims abstract description 5
- 229910001437 manganese ion Inorganic materials 0.000 claims description 9
- WAEMQWOKJMHJLA-UHFFFAOYSA-N Manganese(2+) Chemical compound [Mn+2] WAEMQWOKJMHJLA-UHFFFAOYSA-N 0.000 claims description 8
- 229910001431 copper ion Inorganic materials 0.000 claims description 5
- JPVYNHNXODAKFH-UHFFFAOYSA-N Cu2+ Chemical group [Cu+2] JPVYNHNXODAKFH-UHFFFAOYSA-N 0.000 claims description 4
- PFNQVRZLDWYSCW-UHFFFAOYSA-N (fluoren-9-ylideneamino) n-naphthalen-1-ylcarbamate Chemical compound C12=CC=CC=C2C2=CC=CC=C2C1=NOC(=O)NC1=CC=CC2=CC=CC=C12 PFNQVRZLDWYSCW-UHFFFAOYSA-N 0.000 description 165
- 239000011572 manganese Substances 0.000 description 54
- 239000010949 copper Substances 0.000 description 50
- 239000000243 solution Substances 0.000 description 27
- 150000002500 ions Chemical class 0.000 description 20
- 239000013078 crystal Substances 0.000 description 18
- 238000005424 photoluminescence Methods 0.000 description 18
- 239000002245 particle Substances 0.000 description 14
- 230000015572 biosynthetic process Effects 0.000 description 11
- 239000003446 ligand Substances 0.000 description 11
- 239000007787 solid Substances 0.000 description 11
- 229910052984 zinc sulfide Inorganic materials 0.000 description 11
- 229910052802 copper Inorganic materials 0.000 description 10
- 238000002173 high-resolution transmission electron microscopy Methods 0.000 description 10
- 238000001228 spectrum Methods 0.000 description 10
- 239000011701 zinc Substances 0.000 description 10
- 229910021645 metal ion Inorganic materials 0.000 description 9
- 230000003287 optical effect Effects 0.000 description 9
- 238000005079 FT-Raman Methods 0.000 description 8
- 239000000203 mixture Substances 0.000 description 8
- 238000010586 diagram Methods 0.000 description 7
- 238000002371 ultraviolet--visible spectrum Methods 0.000 description 7
- 229910052725 zinc Inorganic materials 0.000 description 7
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 6
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 6
- 238000010521 absorption reaction Methods 0.000 description 6
- 238000000295 emission spectrum Methods 0.000 description 6
- 238000002354 inductively-coupled plasma atomic emission spectroscopy Methods 0.000 description 6
- 229910052748 manganese Inorganic materials 0.000 description 6
- 238000006862 quantum yield reaction Methods 0.000 description 6
- 238000005033 Fourier transform infrared spectroscopy Methods 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 239000002105 nanoparticle Substances 0.000 description 5
- 238000000103 photoluminescence spectrum Methods 0.000 description 5
- 230000008569 process Effects 0.000 description 5
- 238000001157 Fourier transform infrared spectrum Methods 0.000 description 4
- UHYPYGJEEGLRJD-UHFFFAOYSA-N cadmium(2+);selenium(2-) Chemical compound [Se-2].[Cd+2] UHYPYGJEEGLRJD-UHFFFAOYSA-N 0.000 description 4
- 230000008859 change Effects 0.000 description 4
- VYXSBFYARXAAKO-WTKGSRSZSA-N chembl402140 Chemical compound Cl.C1=2C=C(C)C(NCC)=CC=2OC2=C\C(=N/CC)C(C)=CC2=C1C1=CC=CC=C1C(=O)OCC VYXSBFYARXAAKO-WTKGSRSZSA-N 0.000 description 4
- 230000007547 defect Effects 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 239000002904 solvent Substances 0.000 description 4
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 3
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 3
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
- 238000002441 X-ray diffraction Methods 0.000 description 3
- 238000007796 conventional method Methods 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 239000011259 mixed solution Substances 0.000 description 3
- 230000006798 recombination Effects 0.000 description 3
- 238000005215 recombination Methods 0.000 description 3
- 239000004065 semiconductor Substances 0.000 description 3
- 239000004054 semiconductor nanocrystal Substances 0.000 description 3
- 229910001428 transition metal ion Inorganic materials 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 238000005169 Debye-Scherrer Methods 0.000 description 2
- 229910021536 Zeolite Inorganic materials 0.000 description 2
- 238000002835 absorbance Methods 0.000 description 2
- 238000005102 attenuated total reflection Methods 0.000 description 2
- 244000309464 bull Species 0.000 description 2
- 229910052793 cadmium Inorganic materials 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 2
- 239000002800 charge carrier Substances 0.000 description 2
- 239000007810 chemical reaction solvent Substances 0.000 description 2
- 230000000295 complement effect Effects 0.000 description 2
- OPQARKPSCNTWTJ-UHFFFAOYSA-L copper(ii) acetate Chemical compound [Cu+2].CC([O-])=O.CC([O-])=O OPQARKPSCNTWTJ-UHFFFAOYSA-L 0.000 description 2
- 230000001419 dependent effect Effects 0.000 description 2
- 230000005284 excitation Effects 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 230000033001 locomotion Effects 0.000 description 2
- 238000004020 luminiscence type Methods 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 239000003960 organic solvent Substances 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 238000000197 pyrolysis Methods 0.000 description 2
- 238000010791 quenching Methods 0.000 description 2
- 230000000171 quenching effect Effects 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- WGPCGCOKHWGKJJ-UHFFFAOYSA-N sulfanylidenezinc Chemical compound [Zn]=S WGPCGCOKHWGKJJ-UHFFFAOYSA-N 0.000 description 2
- 229910052717 sulfur Inorganic materials 0.000 description 2
- 230000002194 synthesizing effect Effects 0.000 description 2
- 239000010457 zeolite Substances 0.000 description 2
- XOOUIPVCVHRTMJ-UHFFFAOYSA-L zinc stearate Chemical compound [Zn+2].CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O XOOUIPVCVHRTMJ-UHFFFAOYSA-L 0.000 description 2
- YZAZXIUFBCPZGB-QZOPMXJLSA-N (z)-octadec-9-enoic acid Chemical compound CCCCCCCC\C=C/CCCCCCCC(O)=O.CCCCCCCC\C=C/CCCCCCCC(O)=O YZAZXIUFBCPZGB-QZOPMXJLSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 238000003775 Density Functional Theory Methods 0.000 description 1
