JP2023007431A - organic light sensor - Google Patents

Abstract

To provide an organic light sensor that detects light below an optical bandgap due to each material used in an organic semiconductor layer with high sensitivity.SOLUTION: An organic light sensor (10) includes a lower electrode (first electrode) (11), a hole blocking layer (12), an upper electrode (second electrode) (14), a bulk heterojunction organic semiconductor layer (13) provided between the lower electrode (11) and the upper electrode (14) and containing at least one electron donor molecule and at least one electron acceptor molecule, and a drive circuit (15), and in a state where a forward bias voltage equal to or higher than the open circuit voltage is applied, compared to a state where a forward bias voltage or a reverse bias voltage less than the open circuit voltage is applied, sensitization is performed with light having a wavelength in a first light absorption band resulting from charge transfer between the electron donor molecule and the electron acceptor molecule.SELECTED DRAWING: Figure 1

Description

The present invention relates to an organic photosensor having an active layer of an interpenetrating bulk heterojunction.

An organic photoelectric conversion device is an electronic device having an organic semiconductor layer provided between a pair of electrodes consisting of a cathode and an anode. In the organic photoelectric conversion element, charge carriers (holes and electrons) are generated in the organic semiconductor layer by the energy of light incident on the organic semiconductor layer from the side of the electrode having light transmission properties. The generated holes move toward the anode and the electrons move toward the cathode. Charge carriers that have reached the anode and cathode are extracted outside the organic photoelectric conversion device.

An organic photoelectric conversion element used as a photosensor is used in a state where a voltage is applied, and light incident on the element is converted and detected as a current. Optical sensors are required to detect not only visible light but also near-infrared light having a longer wavelength than visible light. Non-Patent Documents 1 to 3 describe optical sensors that detect near-infrared light.

Siegmund et al., NATURE COMMUNICATIONS 8:15421 (2017) Lan et al., Sci. Adv. 2020; 6: eaaw8065 (2020) Yang et al., Appl. Phys. Lett. 92, 083504 (2008)

However, the optical sensor described in Non-Patent Document 1 needs to reflect light multiple times in order to increase the quantum efficiency. The sensor described in Non-Patent Document 2 has an active layer with a three-layer structure, and therefore is complicated to manufacture. In addition, the optical sensor described in Non-Patent Document 3 is driven at an ultra-high voltage exceeding -100 V and has a large amount of dark current, resulting in insufficient detection performance.

In one embodiment of the present invention, when driven with a reverse bias voltage, it functions as a normal photoelectric conversion element mainly by the photovoltaic effect, and when driven with a forward bias voltage equal to or higher than the open-circuit voltage, it has higher sensitivity and higher sensitivity than when driven with a reverse bias voltage. An object of the present invention is to realize an organic photosensor having a long-wavelength photodetection function.

In order to solve the above problems, an organic photosensor according to an aspect of the present invention is provided with a first electrode, a second electrode, and between the first electrode and the second electrode, and at least one a bulk heterojunction organic semiconductor layer in which an electron donor molecule and at least one electron acceptor molecule are mixed; and one of holes and electrons is emitted from the organic semiconductor layer while a forward bias voltage is applied to the organic semiconductor layer. a barrier layer for suppressing the movement of carriers, and a drive circuit section for applying the forward bias voltage to the first electrode, the organic semiconductor layer, the barrier layer, and the second electrode, and an open-circuit voltage charge transfer between said electron donor molecule and said electron acceptor molecule under conditions of applied forward bias voltage equal to or greater than the open circuit voltage compared to conditions under applied forward bias voltage or reverse bias voltage of less than The light of the wavelength of the first optical absorption band caused by the is sensitized and detected.

According to one aspect of the present invention, a highly sensitive organic photosensor can be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows an example of the organic photosensor which concerns on one form of this invention. It is a figure explaining the structure of the organic-semiconductor layer of the organic photosensor which concerns on one form of this invention. It is a figure explaining the wavelength of the light detected by the organic optical sensor which concerns on one form of this invention. 4 is a graph showing optical absorption bands due to skeletons of acceptor and donor molecules. It is a figure which shows the photocurrent characteristic and photoelectric conversion efficiency of the organic photosensor of an Example. It is a figure which shows the photocurrent characteristic and photoelectric conversion efficiency of the organic photosensor of an Example. It is a figure which shows the photocurrent characteristic and photoelectric conversion efficiency of the organic photosensor of an Example. It is a figure which shows the photoelectric conversion efficiency of the organic photosensor of an Example. It is a figure which shows the photocurrent characteristic and photoelectric conversion efficiency of the organic photosensor of a comparative example. It is a figure which shows the photoelectric conversion efficiency of the organic photosensor of a comparative example. It is a figure which shows the photoelectric conversion efficiency of the organic photosensor of a comparative example. It is a schematic diagram showing an example of an organic photosensor according to another embodiment of the present invention. FIG. 4 is a diagram showing photocurrent characteristics and photoelectric conversion efficiency of an organic photosensor of another example; It is a figure which shows the position detection accuracy of the organic optical sensor of another Example.

An organic photosensor according to one aspect of the present invention includes a first electrode, a second electrode, and between the first and second electrodes, at least one electron donor molecule and at least one electron acceptor molecule. a bulk heterojunction organic semiconductor layer in which molecules are mixed; and a barrier layer that suppresses the movement of either hole or electron carriers from the organic semiconductor layer while a forward bias voltage is applied to the organic semiconductor layer. , a driving circuit unit that applies a forward bias voltage to the first electrode, the organic semiconductor layer, the barrier layer, and the second electrode, and a state in which a forward bias voltage or a reverse bias voltage less than an open circuit voltage is applied. , the light having a wavelength in the first optical absorption band due to charge transfer between the electron donor molecule and the electron acceptor molecule is increased in a state where a forward bias voltage equal to or higher than the open-circuit voltage is applied. Feel and detect. An organic photosensor is a device that consists of an interpenetrating structure of electron donor molecules and electron acceptor molecules. Light detection and narrowband detection are realized.

FIG. 1 is a schematic diagram showing an example of an organic photosensor 10 according to one embodiment of the present invention. As shown in FIG. 1, the organic photosensor 10 has a lower electrode (first electrode) 11, a hole blocking layer (barrier layer) 12, an organic semiconductor layer 13, and an upper electrode (second electrode) 14 laminated in this order. and prepared. The organic photosensor 10 also includes a drive circuit section 15 including a bias voltage generation section 16 that applies a bias voltage, a pulse voltage generation section 17 (power supply or battery) that applies a pulse voltage, and a control circuit 18 . The organic photosensor 10 detects light having a wavelength in the first light absorption band incident from the lower electrode 11 side.

FIG. 2 is a diagram illustrating the structure of the organic semiconductor layer 13 of the organic photosensor 10 according to one embodiment of the present invention. As shown in FIG. 2, in the organic photosensor 10, the organic semiconductor layer 13, which is the active layer, has a bulk heterojunction structure in which electron donor molecules (donor molecules) and electron acceptor molecules (acceptor molecules) are mixed. . In the organic semiconductor layer 13, donor molecules and acceptor molecules form an amorphous interpenetrating structure shown on the left side of FIG.

By including such an organic semiconductor layer 13, the organic photosensor 10 absorbs light not only due to the molecular skeleton of the donor molecule and the acceptor molecule, but also due to intermolecular charge transfer between the donor molecule and the acceptor molecule. is more likely to occur. FIG. 3 is a diagram illustrating wavelengths of light detected by an organic photosensor according to one embodiment of the present invention. As shown in FIG. 3, in the organic photosensor 10, both light absorption due to the molecular skeleton and light absorption due to intermolecular charge transfer occur, and the wavelengths of light absorbed by each are different.

The organic photosensor 10 detects light having a wavelength in the first optical absorption band resulting from intermolecular charge transfer between the donor molecule and the acceptor molecule. That is, the first optical absorption band does not correspond to absorption above the optical bandgap caused by the structure of the donor molecule, nor does it correspond to absorption above the optical bandgap caused by the structure of the acceptor molecule. As shown in FIG. 3, light absorption due to intermolecular charge transfer has a longer wavelength of light than light absorption due to the molecular skeleton.

That is, the first light absorption band resulting from intermolecular charge transfer has a longer wavelength range than the second light absorption band resulting from the molecular skeleton. In the organic photosensor 10, the first light absorption band is a wavelength band below the optical bandgap of the donor molecule and the acceptor molecule, mainly a wavelength band longer than the visible light band, and may be a near-infrared band. Also, the second optical absorption band may be a wavelength band above the optical bandgap of the donor molecule and the acceptor molecule, mainly in the visible light region.