- YZCKVEUIGOORGS-OUBTZVSYSA-N Deuterium Chemical compound [2H] YZCKVEUIGOORGS-OUBTZVSYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 238000003917 TEM image Methods 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- PTFCDOFLOPIGGS-UHFFFAOYSA-N Zinc dication Chemical compound [Zn+2] PTFCDOFLOPIGGS-UHFFFAOYSA-N 0.000 description 1
- 229910007609 Zn—S Inorganic materials 0.000 description 1
- 238000000862 absorption spectrum Methods 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 125000000129 anionic group Chemical group 0.000 description 1
- 239000003125 aqueous solvent Substances 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 150000001732 carboxylic acid derivatives Chemical group 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 125000002091 cationic group Chemical group 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 239000002178 crystalline material Substances 0.000 description 1
- 238000007405 data analysis Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 229910052805 deuterium Inorganic materials 0.000 description 1
- HQWPLXHWEZZGKY-UHFFFAOYSA-N diethylzinc Chemical compound CC[Zn]CC HQWPLXHWEZZGKY-UHFFFAOYSA-N 0.000 description 1
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 1
- 230000008034 disappearance Effects 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000000921 elemental analysis Methods 0.000 description 1
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- 239000000835 fiber Substances 0.000 description 1
- 229910017053 inorganic salt Inorganic materials 0.000 description 1
- 230000002452 interceptive effect Effects 0.000 description 1
- UOGMEBQRZBEZQT-UHFFFAOYSA-L manganese(2+);diacetate Chemical compound [Mn+2].CC([O-])=O.CC([O-])=O UOGMEBQRZBEZQT-UHFFFAOYSA-L 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000002114 nanocomposite Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- SWMBQMGPRYJSCI-UHFFFAOYSA-N octylphosphane Chemical compound CCCCCCCCP SWMBQMGPRYJSCI-UHFFFAOYSA-N 0.000 description 1
- 125000002524 organometallic group Chemical group 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 238000000628 photoluminescence spectroscopy Methods 0.000 description 1
- 239000002096 quantum dot Substances 0.000 description 1
- 230000002285 radioactive effect Effects 0.000 description 1
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- 239000012925 reference material Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
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- 238000004611 spectroscopical analysis Methods 0.000 description 1
- 238000010183 spectrum analysis Methods 0.000 description 1
- 239000012086 standard solution Substances 0.000 description 1
- 239000011550 stock solution Substances 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 239000006228 supernatant Substances 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
- 238000001845 vibrational spectrum Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 229910052724 xenon Inorganic materials 0.000 description 1
- FHNFHKCVQCLJFQ-UHFFFAOYSA-N xenon atom Chemical compound [Xe] FHNFHKCVQCLJFQ-UHFFFAOYSA-N 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
- C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
- C09K11/54—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing zinc or cadmium
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
- C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
- C09K11/88—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing selenium, tellurium or unspecified chalcogen elements
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/48—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
- H01L33/50—Wavelength conversion elements
- H01L33/501—Wavelength conversion elements characterised by the materials, e.g. binder
- H01L33/502—Wavelength conversion materials
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B33/00—Electroluminescent light sources
- H05B33/12—Light sources with substantially two-dimensional radiating surfaces
- H05B33/14—Light sources with substantially two-dimensional radiating surfaces characterised by the chemical or physical composition or the arrangement of the electroluminescent material, or by the simultaneous addition of the electroluminescent material in or onto the light source
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Abstract
The present invention relates to a method for preparing oleic acid-capped ZnSe-based nanocrystals having emission peaks in the visible light region, and ZnSe-based nanocrystals comprising the oleic acid-capped dopants having emission peaks in the visible light region, A first step of heating a zinc compound solution obtained by dissolving a zinc compound in a mixed solvent of octadecene and oleic acid in a reaction flask to 250 to 350 ° C; A second step of preparing a heterogeneous selenium precursor solution by dispersing selenium powder in a mixed solvent of tri-n-butylphosphine or trioctylphosphine oxide and octadecene in a separate reaction flask; A third step of adding the solution prepared in the second step to the reaction flask in the first step; The reaction flask in the third step is cooled to 170 to 230 ° C and a dopant solution prepared by dissolving a dopant in a mixed solvent of tri-n-butylphosphine or trioctylphosphine oxide and octadecene is added to the reaction flask Step 4; A fifth step of heating the reaction flask of the fourth step to 200 to 270 DEG C and maintaining the temperature at the corresponding temperature for 1 hour to 3 hours for aging; And a sixth step of slowly cooling the reaction flask of the fifth step to 10 to 35 DEG C and adding precipitated ethanol to form a precipitate. The preparation of oleic acid-capped ZnSe-based nanocrystals having an emission peak in the visible light region ≪ / RTI >
Description