As examples of acceptor and donor molecules, FIG. 4 shows optical absorption bands resulting from the molecular frameworks of PTB7-Th, P3HT, and PCBM. FIG. 4 is a graph showing optical absorption bands due to skeletons of acceptor molecules and donor molecules. As shown in FIG. 4, the light absorption bands absorbed by each of PTB7-Th, P3HT, and PCBM are mainly visible light regions including red, green, and blue regions below 775 nm. Also, the optical bandgaps of PTB7-Th, P3HT, and PCBM are about 1.6 eV, 1.9 eV, and 2.4 eV, respectively. The first optical absorption band can be a wavelength band below these optical bandgaps.

In the organic photosensor 10, in a state in which a forward bias voltage equal to or higher than the open circuit voltage is applied, compared with a state in which a forward bias voltage or a reverse bias voltage lower than the open circuit voltage is applied, the difference between the donor molecule and the acceptor molecule is Light having a wavelength in the first light absorption band caused by charge transfer is sensitized and detected. Here, ``the state in which a forward bias voltage equal to or higher than the open-circuit voltage is applied compared to the state in which the reverse bias voltage is applied'' means that the absolute value can mean a state in which the same forward bias voltage V1 (>open voltage Voc) is applied. In such a state, the organic photosensor 10 has high detection sensitivity to light having a wavelength in the first optical absorption band.

The photoelectric conversion efficiency of the organic semiconductor layer 13 when the organic photosensor 10 is irradiated with the light of the first wavelength in the first optical absorption band in a state in which a forward bias voltage equal to or higher than the open-circuit voltage is applied is approximately the same as that of the donor molecule. It is greater than the photoelectric conversion efficiency of the organic semiconductor layer 13 when irradiated with light of the second wavelength in the second light absorption band caused by the structure or the structure of the acceptor molecule. Also, the photoelectric conversion efficiency is higher when the forward bias is applied than when the reverse bias is applied. Here, photoelectric conversion efficiency means external quantum efficiency IPCE (Incident Photo to Current Efficiency). That is, in the organic photosensor 10, the IPCE peak for light in the first absorption band is larger than the IPCE peak for light in the second absorption band.

FIG. 5 is a diagram showing photocurrent characteristics and photoelectric conversion efficiency in the organic photosensor 10 of Example 1 having a film thickness of 3.5 μm with a weight ratio of PTB7-Th:PCBM=1:4. As shown in FIG. 5, the organic photosensor 10 has an IPCE of 100 when irradiated with light of the first wavelength in the first absorption band (around 800 nm) while a forward bias voltage (+V ₂ ) is applied. % or more. +V ₂ =+5V. In the organic photosensor 10, the IPCE for light of the first wavelength in the first absorption band (near-infrared region) is greater than the IPCE for light of any wavelength in the second absorption band (visible light region). On the other hand, the IPCE is less than 100% when light in the second absorption band is applied while a reverse bias voltage (-5 V) is applied.

FIG. 6 is a diagram showing photocurrent characteristics and photoelectric conversion efficiency in the organic photosensor 10 of Example 2 having a film thickness of 8.3 μm at a weight ratio of PTB7-Th:PCBM=1:2. As shown in FIG. 6, the organic photosensor 10 has an IPCE of 100 when irradiated with light of the first wavelength in the first absorption band (around 800 nm) while a forward bias voltage (+V ₃ ) is applied. % or more. +V ₃ =+8. In addition, when a forward bias voltage (+V ₃ ) is applied and the light of the first wavelength in the first absorption band is irradiated, the IPCE or the photocurrent is the second absorption band (visible light region). greater than the IPCE or photocurrent when illuminated with light of that wavelength. On the other hand, the organic photosensor 10 of Example 2 shown in FIG. 6 exhibits characteristics of narrow-band photodetection in the vicinity of 770 nm with a reverse bias voltage (−V ₄ ) applied, and IPCE is less than 100%. . -V ₄ =-8V.

Thus, the organic photosensor 10 can detect light in the near-infrared region with high accuracy at a low voltage of 10 V or less without multilayering the organic semiconductor layers that function as active layers. In addition, IPCE at a specific wavelength can be increased by using a photo sensor under a forward bias voltage as compared with using it as a photosensor under a reverse bias voltage. Therefore, light can be detected with high accuracy.

The IPCE of the organic semiconductor layer 13 is 100% or more when the organic photosensor 10 is irradiated with light of the first wavelength in the first light absorption band in a state in which a forward bias voltage equal to or higher than the open-circuit voltage is applied. , preferably 200% or more. Then, the photocurrent increases linearly with respect to the forward bias voltage in a state in which a forward bias voltage equal to or higher than the open-circuit voltage is applied. Further, when the organic photosensor 10, which narrowband-detects mainly the first absorption band portion, is applied with a forward bias voltage equal to or higher than the open-circuit voltage, when light of the second wavelength in the second optical absorption band is irradiated, The IPCE of the organic semiconductor layer 13 is less than 100%, preferably less than 10%, more preferably less than 2%.

The organic photosensor 10 is applied with a forward bias voltage equal to or higher than the open circuit voltage, and the photocurrent flowing through the organic semiconductor layer 13 when irradiated with light having a wavelength in the first optical absorption band is of the wavelength of the first light absorption band in a state in which a forward bias voltage or a reverse bias voltage that is larger than the dark current flowing in the organic semiconductor layer 13 and less than the open circuit voltage is applied when the light of the wavelength is not irradiated. It is larger than the photocurrent that flows through the organic semiconductor layer when light is irradiated.

An organic photosensor used as a photodetector is used in a voltage-applied state, and light incident on the device is converted and detected as a current. However, a weak current flows through the organic photosensor even when it is not illuminated with light. This current is known as dark current. In the organic photosensor 10, the photocurrent that flows when light is irradiated is larger than the dark current under a forward bias voltage that causes a forward current to flow, so light can be detected with high accuracy.

(electrode)
At least one of the upper electrode 14 and the lower electrode 11 is made of a transparent or translucent electrode material. Examples of such an electrode material include a conductive metal oxide film and a semitransparent metal thin film. be done. Specifically, indium oxide, zinc oxide, tin oxide, and their composites indium tin oxide (ITO), indium zinc oxide (IZO), conductive materials such as NESA, gold, platinum, silver, and copper. mentioned. Oxide materials such as ITO, IZO, and tin oxide are preferred as transparent or translucent electrode materials. Moreover, as the electrode, a transparent conductive film using an organic compound such as polyaniline and its derivatives, polythiophene and its derivatives as a material may be used.

As long as one electrode is made of a transparent or translucent electrode material, the other electrode may be made of an electrode material with low light transmittance. Electrode materials with low light transmittance include, for example, metals and conductive polymers. Specific examples of electrode materials with low light transmittance include lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, barium, aluminum, scandium, vanadium, zinc, yttrium, indium, cerium, samarium, europium, and terbium. , ytterbium, molybdenum, and alloys of two or more thereof, or one or more of these metals together with gold, silver, platinum, copper, manganese, titanium, cobalt, nickel, tungsten and Alloys with one or more metals selected from the group consisting of tin, graphite, graphite intercalation compounds, polyaniline and its derivatives, polythiophene and its derivatives. As alloys, magnesium-silver alloy, magnesium-indium alloy, magnesium-aluminum alloy, indium-silver alloy, lithium-aluminum alloy, lithium-magnesium alloy, lithium-indium alloy, calcium-aluminum alloy, aluminum-silver alloy, molybdenum - include silver alloys.

In FIG. 1, the lower electrode 11 is a transparent or semi-transparent electrode, and the hole blocking layer 12 is provided between the lower electrode 11 and the organic semiconductor layer 13. However, the upper electrode 14 is a transparent or semi-transparent electrode. A hole blocking layer 12 may be provided between the upper electrode 14 and the organic semiconductor layer 13 .

As a method for forming the electrodes, any conventionally known suitable forming method can be used. Methods for forming the electrodes include, for example, a vacuum deposition method, a sputtering method, an ion plating method, an electron beam deposition method, an inkjet printing method, a screening printing method and a plating method. The method of forming the electrode may include further steps such as patterning the layer structure formed by the above method, surface treatment, and the like.

The film thickness of the upper electrode 14 and the lower electrode 11 is preferably 10 nm or more and 1000 nm or less, more preferably 10 nm or more and 200 nm or less. For example, when the lower electrode 11 is a transparent electrode made of ITO, the film thickness is preferably 10 nm or more and 150 nm or less. For example, when the upper electrode 14 is an electrode made of molybdenum oxide and silver, the film thickness of the molybdenum oxide electrode is 1 nm or more and 100 nm or less, preferably 5 nm or more and 20 nm or less. The film thickness of the silver electrode is 10 nm or more and 1000 nm or less, preferably 15 nm or more and 150 nm or less.