The present invention relates to a method for preparing oleic acid-capped ZnSe-based nanocrystals having emission peaks in the visible light region, and ZnSe-based nanocrystals comprising the oleic acid-capped dopants having emission peaks in the visible light region, A first step of heating a zinc compound solution obtained by dissolving a zinc compound in a mixed solvent of octadecene and oleic acid in a reaction flask to 250 to 350 ° C; A second step of preparing a heterogeneous selenium precursor solution by dispersing selenium powder in a mixed solvent of tri-n-butylphosphine or trioctylphosphine oxide and octadecene in a separate reaction flask; A third step of adding the solution prepared in the second step to the reaction flask in the first step; The reaction flask in the third step is cooled to 170 to 230 ° C and a dopant solution prepared by dissolving a dopant in a mixed solvent of tri-n-butylphosphine or trioctylphosphine oxide and octadecene is added to the reaction flask Step 4; A fifth step of heating the reaction flask of the fourth step to 200 to 270 DEG C and maintaining the temperature at the corresponding temperature for 1 hour to 3 hours for aging; And a sixth step of slowly cooling the reaction flask of the fifth step to 10 to 35 DEG C and adding precipitated ethanol to form a precipitate. The preparation of oleic acid-capped ZnSe-based nanocrystals having an emission peak in the visible light region ≪ / RTI >
Low-dimensional semiconductor nanocrystals are an important component of the next generation of advanced electronic devices. The nanocrystals provide inherent physical, chemical and optical properties and are therefore widely applied in non-linear optical and electroluminescent devices, and biomedical applications. The most widely recognized feature of nanocrystals is that they exhibit size-dependent optical properties due to band gap energy differences between materials of the same chemical composition. Zinc selenide (ZnSe) -based semiconductor nanocrystals are of interest due to their strong UV blue luminescence properties at 2.7 eV bandgap, which is difficult to observe in other nanocomposite materials such as CdSe and ZnS. In addition, modified nanocrystals in the form of ZnSe / ZnS core-shells showed much higher quantum efficiency and thermal stability at room temperature than pure ZnSe nanocrystals, which is a very important property for commercial electro-luminescent applications.
The white light emitting phosphors include solid state light emitting diodes; LED). ≪ / RTI > In such an apparatus, the white light emission can be obtained by mixing complementary color emitting phosphors such as GaN (blue) and YAG: Ce (yellow). In addition, recent studies on white light emitting nanocrystals have focused primarily on CdSe quantum dots, which can emit both blue and yellow light by precisely controlling particle size. The present inventors have previously proposed a method for synthesizing ZnSe: Mn nanocrystals that emit white light formed by pyrolysis reaction of diethylzinc, manganese (II) cyclohexabutyrate and selenium element dispersed in TOPO solvent (Lee , SM and Hwang, CS, Bull . Kor . Chem . Soc . , 2013, 34: 321). The PL spectra obtained from ZnSe: Mn nanocrystals showed two broad emission peaks at 445 nm and 572 nm, and the combination of these complementary color emissions produced white light emission. We have also reported mixtures of ZnS-based nanocrystals that emit white light in aqueous solvents (Lee, JW and Hwang, CS, Bull . Kor . Chem . Soc . , 2014, 35: 189). Although it was possible to achieve white light emission by mixing ZnS-based nanocrystals in the proper ratio, it was impossible to obtain a perfect RGB color combination from ZnS-based nanocrystals.
As a result of intensive researches to provide a ZnSe-based nanocrystal that emits a new RGB color for a three-wavelength white light emitting diode, the present inventors have found that doping Cu and Mn with a predetermined concentration, The nanocrystals formed are capped with oleic acid to form ZnSe: Cu nanocrystals capped with oleic acid and emitting green light in the range of 500 to 570 nm, respectively, and red light in the range of 600 to 665 nm Mn nanocrystals capped with oleic acid that emits oxides of nitrogen and oxygen, and completed the present invention.
In order to accomplish the above object, the first aspect of the present invention is a method for producing a zinc compound, comprising the steps of: heating a zinc compound solution obtained by dissolving a zinc compound in a mixed solvent of octadecene and oleic acid in a reaction flask to 250 to 350 ° C; A second step of preparing a heterogeneous selenium precursor solution by dispersing selenium powder in a mixed solvent of tri-n-butylphosphine or trioctylphosphine oxide and octadecene in a separate reaction flask; A third step of adding the solution prepared in the second step to the reaction flask in the first step; The reaction flask in the third step is cooled to 170 to 230 ° C and a dopant solution prepared by dissolving a dopant in a mixed solvent of tri-n-butylphosphine or trioctylphosphine oxide and octadecene is added to the reaction flask Step 4; A fifth step of heating the reaction flask of the fourth step to 200 to 270 DEG C and maintaining the temperature at the corresponding temperature for 1 hour to 3 hours for aging; And a sixth step of slowly cooling the reaction flask of the fifth step to 10 to 35 DEG C and adding precipitated ethanol to form a precipitate. The preparation of oleic acid-capped ZnSe-based nanocrystals having an emission peak in the visible light region ≪ / RTI >
A second aspect of the present invention provides a ZnSe-based nanocrystal comprising an oleic acid-capped dopant having an emission peak in the visible light region produced by the method according to the first aspect of the present invention.
Hereinafter, the present invention will be described in more detail.