(Hole barrier layer)
The hole blocking layer 12 serves as an electron extraction layer and a hole blocking layer when a reverse bias voltage is applied, and prevents holes from being extracted from the organic semiconductor layer 13 toward the lower electrode 11 side, and extracts electrons from the organic semiconductor layer 13 . The hole blocking layer 12 inhibits the collection of holes toward the lower electrode 11 side when a forward bias is applied, and promotes the extraction of electrons toward the upper electrode 14 side. contribute. An electron transport layer may be further provided between the hole blocking layer 12 and the organic semiconductor layer 13 . Further, instead of providing the hole blocking layer 12, the surface of the lower electrode 11 on the side of the organic semiconductor layer 13 may be subjected to self-assembled monolayer treatment (SAM treatment). For example, 11-aminoundecylphosphonic acid (11-AUPA) can be used for SAM treatment. Also, an interfacial layer may be provided on the SAM-treated layer of the lower electrode 11 using, for example, Cs ₂ CO ₃ .

The hole blocking layer 12 is preferably made of an oxide material such as titanium oxide, zinc oxide and tin oxide. The film thickness of the hole blocking layer 12 is preferably 10 nm or more and 100 nm or less.

As a method for forming the hole blocking layer 12, any conventionally known suitable forming method can be used. For example, an ink containing a material for forming the hole blocking layer 12 can be applied onto the lower electrode 11 by a conventionally known coating method such as a printing method. When forming the hole blocking layer 12 by a printing method, a thin film is formed by a sol-gel method.

(Drive circuit unit 15)
The drive circuit unit 15 applies bias voltage and pulse voltage to the first electrode, the organic semiconductor layer 13, and the second electrode. The drive circuit section 15 includes a bias voltage generator 16 , a pulse voltage generator 17 and a control circuit 18 . The drive circuit unit 15 is a power supply, a battery, and the like. For example, the organic photosensor 10 can be driven in both a state in which a forward bias voltage is applied and a state in which a reverse bias voltage is applied by applying a pulse voltage from the drive circuit unit 15. It can also be used as an element.

(Organic semiconductor layer 13)
Organic semiconductor layer 13 includes at least one electron donor molecule and at least one electron acceptor molecule. The organic semiconductor layer 13 is a bulk heterojunction organic semiconductor layer 13 in which at least one electron donor molecule and at least one electron acceptor molecule are mixed. In the organic semiconductor layer 13, it is preferable that the electron donor molecular region and the electron acceptor molecular region form an amorphous structure. In a part of the organic semiconductor layer 13, the electron donor molecular region and the electron acceptor molecular region may form a crystalline structure, but preferably the amorphous structure portion is larger than the crystalline structure portion.

Here, the amorphous structure formed by the electron donor molecular region and the electron acceptor molecular region means a structure in which the molecular regions are intertwined with each other as shown on the left side of FIG. Intercalated structure), amorphous structure, etc. On the other hand, the crystal structure means a structure in which the molecular regions are regularly aligned as shown on the right side of FIG. 2, and is sometimes called a phase separated structure or a phase separated structure.

Amorphous interpenetrating structures have more contact surfaces between electron donor and electron acceptor molecular regions than do crystalline interpenetrating structures. Since the organic semiconductor layer 13 performs photoelectric conversion by charge transfer between the electron donor molecule and the electron acceptor molecule, it has many amorphous interpenetrating structures with many contact surfaces between the electron donor molecule and the electron acceptor molecule. preferably included.

The organic semiconductor layer 13 is formed by applying an organic semiconductor material in which at least one electron-donating material and at least one electron-accepting material are mixed on the hole blocking layer 12 or the upper electrode 14, and crystalline phase separation progresses. It can be produced by heating at a temperature that does not Such heating temperature may vary depending on the types of the electron-donating material and the electron-accepting material and the film thickness of the organic semiconductor layer 13, but is preferably 50° C. or higher and 200° C. or lower, more preferably 70° C. °C or higher and 100 °C or lower. Thereby, the organic semiconductor layer 13 in which the electron donor molecular region and the electron acceptor molecular region form an amorphous interpenetrating structure can be obtained.

The organic semiconductor layer 13 may contain two or more of the materials described later as the electron-donating material and the electron-accepting material, respectively.

<Electron donating material>
The electron-donating material may be any material that easily donates electrons, and known electron-donating materials can be suitably used. An example of an electron-donating material is an electron-donating (donor) organic compound. Examples of electron-donating materials include polyvinylcarbazole and its derivatives, polysilane and its derivatives, polysiloxane derivatives containing an aromatic amine structure in the side chain or main chain, polyaniline and its derivatives, polythiophene and its derivatives, polypyrrole and its derivatives. , polyphenylene vinylene and its derivatives, polythienylene vinylene and its derivatives, polyfluorene and its derivatives.

The electron-donating material may be a conjugated polymer containing both electron-donating and electron-accepting molecular structures. Examples of conjugated polymers include poly[3-hexylthiophene] (P3HT), poly[3-(4-n-octyl)-phenylthiophene] (POPT), poly[3-10-n-octyl-3 -phenothiazine-vinylenethiophene-co-2,5-thiophene] (PTZV-PT), poly[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b'] dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl] (PTB7), poly[2,6′-4,8 di( 5-ethylhexylthienyl)benzo[1,2-b:3,3-b]dithiophene{3-fluoro-2[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl}](PTB7-Th ), poly[thiophene-2,5-diyl-ortho-[5,6-bis(dodecyloxy)benzo[c][1,2,5]thiadiazole]-4,7-diyl] (PBT-T1), Poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b′]dithiophene)-ortho-4,7(2,1,3 -benzothiadiazole)] (PCPDTBT), poly[5,7-bis(4-decanyl-2-thienyl)-thieno(3,4-b)diathiazolethiophene-2,5] (PDDTT), poly[N- 9′-heptadecanyl-2,7-carbazole-ortho-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (PCDTBT), poly[( 4,4′-bis(2-ethylhexyl)dithieno[3,2-b;2′,3′-d]silole)-2,6-diyl-ortho-(2,1,3-benzothiadiazole)-4 ,7-diyl] (PSBTBT), poly[3-phenylhydrazonethiophene] (PPHT), poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene] (MEH-PPV), poly [2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylene-1,2-ethenylene-2,5-dimethoxy-1,4-phenylene-1,2-ethenylene] (M3EH-PPV) , poly[2-methoxy-5-(3′,7′-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV), poly[9,9-di-octylfluorene-co-bis-N , N- 4-Butylphenyl-bis-N,N-phenyl-1,4-phenylenediamine] (PFB) and derivatives, modifications or mixtures thereof.

Examples of polymer compounds used as electron-donating materials include poly(3-hexylthiophene-2,5-diyl), poly[[2,3,5,6-tetrahydro-2,5-bis( 2-octyldodecyl)-3,6-dioxopyrrolo[3,4-c]pyrrol-1,4-diyl]-2,5-thiophenediylthieno[3,2-b]thiophene-2,5-diyl-2 ,5-thiophenediyl], poly{2,2′-[(2,5-bis(2-hexyldecyl)-3,6-dioxo-2,3,5,6-tetrahydropyrrolo[3,4- c]pyrrol-1,4-diyl)dithiophene]-5,5′-diyl-alt-thiophene-2,5-diyl}, poly[2,5-bis(2-octyldodecyl)pyrrolo[3,4- c]pyrrol-1,4(2H,5H)-dione-3,6-diyl)-alt-(2,2′;5′,2″;5″,2′″-quaterthiophene- 5,5'''-diyl)], poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl] [3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]], poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo [1,2-b;4,5-b′]dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene-)-2- carboxylate-2-6-diyl)], poly[(5,6-difluoro-2,1,3-benzothiadiazol-4,7-diyl)-alt-(3,3'''-di(2- octyldodecyl)-2,2′;5′,2″;5″,2″-quaterthiophene-5,5′″-diyl)], poly[(5,6-difluoro-2 , 1,3-benzothiadiazole-4,7-diyl)-alt-(3,3'''-di(2-nonyltridecyl)-2,2';5',2'';5'',2' ''-Quaterthiophene-5,5'''-diyl)], poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1, 2-b: 4,5-b′]dithiophene))-alt-(5,5-(1′,3′-di-2-thienyl-5′,7′-bis(2-ethylhexyl)benzo[1 ',2'-c:4',5'-c']dithiophene-4,8- dione)], poly[(2,6-(4,8-bis(5-(2-ethylhexylthio)-4-fluorothiophene-2-yl)-benzo[1,2-b:4,5-b ']dithiophene))-alt-(5,5-(1',3'-di-2-thienyl-5',7'-bis(2-ethylhexyl)benzo[1',2'-c:4' ,5′-c′]dithiophene-4,8-dione)], poly[(2,6-(4,8-bis(5-(2-ethylhexyl-3-chloro)thiophen-2-yl)-benzo [1,2-b:4,5-b′]dithiophene))-alt-(5,5-(1′,3′-di-2-thienyl-5′,7′-bis(2-ethylhexyl) benzo[1′,2′-c:4′,5′-c′]dithiophene-4,8-dione)], poly[(2,6-(4,8-bis(5-(2-ethylhexyl- 3-fluoro)thiophen-2-yl)-benzo[1,2-b:4,5-b′]dithiophene))-alt-(5,5-(1′,3′-di-2-thienyl- 5′,7′-bis(2-ethylhexyl)benzo[1′,2′-c:4′,5′-c′]dithiophene-4,8-dione)], poly[[5,7-bis( 2-ethylhexyl)-4,8-dioxo-4H,8H-benzo[1,2-c:4,5-c′]dithiophene-1,3-diyl][3,3′″-bis(2- ethylhexyl)[2,2′:5′,2″:5″,2′″-quaterthiophene]-5,5′″-diyl]], poly[[5,7-bis(2 -ethylhexyl)-4,8-dioxo-4H,8H-benzo[1,2-c:4,5-c′]dithiophene-1,3-diyl][3,3′″-bis(2-ethylhexyl )-3″,4′-difluoro[2,2′:5′,2″:5″,2′″-quaterthiophene]-5,5′″-diyl]], poly{ 2,6′-4,8-di(5-ethylhexylthienyl)benzo[1,2-b;3,4-b]dithiophene-alt-5,5′-dibutyloctyl-3,6-bis(5- thiophen-2-yl)pyrrolo[3,4-c]pyrrol-1,4-dione}, poly[(5,6-dihydro-5-octyl-4,6-dioxo-4H-thieno[3,4- c]pyrrol-1,3-diyl)[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl]], poly [(5,6-dihydro -5-octyl-4,6-dioxo-4H-thieno[3,4-c]pyrrol-1,3-diyl)[4,8-bis[5-(2-ethylhexyl)-2-thienyl]benzo[ 1,2-b: 4,5-b′]dithiophene-2,6-diyl]], poly[N-9′-heptadecanyl-2,7-carbazole-alt-5,5-(4′,7′ -di-2-thienyl-2′,1′,3′-benzothiadiazole)], poly[2,5-bis(2-octyldodecyl)pyrrolo[3,4-c]pyrrolo-1,4(2H, 5H)-dione-3,6-diyl)-alt-(3″,4′-difluoro[2,2′;5′,2″;5″,2′″-quaterthiophene]- 5,5'''-diyl)], poly[[5,6-difluoro-2-(2-hexyldecyl)-2H-benzotriazole-4,7-diyl]-2,5-thiophenediyl [4, 8-bis[5-(tripropylsilyl)-2-thienyl]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl]-2,5-thiophenediyl], poly( 9,9-dioctylfluorene-alt-bithiophene), poly[[2,3-bis(3-octyloxyphenyl)-5,8-quinoxalinediyl]-2,5-thiophenediyl], poly[2-methoxy- 5-(2-ethylhexyloxy)-1,4-phenylenevinylene], poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4- b′]dithiophene)-alt-4,7(2,1,3-benzothiadiazole)], poly[(4,4-bis(2-ethylhexyl)-dithieno[3,2-b:2′,3′ -d]silol)-2,6-diyl-alt-(2,1,3-benzothiadiazole)-4,7-diyl], 2,2′-[(3,3′″,3′″ ',4'-tetraoctyl[2,2':5',2'':5'',2''':5''',2'''-quinquethiophene]-5,5'' ''-diyl)bis[(Z)-methylidine(3-ethyl-4-oxo-5,2-thiazolidinediylidene)]bis-propandinitrile, 7,7'-[4,4-bis( 2-ethylhexyl)-4H-silolo[3,2-b:4,5-b']dithiophene-2,6-diyl]bis[6-fluoro-4-(5'-hexyl-[2,2'- bithiophen]-5-yl)benzo[c][1,2,5]thio diazole], poly[(2,6-(4,8-bis(5-(2-ethylhexyl-3-fluoro)thiophen-2-yl)-benzo[1,2-b:4,5-b' ]dithiophene))-alt-5,5′-(5,8-bis(4-(2-butyloctyl)thiophen-2-yl)dithieno[3′,2′:3,4;2″,3 '': 5,6]benzo[1,2-c][1,2,5]thiadiazole)], poly[(2,6-(4,8-bis(5-(2-ethylhexyl-3-fluoro )thiophen-2-yl)-benzo[1,2-b:4,5-b′]dithiophene))-alt-(5,5-(1′,3′-di-2-thienyl-5′, 7′-bis(2-ethylhexyl)benzo[1′,2′-c:4′,5′-c′]dithiophene-4,8-dione)]-ran-poly[(2,6-(4, 8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1,2-b:4,5-b′]dithiophene))-alt-(2,2-ethyl-3(or4) -carboxylate-thiophene)], poly[(2,6-(4,8-bis(5-(2-ethylhexyl-3-chloro)thiophen-2-yl)-benzo[1,2-b:4, 5-b′]dithiophene))-alt-(2,2-ethyl-3(or4)-carboxylate-thiophene)], poly[(2,6-(4,8-bis(5-(2-ethylhexyl -3-chloro)thiophen-2-yl)-benzo[1,2-b:4,5-b′]dithiophene))-alt-5,5′-(5,8-bis(4-(2- butyloctyl)thiophen-2-yl)dithieno[3′,2′:3,4;2″,3″:5,6]benzo[1,2-c][1,2,5]thiadiazole) ], poly[(2,6-(4,8-bis(5-(2-ethylhexyl-3-chloro)thiophen-2-yl)-benzo[1,2-b:4,5-b′]dithiophene ))-alt-(5,5-(1′,3′-di-2-thienyl-5′,7′-bis(2-ethylhexyl)benzo[1′,2′-c:4′,5′ -c′]dithiophene-4,8-dione)]-ran-poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1,2- b: 4,5-b′]dithiophene))-alt-(2,2-ethyl-3(or4)-carboxylate-thiophene)], poly[(2,6-(4,8-bis(5- (2-ethylhexyl)thiophen-2-yl)-benzo[1,2-b:4,5-b′]dithiophene))-alt-(2,2-ethyl-3(or4)-carboxylate-thiophene) ] and the like.

<Electron-accepting material>
The electron-accepting material may be any material that easily accepts electrons, and known electron-accepting materials can be suitably used. Examples of electron-accepting materials include oxadiazole derivatives, anthraquinodimethane and its derivatives, benzoquinone and its derivatives, naphthoquinone and its derivatives, anthraquinone and its derivatives, tetracyanoanthraquinodimethane and its derivatives, fluorenone derivatives, diphenyl Dicyanoethylene and its derivatives, diphenoquinone derivatives, metal complexes of 8-hydroxyquinoline and its derivatives, fullerenes such as C60 fullerene and its derivatives, and low molecular compounds such as phenanthrene derivatives such as bathocuproine.

Electron-accepting materials include polyvinylcarbazole and its derivatives, polysilane and its derivatives, polysiloxane derivatives having an aromatic amine structure in the side chain or main chain, polyaniline and its derivatives, polythiophene and its derivatives, polypyrrole and its derivatives, It may be a polymer compound such as polyphenylene vinylene and its derivatives, polythienylene vinylene and its derivatives, polyquinoline and its derivatives, polyquinoxaline and its derivatives, and polyfluorene and its derivatives.

Examples of fullerenes include C60 fullerene, C70 fullerene, C76 fullerene, C78 fullerene, and C84 fullerene. Examples of fullerene derivatives include derivatives of these fullerenes. A fullerene derivative means a compound in which at least a part of fullerene is modified. Examples of fullerene derivatives include [6,6]-phenyl-C61 butyric acid methyl ester (C60PCBM), [6,6]-phenyl-C71 butyric acid methyl ester (C70PCBM), [6,6"-phenyl-C85 methyl butyrate ester (C84PCBM), and [6,6]-thienyl-C61 butyric acid methyl ester.