The ZnSe-based nanocrystals of the present invention are capped with oleic acid and controlled in size, and the type and concentration of the dopant are adjusted to adjust the wavelength of the emitted nanocrystals and their fabrication method. The present invention relates to a nanocrystal having copper and manganese doped with copper ZnSe-based nanocrystals whose emission wavelengths are shifted to a green light region in the range of 500 to 570 nm and a red light region in the range of 600 to 665 nm are manufactured. However, unlike the conventional method of treating the dopant solution after nanocrystal formation, After doping the crystal with Zn and Se compound solution, the dopant was inserted into the nanocrystals formed by doping the dopant solution, so that the luminescence wavelength was shifted to a longer wavelength to obtain 665 nm pure red of manganese doped ZnSe nanocrystals It is possible to emit light.
That is, in the case of semiconductor quantum dots such as ZnSe, it is known that the emission wavelength can be controlled by controlling the size and the type and concentration of the dopant introduced therein. However, in the conventional method for producing nanocrystals, Moving the wavelength was not achieved. That is, even though three kinds of nanocrystals having different emission wavelengths are mixed to provide three-way white light, when the emission wavelength of individual nanocrystals is analyzed, the longest wavelength shift is 600 nm, No particles emitting red light were produced.
The oleic acid-capped ZnSe-based nanocrystals having emission peaks in the visible light region according to the present invention can be prepared by a first step of heating a zinc compound solution obtained by dissolving a zinc compound in a mixed solvent of octadecene and oleic acid to 250 to 350 ° C; A second step of preparing a heterogeneous selenium precursor solution by dispersing selenium powder in a mixed solvent of tri-n-butylphosphine or trioctylphosphine oxide and octadecene in a separate reaction flask; A third step of adding the solution prepared in the second step to the reaction flask in the first step; The reaction flask in the third step is cooled to 170 to 230 ° C and a dopant solution prepared by dissolving a dopant in a mixed solvent of tri-n-butylphosphine or trioctylphosphine oxide and octadecene is added to the reaction flask Step 4; A fifth step of heating the reaction flask of the fourth step to 200 to 270 DEG C and maintaining the temperature at the corresponding temperature for 1 hour to 3 hours for aging; And the sixth step of slowly cooling the reaction flask of the fifth step to 10 to 35 DEG C and adding precipitated ethanol to form precipitate.
That is, the zinc compound solution, the selenium precursor solution and the dopant solution are independently prepared, and after the zinc compound solution and the selenium precursor solution are mixed, the dopant solution is added to form ZnSe parent crystals, ZnSe-based nanocrystals are formed on the surface of the substrate, as well as on the surface of the substrate. At this time, the temperature can be adjusted to the above-mentioned range to suit each step.
The nanocrystals prepared by including oleic acid in the reaction solvent can be made into nanocrystals of uniform size having a diameter in the range of 2 to 10 nm by controlling the size thereof.
The content of the dopant may be 0.3 to 1.5 atomic% based on ZnSe. If the content of the dopant is less than 0.3 atomic%, the effect on the movement of the emission wavelength is small and it may be difficult to achieve the desired emission wavelength. On the other hand, when the dopant content exceeds 1.5 atomic%, the long wavelength shift does not occur and the emission efficiency can be reduced.
The dopant may be a copper ion or a manganese ion, but is not limited thereto. Any metal ion that can be inserted into the ZnSe parent crystal and move the emission wavelength by a long wavelength can be used without limitation.
For example, when copper ions are used as a dopant, nanocrystals emitting green light in the range of 500 to 570 nm can be produced. When manganese ions are used as dopants, red light in the range of 600 to 665 nm Emitting nanocrystals can be produced.
The method of manufacturing the RGB-based three-dimensional luminescent nanocrystals based on ZnSe according to the present invention prevents the increase of the size of the nanocrystals formed due to the inclusion of oleic acid in the reaction solvent, ZnSe nanocrystals can be controlled by controlling the concentration of ZnSe nanocrystals. Unlike the conventional method of treating ZnSe nanocrystals after the formation of dopants, Zn and Se are reacted with the dopant solution, The nanocrystals doped with metal ions are doped to the inside of the particles to provide ZnSe-based nanocrystals with longer wavelength shifts. Thus, the emission wavelengths of manganese-doped nanocrystals are up to 665 nm And thus can emit pure red light. Therefore, doping that emits blue light Can be usefully applied to the production of nanocrystals capable of RGB triode emission together with non-oleic capped ZnSe.
FIG. 1 is a diagram showing a high-resolution transmission electron microscopy (HR-TEM) image of (a) ZnSe, (b) ZnSe: Cu and (c) ZnSe: Mn nanocrystals.
Figure 2 shows X-ray diffraction of bulk ZnSe solids on (a) ZnSe, (b) ZnSe: Cu and (c) ZnSe: Mn nanocrystals and (d) on zinc blende. XRD) pattern.
3 is a diagram showing a UV-Vis absorption spectrum of ZnSe (blue), ZnSe: Cu (green) and ZnSe: Mn (red) nanocrystals.
4 shows photoluminescence (PL) emission spectra of ZnSe (blue), ZnSe: Cu (green) and ZnSe: Mn (red) nanocrystals.
5 is a graph showing PL emission spectra of undoped ZnSe (blue), ZnSe: Cu (0.25% Cu, cyan) and ZnSe: Cu (1.16% Cu, green) nanocrystals.
6 is a CIE chromaticity diagram of ZnSe-based nanocrystals. ZnSe has (0.15, 0.16), ZnSe: Cu has (0.22, 0.57) and ZnSe: Mn has (0.62, 0.35) color coordinates.
FIG. 7 shows FT-IR spectra of oleic acid molecules (red) and pure oleic acid molecules (black) capped on ZnSe nanocrystals.