Alternatively, the electron-accepting material may be a non-fullerene material. Examples of non-fullerene materials include 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)- Dithieno[2,3-d:2′,3′-d′]-s-indaceno[1,2-b:5,6-b′]dithiophene, 3,9-bis(2-methylene-((3 -(1,1-dicyanomethylene)-6,7-difluoro)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2′,3′ -d']-s-indaceno[1,2-b:5,6-b']dithiophene, 3,9-bis(2-methylene-((3-(1,1-dicyanomethylene)-6,7 -dichloro)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2′,3′-d′]-s-indaceno[1,2- b: 5,6-b′]dithiophene, 3,9-bis(2-methylene-((3-(1,1-dicyanomethylene)-6/7-methyl)-indanone))-5,5,11 , 11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2′,3′-d′]-s-indaceno[1,2-b:5,6-b′]dithiophene, 3, 9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(5-hexylthienyl)-dithieno[2,3-d:2′ ,3′-d′]-s-indaceno[1,2-b:5,6-b′]dithiophene, 3,9-bis(2-methylene-((3-(1,1-dicyanomethylene)- 6,7-dimethyl)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2′,3′-d′]-s-indaceno[1 ,2-b:5,6-b′]dithiophene, 2,2′-((2Z,2′Z)-((4,4,9,9-tetrahexyl-4,9-dihydro-s-indaceno [1,2-b:5,6-b′]dithiophene-2,7-diyl)bis(methanilylidene))bis(3-oxo-2,3-dihydro-1H-indene-2,1- diylidene)) dimalononitrile, 2,2′-((2Z,2′Z)-((4,4,9,9-tetraoctyl-4,9-dihydro-s-indaceno[1,2-b:5, 6-b′]dithiophene-2,7-diyl)bis(methanylylidene))bis(5, 6-dichloro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile, 2,2′-((2Z,2′Z)-((4,4,9,9 -tetrahexyl-4,9-dihydro-s-indaceno[1,2-b:5,6-b′]dithiophene-2,7-diyl)bis(methanylylidene))bis(5,6-difluoro -3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile, 2,2′-((2Z,2′Z)-((12,13-bis(2-ethylhexyl) -3,9-diundecyl-12,13-dihydro-[1,2,5]thiadiazolo[3,4-e]thieno[2″,3″:4′,5′]thieno[2′,3 ':4,5]pyrrolo[3,2-g]thieno[2',3':4,5]thieno[3,2-b]indole-2,10-diyl)bis(methanylylidene)) Bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile, 2,2′-((2Z,2′Z)-((12,13 -bis(2-butyloctyl)-3,9-diundecyl-12,13-dihydro-[1,2,5]thiadiazolo[3,4-e]thieno[2'',3'':4',5 ']thieno[2',3':4,5]pyrrolo[3,2-g]thieno[2',3':4,5]thieno[3,2-b]indole-2,10-diyl) bis(methanylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile, 2,2′-((2Z,2′ Z)-((12,13-bis(2-decylteradecyl)-3,9-diundecyl-12,13-dihydro-[1,2,5]thiadiazolo[3,4-e]thieno[2″,3 '':4',5']thieno[2',3':4,5]pyrrolo[3,2-g]thieno[2',3':4,5]thieno[3,2-b]indole -2,10-diyl)bis(methanilylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile, 2,2'-[[12,13-bis(2-butyloctyl)-12,13-dihydro-3,9-dinonylbisthieno[2'',3'':4',5']thieno[2',3':4,5]pyrrolo[3,2-e:2',3'-g][2,1,3]benzothiadiazole-2,10-diyl]bis[methylidine(5,6-chloro-3-oxo-1H-indene-2,1(3H)-diylidene)]bis [Propanedinitrile], 2,2′-((2Z,2′Z)-((12,13-bis(2-ethylhexyl)-3,9-diundecyl-12,13-dihydro-[1,2, 5] thiadiazolo[3,4-e]thieno[2″,3″:4′,5′]thieno[2′,3′:4,5]pyrrolo[3,2-g]thieno[2′ ,3′:4,5]thieno[3,2-b]indole-2,10-diyl)bis(methanilylidene))bis(5,6-dichloro-3-oxo-2,3-dihydro- 1H-indene-2,1-diylidene)) dimalononitrile,
2,2′-[[12,13-bis(2-octyldodecyl)-12,13-dihydro-3,9-dinonylbisthieno[2″,3″:4′,5′]thieno[ 2′,3′:4,5]pyrrolo[3,2-e:2′,3′-g][2,1,3]benzothiadiazol-2,10-diyl]bis[methylidine (5 or 6- Bromo-3-oxo-1H-indene-2,1(3H)-diylidene)]]bis[propanedinitrile], 5,5′-[[4,4,9,9-tetrakis(4-hexylphenyl) -4,9-dihydro-s-indaceno[1,2-b:5,6-b′]dithiophene-2,7-diyl]bis(2,1,3-benzothiadiazole-7,4-diylmethylidine )]bis[3-ethyl-2-thioxo-4-thiazolidinone], 2,2′-((2Z,2′Z)-(((4,4-bis(2-ethylhexyl)-4H-cyclopenta[2 , 1-b: 3,4-b′]dithiophene-2,6-diyl)bis(4-(heptan-3-yloxy)thiophene-5,2-diyl))bis(methanylylidene))bis( 5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile, 2,2′-[[4,4,9,9-tetrakis(4-hexylphenyl )-4,9-dihydrothieno[3′,2′:4,5]cyclopenta[1,2-b]thieno[2″,3″:3′,4′]cyclopenta[1′,2 ': 4,5]thieno[2,3-d]thiophene-2,7-diyl]bis[methylidine(3-oxo1H-indene-2,1(3H)-diylidene)]]bis-propanedinitrile, 5,5′-[(9,9-dioctyl-9H-fluorene-2,7-diyl)bis(2,1,3-benzothiadiazole-7,4-diylmethylidin)]bis[3-ethyl-2 -thioxo-4-thiazolidinone], 2,2'-((2Z,2'Z)-(((4,4,9,9-tetrakis(4-hexylphenyl)-4,9-dihydro-sindaceno [ 1,2-b: 5,6-b′]dithiophene-2,7-diyl)bis(4-((2-ethylhexyl)oxy)thiophene-5,2-diyl))bis(methanylylidene)) Bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile, (5Z,5'Z)- 5,5′-((7,7′-(4,4,9,9-tetraoctyl-4,9-dihydro-s-indaceno[1,2-b:5,6-b′]dithiophene-2 ,7-diyl)bis(benzo[c][1,2,5]thiadiazole-7,4-diyl))bis(methanilylidene))bis(3-ethyl-2-thioxothiazolidine-4- on) and the like.

Furthermore, examples of polymer compounds used as electron-accepting materials include poly{[N,N'-bis(2-octyldodecyl)naphthalene-1,4,5,8-bis(dicarboximide)-2,6 -diyl]-alt-5,5′-(2,2′-bithiophene)}, poly[[1,2,3,6,7,8-hexahydro-2,7-bis(2-octyldodecyl)- 1,3,6,8-tetraoxobenzo[lmn][3,8]phenanthroline-4,9-diyl](3,3′-difluoro[2,2′-bithiophene]-5,5′- diyl)], poly{{[N,N′-bis(2-octyldodecyl)naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5′ -(2,2′-bithiophene)}-ran-{[N,N′-bis(2-octyldodecyl)naphthalene-1,4,5,8-bis(dicarboximido)-2,6-diyl] -alt-2,5-thiophene}}, poly[[1,2,3,6,7,8-hexahydro-2,7-bis(2-octyldodecyl)-1,3,6,8-tetraoxo benzo[lmn][3,8]phenanthroline-4,9-diyl]-2,5-thiophenediyl], poly{[N,N'-bis(2-hexyldecyl)naphthalene-1,4,5 ,8-bis(dicarboximide)-2,6-diyl]-alt-5,5′-(2,2′-bithiophene)}, poly{[N,N′-bis(2-hexyldecyl)naphthalene -1,4,5,8-bis(dicarboximido)-2,6-diyl]-alt-2,5-thiophene}, poly(2,5-bis(2-octyldodecyl)-3,6- di(pyridin-2-yl)-pyrrolo[3,4-c]pyrrol-1,4(2H,5H)-dione-alt-2,2′-bithiophene) (DPPDPyBT) and the like.

Some of the materials exemplified as electron-donating materials function as electron-accepting materials, and some of the materials exemplified as electron-accepting materials function as electron-donating materials. there is something

The electron-donating material and the electron-accepting material have a first light absorption band resulting from charge transfer between the electron donor molecule and the electron acceptor molecule in a state in which a forward bias voltage equal to or higher than the open circuit voltage is applied. A material that can detect light of a wavelength may be appropriately selected. The electron-donating material and the electron-accepting material have a first light absorption band resulting from charge transfer between the electron donor molecule and the electron acceptor molecule in a state in which a forward bias voltage equal to or higher than the open circuit voltage is applied. It is preferable to select a combination suitable for detecting light of wavelengths.