FIG. 8 shows FT-Raman spectra of oleic acid molecules (red) and pure oleic acid molecules (black) capped on ZnSe nanocrystals.
Hereinafter, the present invention will be described in more detail with reference to Examples. These examples are for further illustrating the present invention, and the scope of the present invention is not limited by these examples.
Example
1: Device
To confirm the optical properties of the synthesized nanocrystals, UV-Vis absorption spectra were measured using a Perkin Elmer Lambda 25 spectrophotometer equipped with a deuterium / tungsten lamp. The phospholuminescence (PL) spectrum of the room temperature solution was measured using a Perkin Elmer LS-45 spectrophotometer with a 500 W xenon lamp, a 0.275 m triple grating monochrometer, and a
Example
2: oleic acid
Capped
,
ZnSe
-Based nanocrystals
In order to synthesize oleic acid-capped, ZnSe-based nanocrystals, heterogeneous Cd and Se precursors in the form of a mixture of several organic solvents were used to prepare a heterogeneous system in a solvent mixture composed of several organic solvents initiated by Flamee and co- a method of synthesizing CdSe nanocrystals using heterogeneous Cd and Se precursors and a few modified methods (Flamee, S. et al . , Chem . Mater . , 2013, 25: 2476). Specifically, 0.24 g zinc (II) stearate (0.4 mmol) was dissolved in 50 ml of a mixed solution of octadecene (ODE, 30 ml) and oleic acid (OA, 20 ml). The mixed solution was heated to about 300 캜 under argon flow. In a separate flask, 0.32 g of selenium powder was dissolved in 4 ml of tri-n-butyl phosphine (TBP) and 10 ml of ODE to prepare a heterogeneous Se precursor. A very intense reaction occurred when the Se precursor mixture was added rapidly to a flask containing a zinc (II) stearate complex. For the doping process, the reaction flask was cooled to about 200 ° C and a pre-prepared TBP / ODE stock solution containing 0.008 mmol of copper (II) acetate or manganese (II) acetate was added to the reaction flask via a free syringe. The temperature was slowly increased to about 240 ° C and the mixture was held at that temperature for 2 hours for the aging process. Slowly cooled to ambient temperature and anhydrous methanol was added to form a yellow-white precipitate on the bottom of the flask. Finally, the mixture was centrifuged and the supernatant was taken out to separate the obtained solid. The solid was further washed with toluene and 2-propanol and then dried in a vacuum oven for 24 hours. Various spectroscopic experiments were performed on the solids obtained and the results are shown in Table 1 below.
Example
3:
Photoluminescence
Measure efficiency
The PL efficiency of ZnSe-based nanocrystals was measured and calculated by the method disclosed by Williams and co-workers (Rhys-Williams, AT et al . , Analyst , 1983,108: 1067). Specifically, the relative quantum yield (relative) was compared with the value for a 1.0 x 10 -5 M ethanol solution of rhodamine 6G, a reference material disclosed in the literature (Melhuish, WH, J. Phys . Chem . , 1961, 65: 229) quantum yield. The emission wavelengths and absolute quantum yields reported for rhodamine 6G were 566 nm and 0.95 (@ 22 ° C), respectively. The excitation wavelength used for the standard was determined from the UV / Vis spectra of ZnSe-based nanocrystals. The emission spectra for the standard and comparative nanocrystals were recorded in five different concentrations of ethanol solution. A plot of integrated fluorescence intensity versus absorbance for the samples obtained from different concentrations was then plotted. As a result, a straight line with a fairly constant slope was obtained, and the slice was zero. Finally, the relative PL efficiency was calculated using the following equation:
In the above equation, PHI represents PL efficiency. The subscripts ST and x denote the standard and the nanocrystal, respectively. 'Grad' represents the gradient from the integrated fluorescence intensity vs. absorbance plot, and 'η' represents the refractive index of the solvent, which is the same solvent (ethanol in the present invention) for both the standard and the nanocrystals It is an argument that can be omitted.
< Results and Discussion>
The average particle size of the ZnSe-based nanocrystals was measured from the HR-TEM image shown in Fig. These images showed a uniform watery particle shape in the solid state. To measure the particle size, the average particle size for ZnSe-based nanocrystals was calculated by measuring the size of about 20 identifiable particles by maximizing the image. The measured particle sizes were 4.46 ± 1.10 nm for ZnSe, 4.20 ± 0.75 nm for ZnSe: Cu and 4.93 ± 0.83 nm for ZnSe: Mn, the size of ZnSe: Mn capped with an average of 4.2 nm TOPO ligand Respectively. Debye-Scherrer calculations were performed using the obtained XRD data to support the measurement through the TEM image. As shown in Fig. 1, small aggregates were observed between the particles due to solvent evaporation during sample preparation. However, the appearance of lattice planes distinct in the HR-TEM with about 3 Å lattice spacing indicates that the solids obtained were formed of single crystals rather than poly-crystalline aggregates for all of the nanocrystal samples .
Inductively coupled plasma-atomic emission spectrometry (ICP-AES) analysis was performed to accurately determine the elemental composition of the prepared ZnSe-based nanocrystals and the doping concentration of copper and manganese ions. The average elemental proportion of copper and manganese for the ZnSe parent crystal was 1.16 for ZnSe: Cu and 0.8% for ZnSe: Mn from the three-time sample measurements. The intended dopant concentration in ZnSe-based nanocrystals was about 1% for both transition metal ions. This concentration was in agreement with the optimal amount of dopant for ZnS and ZnSe-based nanocrystals to obtain the maximum emission reported in the literature (Yi, G. et al . , J. Mater . Chem . , 2001, 11: 2928).
As shown in FIG. 2, a wide-angle XRD pattern diagram of the ZnSe-based nanocrystalline powder was obtained to confirm the formation of the ZnSe parent crystal lattice. In the diffraction pattern diagram, the apparent peaks in the (111), (220) and (311) planes for the ZnSe-based nanocrystalline powder samples are reported for the bulk ZnSe solids in the reported cubic zinc blende crystalline phase Results. In addition, Debye-Scherrer calculations for ZnSe-based nanocrystals were performed using the obtained XRD peaks to compare with the particle size measured from HR-TEM images. The average particle sizes of ZnSe, ZnSe: Cu and ZnSe: Mn were calculated from the measured full width at half maximum (FWHM) of the selected XRD peaks, which were calculated as 4.12 nm, 3.93 nm and 4.24 nm, respectively. The calculated results were in good agreement with those derived from HR-TEM images in the solid state.
To confirm the optical properties of the ZnSe-based nanocrystals, absorption and emission spectra were measured using a UV-Vis and a PL spectrophotometer. FIG. 3 shows the UV-Vis absorption spectrum of ZnSe-based nanocrystals capped with oleic acid. The diagram shows a broad peak from 400 nm to 450 nm, and the maximum for all ZnSe-based nanocrystals is located at 420 nm. Since these nanocrystals have the same parent crystal, they have very similar absorption wavelengths and peak shapes. FIG. 4 shows the photoluminescence emission spectrum of the room temperature solution obtained from ZnSe-based nanocrystals. As shown in Fig. 4, ZnSe-based nanocrystals exhibited broad emission peaks at 471 nm for ZnSe, 530 nm for ZnSe: Cu and 665 nm for ZnSe: Mn, respectively. The light source was fixed at the maximum absorption wavelength of the UV-Vis spectrum and the emission spectrum was measured. The maximum absorption wavelength was equal to 420 nm for all the nanocrystals, as shown in Fig. The dominant absorption in the UV-Vis spectrum was probably due to the fundamental band-to-band absorption in the ZnSe host. ZnSe-based nanocrystals exhibited increased bandgap due to the quantum confinement effect in nano-sized materials compared to the value for bulk ZnSe solids (2.70 eV). The large Stokes shifts in the range of 110 nm to 245 nm observed in transition metal ion doped ZnSe nanocrystals were consistent with typical characteristics found in nano-sized semiconductor crystalline materials. This phenomenon was mainly due to the recombination of the trapped charge carriers to free carriers. The trapping of the charge carriers was caused by surface defects placed between the bandgap states. Surface defects on the ZnSe-based nanocrystals have probably been caused by incomplete capping by the surfactant oleic acid molecules or from zinc metal cations or selenide anionic vacancies on the surface of the ZnSe crystal lattice.
In the present invention, ZnSe nanocrystals were synthesized by pyrolysis (300 ° C.) of Zn and Se containing organometallic precursor complexes in a tri (n-octyl phosphine) or TOPO (tri-n-octyl phosphine oxide) solvent. In general, ZnSe is present as one of two crystal phases, for example, cubic zeolite or hexagonal wurtzite, indicating that the selection of a particular precursor can lead to the formation of certain crystal phases. The blue light emission of 326 nm for the measured cube ZnSe and 368 nm wavelength for the fiber zinc-zeolite ZnSe was significantly blue shifted from the emission wavelength of the oleic acid-capped isotactic ZnSe (ZnSe-OA) nanocrystals according to the invention of 471 nm Release. Surface defects such as zinc ion vacancies on the surface of more ZnSe nanocrystals are known to induce stronger blue light emission. This indicates that the oleic acid ligand forms more crystal defects than the TOP or TOPO ligands during the nanocrystal formation process, indicating that it is more important to obtain natural blue emission from the ZnSe nanocrystals.
At 530 nm, green light emission results from the recombination between the shallow donor level formed by the sulfur vacancies and the t 2 level of Cu 2+ ions, where the doping concentration of Cu 2 + is important for the luminescent properties of ZnSe: Cu nanocrystals Lt; / RTI > In oleic acid-capped ZnSe: Cu nanocrystals, when the doping concentration of Cu ions determined by ICP-AES decreased to 0.25%, ZnSe: Cu nanocrystals were observed at 434 nm and 491 nm Two broad emission peaks were shown. At this time, the small peak at 434 nm was one of the characteristic emissions originating from Zn ion vacancies in the ZnSe crystal lattice, while the broad emission peak at 491 nm led to the overall blue-green of ZnSe: Cu nanocrystals. This indicates that the increase in the Cu 2 + (d 9 ) ion concentration causes more severe Jahn-Teller distortion than in the ZnSe lattice, and the band gap between the 2 T 2 state and the 2 E state decreases, Lt; / RTI > The oleic acid-capped ZnSe: Cu nanocrystals of the present invention also showed a similar pattern. For example, when more Cu 2 + ions are added, that is, when the Cu ion concentration reaches 1.16%, the oleic acid capped ZnSe: Cu nanocrystals emit at 510 nm from other ZnSe: Cu nanocrystals Produced emission light of 530 nm, which is much closer to the natural green standard for LED lamps. Furthermore, since the increase of the Cu concentration can make the t 2 level of the Cu 2 + ion farther away from the valence band, when the dopant ion concentration exceeds 2 atomic% with respect to the ZnSe host, .