As an example, the electron-donating material poly[2,6′-4,8di(5-ethylhexylthienyl)benzo[1,2-b:3,3-b]dithiophene{3-fluoro-2[(2 -ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl}] (PTB7-Th) and the electron-accepting material [6,6]-phenyl-C61 butyric acid methyl ester (C60PCBM) A semiconductor layer 13 is formed. Another example is the electron-donating material poly[3-hexylthiophene-2,5. Diyl] (P3HT) and [6,6]-phenyl-C61 butyric acid methyl ester (C60PCBM), which is an electron-accepting material, are used to form the organic semiconductor layer 13 .

The weight ratio of the electron-donating material and the electron-accepting material forming the organic semiconductor layer 13 is the charge between the electron donor molecule and the electron acceptor molecule under the condition that a forward bias voltage equal to or higher than the open-circuit voltage is applied. Any weight ratio suitable for detecting the light of the wavelength in the first optical absorption band due to migration may be used, and may vary depending on the electron-donating material and the electron-accepting material. As an example, the weight ratio of electron accepting material to electron donating material is 1:1, 1:2, or 1:4.

The film thickness of the organic semiconductor layer 13 is the wavelength of the first light absorption band caused by the charge transfer between the electron donor molecule and the electron acceptor molecule in a state where a forward bias voltage equal to or higher than the open circuit voltage is applied. The film thickness may be suitable for detecting light. As an example, the film thickness of the organic semiconductor layer 13 is the dark current that flows through the organic semiconductor layer 13 when a forward bias voltage equal to or higher than the open-circuit voltage is applied and light having a wavelength in the first light absorption band is not irradiated. However, the film thickness is preferably smaller than the photocurrent flowing through the organic semiconductor layer 13 when light having a wavelength in the first light absorption band is irradiated. The thicker the film, the more difficult it is for the above-described dark current to flow. Therefore, it is more preferable to set the film thickness of the organic semiconductor layer 13 to such a thickness that the above-described dark current does not flow. The preferred film thickness of the organic semiconductor layer 13 may vary depending on the electron-donating material and the electron-accepting material.

The film thickness of the organic semiconductor layer 13 is, for example, 0.3 μm or more and 50 μm or less, preferably 0.5 μm or more and 30 μm or less, and more preferably 1.5 μm or more and 15 μm or less. Since an organic semiconductor material has a high light absorption coefficient of about 10 ⁵ cm ⁻¹ , conventionally, a photoelectric conversion element is generally formed with a thin active layer having a thickness of about several hundred nm. When the film thickness of the organic semiconductor layer 13 is sufficiently thick, the wavelength band portion with a high absorption coefficient is absorbed only near the electrode irradiated with light, and carriers cannot be collected from the electrode, resulting in almost no photocurrent flow. As a result, carriers can be mainly collected from the electrode only in absorption bands with low absorbance near the optical band gaps of the donor and acceptor molecules detected by the organic photosensor 10 . Furthermore, in a state where a forward bias voltage equal to or higher than the open-circuit voltage is applied, the organic photosensor 10 can also detect light mainly in the near-infrared region with a contribution from the absorption part of the first absorption band, and can detect light in a narrow range. Can be banded.

(Manufacturing method of organic photosensor)
The manufacturing method of the organic photosensor 10 according to one embodiment of the present invention is not particularly limited, and the organic photosensor 10 can be manufactured by a forming method suitable for each material selected for manufacturing each component of the organic photosensor 10 . .

In one example of the method of manufacturing the organic photosensor 10, first, the lower electrode 11 is formed on the substrate. An electrode material for forming the lower electrode 11 is used to form a layer structure on the substrate. The layer structure formed on the substrate is patterned by photolithography or the like to form the lower electrode 11 .

Next, a hole blocking layer 12 is formed on the lower electrode 11 by, for example, a printing method. When forming the hole blocking layer 12 by printing, the following sol-gel method can be used. When a zinc oxide (ZnO) thin film is formed as the hole-blocking layer 12, zinc acetate is stirred in 2-ethoxyethanol and aminoethanol for 12 hours or more at 85° C. or more, and is suitable for a sol-gel method. Make a solution. ZnO thin film formation by the sol-gel method is a method described in previous reports (Reference 1: J.Am.Chem.Soc. 137, 6730-6733 (2015), Thin Solid Films 306, 78-85 (1997), etc.) can be referred to.

The solution prepared in this way is applied on the lower electrode 11 to form a thin film, and the hole blocking layer 12 is formed by heating for 10 minutes or more at a heating temperature range of 100° C. or higher and 300° C. or lower, for example. Form. For example, when forming a ZnO thin film, a ZnO solution is applied onto the lower electrode 11 and heated at 200° C. for 30 minutes.

The hole blocking layer 12 may optionally be surface treated to form an ultra-thin interfacial layer. For example, a ZnO thin film formed by a sol-gel method contains poly[(9,9-di(3,3′-N,N′-trimethylammonium)propylfluorenyl-2 ,7-diyl)-alt-co-(9,9-diotylfluorenyl-2,7-diyl)]diiodide (PFN) solution may be used to form a thin film by spin coating. Thereby, deactivation of carriers in the hole blocking layer 12 can be suppressed. The film thickness of such an interface layer is preferably 5 nm or less.

Next, an organic semiconductor layer is formed on the hole blocking layer 12 . As an organic semiconductor material, an organic semiconductor layer is formed using a mixed solution in which an electron donating material and an electron accepting material are mixed in an appropriate weight ratio. Such a mixed solution is applied onto the hole blocking layer 12 to form a film under conditions that do not promote the formation of a crystalline phase-separated structure.

For example, a mixed solution of P3HT or PTB7-Th and PCBM is heated and applied by spin casting. The applied solution is heat-treated under an inert gas at a heating temperature at which the phase separation structure does not proceed. For example, after the applied solution is dried for 30 minutes or longer, it is heat-treated at 85° C. for 12 hours or longer in a nitrogen atmosphere.

An upper electrode 14 is formed on the formed organic semiconductor layer. For example, the upper electrode 14 is formed by vacuum-depositing a metal material. Moreover, it is also possible to form the upper electrode 14 by a printing method by using an oxide nanoparticle solution or a nanoparticle silver solution of the electrode material.

(Other examples of organic photosensors)
An organic photosensor according to another aspect of the invention is described below. For convenience of explanation, members having the same functions as the members explained for the organic photosensor 10 are denoted by the same reference numerals, and the explanation thereof will not be repeated.

An organic photosensor according to another aspect of the present invention further comprises a resistive layer provided between the first electrode and the barrier layer, the second electrode and the resistive layer being transparent or translucent, and the first electrode being , includes at least one pair of electrodes spaced apart from each other. Here, "transparent" or "translucent" means that light having wavelengths in the first light absorption band and the second light absorption band is transmitted. The second electrode and the resistance layer have optical transparency to transmit light having wavelengths in the first optical absorption band and the second optical absorption band.

FIG. 12 is a schematic diagram showing an example of an organic photosensor 20 according to another embodiment of the invention. In FIG. 12, a cross-sectional view 1001 is a vertical cross-sectional view of the upper electrode 14, and a bottom view 1002 is a view of the organic photosensor 20 viewed from the lower electrode 21 side.

As shown in a cross-sectional view 1001, the organic photosensor 20 includes a lower electrode 21, a resistance layer 22, a hole blocking layer 12, an organic semiconductor layer 13, and an upper electrode 14 which are stacked in this order. As shown in bottom view 1002, bottom electrode 21 includes a pair of electrodes spaced apart from each other. The upper electrode 14, resistive layer 22 and lower electrode 21 are transparent or translucent. Note that the lower electrode 21 does not have to transmit light. If the resistive layer 22 is transparent or translucent, light incident from the bottom side of the organic photosensor 20 reaches the organic semiconductor layer 13 .

The organic photosensor 20 also includes a drive circuit section 15 including a bias voltage generation section 16 that applies a bias voltage, a pulse voltage generation section 17 that applies a pulse voltage, and a control circuit 18 . Two driving circuit units 15 are provided so as to apply a voltage between each of the pair of lower electrodes 21 and the upper electrode 14 . Furthermore, the organic photosensor 20 includes a current measuring section 23 that measures a photocurrent that flows when light is incident on the organic photosensor 20 . Two current measurement units 23 are provided so as to measure the divided photocurrent for each of the pair of lower electrodes 21 .

The organic photosensor 20 may be a position sensitive detector (PSD) that detects the incident position of light incident from the upper electrode 14 or lower electrode 21 side. When light is incident from the side of the upper electrode 14 or the lower electrode 21, electric charges proportional to the amount of light are generated at the incident position and reach the resistive layer 22 as photocurrent. This photocurrent is divided inversely proportional to the distance to each of the pair of bottom electrodes. The organic photosensor 20 measures the divided photocurrent values in the current measuring unit 23 and calculates the incident position of the light based on the ratio of the photocurrent values. As described above, the current measurement unit 23 measures the current value when the light is incident from the upper electrode 14 or the lower electrode 21 side using the organic photosensor 20, whereby the incident position of the light can be calculated. .

An example of a method of calculating the incident position of light using the organic photosensor 20 is shown below. As shown in FIG. 12, when the distance from the incident position y of light incident from the upper electrode 14 or the lower electrode 21 side to one of the lower electrodes 21 is x, and the distance between the pair of lower electrodes 21 is L, , the distance x can be calculated by the following equation (1).

In equation ( ₁ ), I1 is the current value of the photocurrent extracted from the lower electrode 21 on the left side in FIG. 12, and _I2 is the current value of the photocurrent extracted from the lower electrode 21 on the right side in FIG. value.

Further, since the organic photosensor 20 includes the organic semiconductor layer 13, it is possible to detect the position of light using wavelength selectivity in light absorption. That is, the organic photosensor 20 detects light of a wavelength in the first light absorption band incident from the upper electrode 14 side, and detects second light having a wavelength shorter than the first light absorption band incident from the lower electrode 21 side. Detects light in the absorption band. As a result, the organic photosensor 20 can detect the incident position of near-infrared light incident from the upper electrode 14 side and the incident position of visible light incident from the lower electrode 21 side. .

<Electrode>
The upper electrode 14 and the lower electrode 21 are made of a transparent or translucent electrode material and have optical transparency. Such an electrode material is the same as the transparent or translucent electrode material described for the organic photosensor 10 , and the electrode formation method, film thickness, etc. are also the same as those described for the organic photosensor 10 . The upper electrode 14 and the lower electrode 21 may be metal electrodes composed of a thin metal layer as long as they have a predetermined light transmittance.

At least one pair of lower electrodes 21 may be provided at positions separated from each other, and two or more pairs may be provided. As an example, if two pairs of lower electrodes 21 are provided, two-dimensional position detection is possible.

<Resistive layer>
A resistive layer 22 is formed on the substrate on which the lower electrode 21 is arranged. The surface resistivity of the resistive layer 22 is preferably 5 Ω/sq or more and 50 MΩ/sq or less, more preferably 100 Ω/sq or more and 10 MΩ/sq or less. An example of a material forming such a resistance layer 22 is zinc oxide. The resistive layer 22 may be formed of a material and film thickness that satisfy the surface resistivity.

The present invention is not limited to the above-described embodiments, but can be modified in various ways within the scope of the claims, and can be obtained by appropriately combining technical means disclosed in different embodiments. is also included in the technical scope of the present invention.

EXAMPLES The present invention will be described in more detail below with reference to examples, but the scope of the present invention is not limited by the following examples.

(Measuring method)
Film thickness was measured using a Veeco Dectak ³ ST apparatus. The photoelectric conversion efficiency of the organic photosensor was measured using a xenon lamp light source manufactured by Hamamatsu Photonics Co., Ltd., spectrometers SPG-120S and SPG-120IR manufactured by Shimadzu Corporation, and an optical filter, and the IPCE characteristics in the near-infrared to visible light range were measured. . The photocurrent that flows when the organic photosensor is irradiated with monochromatic light was measured using a micro current meter 6514 manufactured by Keithley and a power supply device R6145 manufactured by Yokogawa Instruments. The absorption spectrum of the material alone was measured with a UV-3100PC spectrophotometer manufactured by Shimadzu Corporation.

[Photodetection sensitivity of organic photosensor]
(Example 1)
The surface of the ITO-attached glass substrate, on which ITO was pattern-formed as an electrode, was washed with an organic solvent, and then washed with UV ozone. Next, a film of zinc oxide was formed as an electron extraction layer and a hole blocking layer. Zinc acetate (manufactured by Sigma-Aldrich) was stirred in 2-ethoxyethanol (manufactured by Sigma-Aldrich) and aminoethanol (manufactured by Sigma-Aldrich) for 12 hours or more at 85° C. or higher to prepare a sol-gel solution. The solution prepared in this way was applied on the ITO film to form a thin film, which was then heated in a heating temperature range of 200° C. for 30 minutes to form a zinc oxide film having a thickness of 30 nm. Next, an interface layer of 5 nm or less was formed on the zinc oxide film by spin coating using a PFN solution.

Next, a solution mixed at a weight ratio of PTB7-Th:PCBM=1:4 was heated and applied onto the interface layer by a spin casting method. After the applied solution was dried for 30 minutes or more, it was heated at 85° C. for 12 hours in a nitrogen atmosphere to form an organic semiconductor layer with a film thickness of 3.5 μm.

Molybdenum oxide and silver were vacuum-deposited on the organic semiconductor layer to form an upper electrode. The film thickness of the molybdenum oxide film was set to 5 nm, and the film thickness of the silver film was set to 100 nm.

Photocurrent-voltage characteristics and -5V and +5V characteristics when the organic photosensor obtained from the PTB7-Th:PCBM=1:4 thick film device was irradiated with light of about 0.9 mW/cm ² and 850 nm. FIG. 5 shows IPCE characteristics when a voltage is applied.

(Example 2)
An organic photosensor was obtained in the same manner as in Example 1, except that the thickness of the organic semiconductor layer of PTB7-Th:PCBM=1:2 was changed to 8.3 μm. Photocurrent-voltage characteristics and voltages of −8 V and +8 V were measured when the obtained organic photosensor was irradiated with light of about 0.9 mW/cm ² at 850 nm or light at about 1.9 mW/cm ² at 768 nm. The applied IPCE characteristics are shown in FIG.

(Example 3)
An organic photosensor was obtained in the same manner as in Example 1, except that the film thickness of the organic semiconductor layer of PTB7-Th:PCBM=1:2 was changed to 1.1 μm. FIG. 7 shows the photocurrent-voltage characteristics when the obtained organic photosensor was irradiated with light of about 0.9 mW/cm ² and 850 nm, and the IPCE characteristics when voltages of −5 V and +1 V were applied and when no bias was applied. shown in

(Example 4)
An organic photosensor was obtained in the same manner as in Example 1, except that the film thickness of the organic semiconductor layer of P3HT:PCBM=1:2 was 3 μm. FIG. 8 shows the IPCE characteristics of the obtained organic photosensor with voltages of −3 V and +3 V applied during light irradiation.

(Comparative example 1)
The film thickness of the organic semiconductor layer of P3HT:PCBM=1:1 was set to 0.2 μm, the heat treatment temperature of the active layer was set to 120° C., and the ITO electrode was formed with 11-AUPA and Cs ₂ CO ₃ to form an interface layer, An organic photosensor was obtained in the same manner as in Example 1, except that it did not have a ZnO barrier layer. FIG. 9 shows the photocurrent-voltage characteristics of the obtained organic photosensor when it was irradiated with light of 5.6 mW/cm ² and 500 nm, and the IPCE characteristics when a voltage of −4 V was applied.

(Comparative example 2)
An organic photosensor was obtained in the same manner as in Example 1, except that the film thickness of the organic semiconductor layer of P3HT:PCBM=1:2 was 3 μm, and the heat treatment temperature of the active layer was 120°C. FIG. 10 shows the IPCE characteristics of the obtained organic photosensor when a voltage of −3 V and +3 V is applied when light is irradiated.

(Comparative Example 3)
The film thickness of the organic semiconductor layer of PTB7-Th:PCBM=1:4 is set to 3.5 μm, and the interface layer is formed by using 11-AUPA and Cs ₂ CO ₃ as the ITO electrode without using the hole blocking layer ZnO, An organic photosensor was obtained in the same manner as in Example 1, except that it did not have a ZnO barrier layer. FIG. 11 shows the IPCE characteristics of the obtained organic photosensor with application of voltages of −5 V and +4 V when light is irradiated.