6 is due to the A 1 transformation from Mn nanocrystals, red light emission at 665 nm is 4 T 1 of Mn + 2 ions: ZnSe. The most common emission wavelengths generated from conventional Mn-doped semiconductors, such as CdSe: Mn, ZnS: Mn and ZnSe: Mn nanocrystals capped with other ligands, were in the 570 to 590 nm (yellow-orange) region. However, the emission wavelength can be shifted for some time by changing the [Zn] / [Mn] ratio in these crystals. For example, an increase in the Mn dopant ion concentration in ZnSe: Mn nanocrystals can lead to further doping of Mn ions in the parent crystal lattice, resulting in the expectation of PL spectra Can cause a longer wavelength shift of the emission wavelength. This was due to the formation of strong exciton-phonon coupling between the doped Mn metal ions forming additional Mn-Mn emission centers in the nanocrystals. This is uncommon because ZnSe: Mn nanocrystals have a very low probability of direct formation of the center of Mn-Mn without any interference by neighboring Zn or Se ions. This leads to an exceptionally low quantum yield, as shown in oleic acid capped ZnSe: Mn nanocrystals. On the other hand, the increase of the Mn dopant concentration induced the short wavelength shift of the emission wavelength by forming Zn or Se ion vacancies in the nano lattice during the doping process. Furthermore, an increase in the dopant metal ion concentration of up to 3 to 5% resulted in significant emission quenching. For example, when the concentration of dopant ions in a nanocrystal reaches about 3% for a ZnS nanocrystal doped with a transition metal ion, the dopant metal ion acts as an electron capturing center along with an empty valence orbital, - can induce non-radioactive recombination processes of electrons. In the present invention, it was confirmed that an additional concentration increase of the dopant Mn ion caused a significant decrease in the PL intensity from the oleic acid-capped ZnSe: Mn or complete quenching of the red emission. However, in this system, in the present invention, a pure red emission peak can be obtained without overlapping with the orange emission peak. In addition, red light emission could be obtained from ZnSe: Mn nanocrystals without increasing the Mn ion concentration as above. In certain cases, white light emission has been observed directly from manganese ion doped ZnSe nanocrystals capped with other ligands. However, this phenomenon was not observed from the ZnSe: Mn nanocrystal samples according to the present invention, which exhibited ligand-dependent properties capped on the surface of ZnSe-based nanocrystals.
The PL efficiency for ZnSe-based nanocrystals was determined and calculated in a manner known in the art (Rhys-Williams, AT et al . Analyst , 1983, 108: 1067). Specifically, the relative quantum yield was calculated by comparing the value of 1.0 × 10 -5 M rhodamine 6G ethanol solution with the reference value. The rhodamine 6G has been reported to have an absolute quantum yield of 0.95 (@ 22 ° C) at a wavelength of 566 nm. The excitation wavelength of 420 nm used in the standard solution was determined from the UV / Vis spectrum of ZnSe-based nanocrystals. As a result, the calculated relative PL efficiencies for ZnSe-based nanocrystals were 7.60% for ZnSe, 5.10% for ZnSe: Cu and 0.73% for ZnSe: Mn, respectively. Relative PL efficiencies for red emitting ZnSe: Mn nanocrystals are low for electronic applications. However, obtaining red light emission from ZnSe: Mn nanocrystals has not been reported so far. As reported previously, the most common or typical emitted light from manganese ion doped semiconductor nanocrystals was yellow-orange. ZnSe: Mn nanocrystals have exceptionally low PL efficiency due to the very low probability of direct formation of Mn-Mn centers without interfering with neighboring Zn or Se ions in ZnSe: Mn nanocrystals.
The concentration of dopant metal ions is a very important factor in the optical properties of nanocrystals. The emission color of the oleic acid-capped ZnSe: Cu nanocrystals according to the present invention was found to vary somewhat by the concentration of the dopant ions, but no substantial emission wavelength change was observed from the oleic acid-capped ZnSe: Mn nanocrystals. Instead, a decrease or elimination of emission peak intensity for oleic acid capped ZnSe: Mn nanocrystals in the PL spectrum was observed by dopant concentration change. This is because the initial concentration of the dopant metal ion related to the surface capping ability of the oleic acid ligand induces the formation of the Mn-Mn emission center in the doped ZnSe-based nanocrystals to provide the optimum [Zn] / [Mn] ≪ / RTI > Furthermore, the capping ligand molecules adequately inhibited the formation of additional cationic or anionic valences in the crystal lattice which could have a profound effect on the optical properties of the ZnSe: Mn nanocrystals.
Undoped ZnSe nanocrystals capped with various ligands were synthesized at various reaction temperature conditions (250-320 ℃). From the above experiment, the optimum emission wavelength nearest to the natural blue standard was obtained with the highest PL efficiency from the ZnSe nanocrystals produced at 300 ° C. Therefore, the reaction temperature for forming the parent ZnSe nanocrystals was fixed at 300 ° C. However, when the temperature conditions for forming the parent ZnSe crystal were fixed for Cu and Mn doping into ZnSe nanocrystals, the temperature for the doping process did not substantially affect the emission wavelength of the metal ion doped ZnSe nanocrystals. Instead, intensity reduction (250 ° C) or complete disappearance of emission (150 ° C) was observed in PL spectra obtained from ZnSe: Cu and ZnSe: Mn nanocrystals. This may be because the copper containing the precursor is not sufficiently activated at less than 200 캜 and Cu ions are not sufficiently doped into the ZnSe nanocrystals. From this, it was confirmed that 200 ° C was the proper temperature for doping of Cu and Mn in ZnSe parent nanocrystals. Also, when the primary band gap is fixed by formation of parent ZnSe nanocrystals, the doping concentration may be a factor that has a greater effect on the emission wavelength of the ZnSe-based nanocrystals than the doping temperature.