(result)
As shown in FIGS. 5 and 6, almost no dark current flows in the organic photosensors of Example 1 (thickness of organic semiconductor layer: 3.5 μm) and Example 2 (thickness of organic semiconductor layer: 8.3 μm). , the IPCE for 800 nm light exceeded 100%. In the organic photosensor of Example 1, the photocurrent flowed when irradiated with light in the visible light range having a shorter wavelength than light of 800 nm, but the IPCE for light in the visible light range was lower than the IPCE for light of 800 nm. The IPCE was higher for light absorption due to intermolecular charge transfer than light absorption due to the molecular skeleton of the donor and acceptor molecules.

In Examples 1 and 2, it was shown that light in the near-infrared region can be detected with high accuracy. Moreover, an IPCE of 100% or more was obtained when a forward bias voltage was applied without multilayering the organic semiconductor layer functioning as an active layer. Furthermore, the IPCE at a specific wavelength can be made higher when using a forward bias voltage than when using it as a photosensor under a reverse bias voltage. Therefore, light can be detected with high accuracy.

As shown in FIG. 7, the organic photosensor of Example 3 was able to detect near-infrared light when a forward bias voltage was applied, which could hardly be detected when a reverse bias voltage was applied. Further, it was confirmed that the organic photosensor of Example 3 exhibited solar cell characteristics even when no bias was applied, and had power storage performance. In the organic photosensors of Examples 1 to 3, the current density-voltage characteristics with respect to light irradiation with near-infrared light of 850 nm (the position indicated by the arrow in the figure) shows that the photocurrent is linear with respect to the voltage when a forward bias voltage is applied. It had the characteristic of increasing In the organic photosensor of Example 4, as shown in FIG. 8, it was shown that light in the near-infrared region can be detected with high accuracy even when P3HT is used.

As shown in FIG. 9, the organic photosensor of Comparative Example 1 caused a photocurrent to flow when irradiated with light having a short wavelength of about 500 nm, but hardly detected light having a longer wavelength. It could not be used as an organic photosensor for near-infrared light such as 800 nm. In addition, under a forward bias voltage (larger than the open-circuit voltage) at which a forward current flows, the dark current is large, so it cannot be used as an organic photosensor.

The organic photosensor of Comparative Example 2 was manufactured by raising the heat treatment temperature of the organic semiconductor layer more than that of the organic photosensor of Example 4 to promote a crystalline phase-separated structure. As shown in FIG. 10, the organic photosensor of Comparative Example 2 had significantly lower light detection sensitivity than the organic photosensor of Example 4 when a forward bias voltage was applied.

The organic photosensor of Comparative Example 3 was manufactured as a structure without ZnO as a hole blocking layer. As shown in FIG. 11, the organic photosensor of Comparative Example 3 has lower light detection sensitivity than the organic photosensor of Example 1 when a forward bias voltage is applied, and the light detection sensitivity of the second wavelength band is also lower than that of the organic photosensor of Example 1. was low.

[Position detection by organic light sensor]
An organic optical sensor for position detection was fabricated. A transparent lower electrode ITO having a width of 100 μm was formed at two locations on the glass substrate at intervals of 5 mm. A ZnO:Al thin film was formed on a glass substrate on which ITO was formed by the method described in Reference 1 to form a resistance layer (Reference 1: T. Morimune, H. Kajii, H. Nishimaru, S. Ono , Organic Position-Sensitive Detectors Based on ZnO:Al and CuPc:C60, J. Nanosci. Nanotechnol. Vol.16, No.4, 3426-3430 (2016)). An organic semiconductor layer containing P3HT:PCBM at a weight ratio of 1:1 was formed on the resistance layer to a thickness of 2 μm. A 100 μm wide semi-transparent upper electrode was formed by depositing silver on the organic semiconductor layer. FIG. 13 shows the IPCE characteristics of the organic photosensor thus produced.

As shown in FIG. 13, for light incident from the transparent lower electrode side, light in the second absorption band corresponding to light absorption caused by the molecular skeleton of donor molecules and acceptor molecules contained in the organic semiconductor layer is mainly detected. It was possible. On the other hand, for the light incident from the semitransparent upper electrode Ag side, the first absorption including near-infrared light corresponding to the light absorption caused by the charge transfer between the donor molecules and the acceptor molecules contained in the organic semiconductor layer. The band of light could be selectively detected.

The incident position of light was detected using such an organic photosensor. Photocurrents I1 and _I2 flowing when the organic photosensor was irradiated with red laser light (650 nm) were measured using an electrometer _6517B manufactured by Keithley. With L as the distance between the transparent lower electrodes and x as the distance from one of the electrodes to the incident position of light, the distance x was calculated from the above equation ( ₁ ) based on the ratio of the photocurrents I1 and _I2 . The results are shown in FIG.

As shown in FIG. 14, when incident from the translucent upper electrode side, the detection error was smaller than when incident from the transparent lower electrode side. The linearity error rate of the detection value of the red laser beam incident from the semi-transparent upper electrode side was estimated to be 1.5%, indicating that highly accurate detection is possible.

10, 20 organic photosensor 11, 21 lower electrode (first electrode)
12 hole barrier layer 13 organic semiconductor layer 14 upper electrode (second electrode)
Reference Signs List 15 drive circuit section 16 bias voltage generation section 17 pulse voltage generation section 18 control circuit 22 resistance layer 23 current measurement section

Claims (11)

a first electrode;
a second electrode;
a bulk heterojunction organic semiconductor layer provided between the first electrode and the second electrode and containing at least one electron donor molecule and at least one electron acceptor molecule;
a barrier layer that suppresses the migration of carriers of either holes or electrons from the organic semiconductor layer while a forward bias voltage is applied to the organic semiconductor layer;
a driving circuit unit that applies the forward bias voltage to the first electrode, the organic semiconductor layer, the barrier layer, and the second electrode;
In a state where a forward bias voltage equal to or higher than the open-circuit voltage is applied, compared with a state where a forward bias voltage or a reverse bias voltage lower than the open-circuit voltage is applied, between the electron donor molecule and the electron acceptor molecule An organic photosensor that sensitizes and detects light having a wavelength in a first optical absorption band caused by charge transfer. With the forward bias voltage applied, the photocurrent flowing in the organic semiconductor layer when the light of the wavelength of the first light absorption band is irradiated is obtained by irradiating the light of the wavelength of the first light absorption band. When light having a wavelength in the first light absorption band is applied in a state in which a forward bias voltage or a reverse bias voltage that is larger than the dark current flowing in the organic semiconductor layer when not in use and is less than the open circuit voltage is applied 2. The organic photosensor of claim 1, wherein the photocurrent flowing through the organic semiconductor layer is greater than that of the photocurrent. The first optical absorption band does not correspond to an absorption band above the optical bandgap caused by the structure of the electron donor molecule, but corresponds to an absorption band above the optical bandgap caused by the structure of the electron acceptor molecule. 3. An organic photosensor according to claim 1 or 2, neither corresponding. The photoelectric conversion efficiency of the organic semiconductor layer when the light of the first wavelength in the first light absorption band is irradiated with a forward bias voltage equal to or higher than the open-circuit voltage is applied, the structure of the electron donor molecule or greater than the photoelectric conversion efficiency of the organic semiconductor layer when irradiated with light of a second wavelength in a second optical absorption band equal to or higher than the optical bandgap due to the structure of the electron acceptor molecule, Item 3. The organic photosensor according to Item 1 or 2. 5. The organic photosensor of claim 4, wherein the first optical absorption band has a longer wavelength range than the second optical absorption band. The photoelectric conversion efficiency of the organic semiconductor layer is 100% or more when the light of the first wavelength in the first light absorption band is irradiated in a state in which a forward bias voltage equal to or higher than the open circuit voltage is applied, and the open circuit voltage is 3. The organic photosensor according to claim 1, wherein the photocurrent increases linearly with respect to the forward bias voltage when the above forward bias voltage is applied. The photoelectric conversion efficiency of the organic semiconductor layer when the light of the second wavelength in the second light absorption band is irradiated with a forward bias voltage or a reverse bias voltage less than the open-circuit voltage is applied is less than 100%. 5. The organic photosensor of claim 4, wherein: 3. The organic photosensor according to claim 1, wherein said first light absorption band is a wavelength region longer than a visible light region. the first electrode is a transparent electrode,
3. The organic photosensor of claim 1, comprising a hole blocking layer between the first electrode and the organic semiconductor layer. further comprising a resistive layer provided between the first electrode and the barrier layer;
the second electrode and the resistive layer are transparent or translucent;
wherein the first electrode comprises at least one pair of electrodes spaced apart from each other;
3. The organic photosensor according to claim 1 or 2. detecting the light of the wavelength of the first light absorption band incident from the second electrode side, and the light of the second light absorption band, which is a wavelength region shorter than the first light absorption band incident from the first electrode side; to detect the
11. The organic photosensor of claim 10.

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