The CIE chromaticity diagram shown in FIG. 6 shows the chromaticity coordinates of each ZnSe-based nanocrystal. The color coordinates obtained for each nanocrystal were (0.15, 0.16) for ZnSe, (0.22, 0.57) for ZnSe: Cu and (0.62, 0.35) for ZnSe: Mn, Respectively.
Finally, surface capping of oleic acid molecules to ZnSe-based nanocrystals was confirmed by FT-IR and FT-Raman spectroscopy. To remove uncoordinated or unreacted organic or inorganic salt molecules, the centrifuged white solid was washed several times with cold alcohol / water mixed solution. As a result, peaks that could be caused from free oleic acid or other precursor materials were completely removed from the FT-IR and FT-Raman spectra shown. Figures 7 and 8 show the FT-IR and FT-Raman spectra obtained from synthesized ZnSe: Cu nanocrystals superimposed on the spectrum of free oleic acid molecules not bound for direct comparison. The FT-IR spectra obtained from the three different ZnSe-based nanocrystals were nearly identical. This similarity was caused by having a similar reduced mass and binding affinity for Zn-S, Cu-S and Mn-S moieties. At this time, the amount of different metal ions in the crystal lattice was less than 2%. Thus, in order to identify the oleic acid ligand bound to the surface of the nanocrystals, only ZnSe: Cu, which provides the best resolution in the spectrum, is shown. The obtained FT-IR and FT-Raman peak data are all shown in Tables 2 and 3 below. In these tables, the specific vibration mode assignments are based on two references (Fan, Y. et . Et al .) That performed spectral analysis on Fe 3 O 4 nanoparticles capped with oleic acid and free oleic acid molecules not bound by DFT calculations al . , Chin . Phys . Lett . , 2011, 28: 110702; Zhang, L. et al . , Appl. Surface Sci . , 2006, 253: 2611).
In the FT-IR and FT-Raman spectra of ZnSe: Cu nanoparticles, the overall peaks were shifted somewhat from the spectrum of the pure oleic acid molecule except for the microwave region near 3000 cm -1 and the ultra-short wavelength region below 900 cm -1 . In the FT-IR spectrum, the most noticeable peak change between pure oleic acid and bound oleic acid was found at 1710 cm -1 for the C═O elongation band of pure oleic acid to 1535 cm -1 for oleic acid-capped ZnSe: Cu It was remarkably long wave length. A similar phenomenon has been reported for oleic acid bound to Fe 3 O 4 nanoparticles. In this case, the C = O stretching band migrated and was separated into two bands, 1639 cm -1 and 1541 cm -1 , which are characteristic of the asymmetric COO stretching mode. Also, in the FT-Raman spectrum, the C = O elongation band of pure oleic acid at 1660 cm -1 also shifted significantly to 1606 cm -1 in ZnSe: Cu nanocrystals. Collectively, these The results indicate that the carboxylic acid moiety of the oleic acid ligand is attached to the heavier elemental framework, that is, the surface of ZnSe-based nanocrystals. Data analysis of the long wave region of the vibration spectrum has been difficult because the bond between ZnSe and oleic acid molecules limits long wave bending, twisting, and torsional motion. As a result, these bands were shifted considerably in wavelength relative to that of free oleic acid molecules. According to the literature, peaks at 340 nm can be assigned to the transverse and longitudinal optical phonons of the Zn-Se lattice.
In conclusion, the present invention synthesizes three different ZnSe-based nanocrystals that share the same parent crystal but emit light of different wavelengths by the change of the dopant material. Nanocrystals were spectroscopically characterized by UV / Vis and room temperature PL spectroscopy. Additional physical analyzes were performed via XRD, HR-TEM and ICP-AES. PL spectra showed emission peaks at 471 nm for ZnSe, 530 nm for ZnSe: Cu and 665 nm for ZnSe: Mn. These emission peaks are excellent color fidelity and RGB light sources for three-band white LEDs, which were not readily achievable in other systems.
Claims (10)
A second step of preparing a heterogeneous selenium precursor solution by dispersing selenium powder in a mixed solvent of tri-n-butylphosphine or trioctylphosphine oxide and octadecene in a separate reaction flask;
A third step of adding the solution prepared in the second step to the reaction flask in the first step;
The reaction flask in the third step is cooled to 170 to 230 ° C and a dopant solution prepared by dissolving a dopant in a mixed solvent of tri-n-butylphosphine or trioctylphosphine oxide and octadecene is added to the reaction flask Step 4;
A fifth step of heating the reaction flask of the fourth step to 200 to 270 DEG C and maintaining the temperature at the corresponding temperature for 1 hour to 3 hours for aging; And
A sixth step of slowly cooling the reaction flask of the fifth step to 10 to 35 DEG C and adding precipitated ethanol to form a precipitate, and a sixth step of preparing oleic acid-capped ZnSe-based nanocrystals having an emission peak in the visible light region .
Wherein the nanocrystals have a size of 2 to 10 nm diameter.
Wherein the content of the dopant is 0.3 to 1.5 atomic% based on ZnSe.
Wherein the dopant is a copper ion or a manganese ion.
Wherein the dopant releases green light in the range of 500 to 570 nm when the dopant is copper ion.
Wherein the dopant emits red light in the range of 600 to 665 nm when the dopant is a manganese ion.
ZnSe-based nanocrystals comprising oleic acid-capped manganese ion dopants, characterized in that they emit red light in the 600 to 665 nm range.
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