JP2014078742A - Organic thin-film solar cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic thin-film solar cell which can be improved in fill factor and photoelectric conversion efficiency.SOLUTION: The organic thin-film solar cell includes an organic photoelectric conversion element 10 having a cathode 13, an anode 12, and a bulk heterojunction layer 14 in which a p-type semiconductor material and an n-type semiconductor material are mixed. At least a layer containing a compound which has at least two partial structures represented by general formula (1) and in which the at least two partial structures are not directly linked together is provided between the cathode 13 and the anode 12.

Description

  The present invention relates to an organic thin film solar cell using an organic photoelectric conversion element, and more particularly to an organic thin film solar cell using a bulk heterojunction type organic photoelectric conversion element.

  Due to the recent rise in fossil energy, a system that can generate electric power directly from natural energy has been demanded. Solar cells using monocrystalline, polycrystalline, or amorphous Si, compound-based solar cells such as GaAs and CIGS, or Dye-sensitized photoelectric conversion elements (Gretzel cells) have been proposed and put into practical use.

  However, the cost of generating electricity with these solar cells is still higher than the price of electricity generated and transmitted using fossil fuels, which has hindered widespread use. In addition, since heavy glass must be used for the substrate, reinforcement work is required at the time of installation, which is one of the causes that increase the power generation cost.

  In this situation, as a solar cell that can achieve a power generation cost lower than that of fossil fuel, an electron donor layer (p-type semiconductor layer) and an electron acceptor layer ( There has been proposed a bulk heterojunction photoelectric conversion element sandwiching a bulk heterojunction layer mixed with an n-type semiconductor layer).

  Since these bulk heterojunction solar cells are formed by a coating process except for the anode and cathode, it is expected that they can be manufactured at high speed and at low cost, and may solve the above-mentioned problem of power generation cost. . Furthermore, unlike the Si solar cells, compound semiconductor solar cells, and dye-sensitized solar cells described above, there is no process at a temperature higher than 160 ° C., so it can be formed on a cheap and lightweight plastic substrate. Is done.

  The photoelectric conversion efficiency is calculated by the product of the short circuit current (Jsc) × the open circuit voltage (Voc) × the fill factor (FF). In order to obtain a higher short circuit current (Jsc), the photoelectric conversion efficiency is high in, for example, an organic electroluminescence element. It has been reported that high photoelectric conversion efficiency can be obtained by using a fluorene structure or silafluorene structure, which is a mother nucleus having solubility and carrier mobility, as a photoelectric conversion material of an organic photoelectric conversion element (non-patent document). 1-3, and patent documents 1 and 2).

  However, in order to obtain higher photoelectric conversion efficiency, it is necessary to improve not only the short-circuit current (Jsc) but also the open-circuit voltage (Voc), but generally the open-circuit voltage of the organic photoelectric conversion element is as low as about 0.6. I stayed in things. In the organic thin-film solar cell having the above-mentioned fluorene structure or silafluorene structure, a relatively high open circuit voltage (Voc) of 0.7 to 1.0 V is obtained, but it is still insufficient.

  If these can be improved further, it is expected that higher photoelectric conversion efficiency can be obtained. In particular, if the narrow band gap of the photoelectric conversion material is advanced in order to use a wider sunlight spectrum, the HOMO level of the photoelectric conversion material becomes shallow, but the open-circuit voltage (Voc) of the organic photoelectric conversion element is It is said to be related to the difference between the HOMO level of the p-type semiconductor material and the LUMO level of the n-type semiconductor material, and satisfies all of the narrow band gap, high carrier mobility, and deep HOMO level. Therefore, a photoelectric conversion material having a high value has been awaited.

  Further, such a compound having a deep HOMO level is expected to be useful as an electron transport layer of an organic electroluminescence device. That is, when used as an electron transport layer of an organic electroluminescence element, the effect of confining excitons in the light-emitting layer is expected due to the deep HOMO level, which improves luminous efficiency, that is, further improves the power efficiency of organic electroluminescent lighting. Be expected.

JP 2008-106239 A JP 2008-106240 A

Adv. Mater. Vol. 15, p988 (2003) J. et al. Am. Chem. Soc. Vol. 128, p8980 (2006) App. Phy. Let. Vol. 92,033307, (2008)

  An object of the present invention is to provide an organic thin-film solar cell having a high fill factor and photoelectric conversion efficiency.

The above object of the present invention can be achieved by the following configurations 1 to 13. Specifically, according to the present invention,
An organic thin-film solar cell comprising an organic photoelectric conversion element having a cathode, an anode, and a bulk heterojunction layer in which a p-type semiconductor material and an n-type semiconductor material are mixed,
A layer containing at least two or more partial structures represented by the following general formula (1) between the cathode and the anode, and containing a compound in which at least two or more of the partial structures are not directly connected to each other There is provided an organic thin film solar cell characterized by comprising:

(In the formula, Q represents a tetravalent atom selected from carbon, silicon, germanium, titanium, and tin. Z ₁ represents a substituted or unsubstituted nitrogen-containing aromatic 6-membered ring, and Z ₂ represents substituted or unsubstituted. R ₁ and R ₂ each independently represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a cycloalkyl group, an aryl group, or a heteroaryl group, respectively. Represents a selected substituent.)

  1. An organic electronic device comprising a compound having a partial structure represented by the following general formula (1).

(In the formula, Q represents a tetravalent atom selected from carbon, silicon, germanium, titanium, and tin. Z ₁ represents a substituted or unsubstituted nitrogen-containing aromatic 6-membered ring, and Z ₂ represents substituted or unsubstituted. R ₁ and R ₂ each independently represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a cycloalkyl group, an aryl group, or a heteroaryl group, respectively. Represents a selected substituent.)

  2. An organic photoelectric conversion element having a cathode, an anode, and a bulk heterojunction layer in which a p-type semiconductor material and an n-type semiconductor material are mixed, and is represented by at least the following general formula (1) between the cathode and the anode. An organic photoelectric conversion element comprising a layer containing a compound having a partial structure.

(In the formula, Q represents a tetravalent atom selected from carbon, silicon, germanium, titanium, and tin. Z ₁ represents a substituted or unsubstituted nitrogen-containing aromatic 6-membered ring, and Z ₂ represents substituted or unsubstituted. R ₁ and R ₂ each independently represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a cycloalkyl group, an aryl group, or a heteroaryl group, respectively. Represents a selected substituent.)

  3. 3. The organic photoelectric conversion device according to 2 above, wherein the layer containing a compound having a partial structure represented by the general formula (1) is the bulk heterojunction layer.

  4). 3. The organic photoelectric conversion according to 2 above, wherein the layer containing the compound having the partial structure represented by the general formula (1) is a layer formed between the bulk heterojunction layer and the cathode. element.

5. 5. The organic photoelectric conversion element according to any one of 2 to 4, wherein the aromatic ring represented by Z ₂ in the general formula (1) is a nitrogen-containing aromatic 6-membered ring.

  6). 6. The compound according to any one of 2 to 5, wherein the compound having a partial structure represented by the general formula (1) is a compound having a partial structure represented by the following general formula (2). Organic photoelectric conversion element.

(In the formula, X _{1 to} X ₆ represent a substituted or unsubstituted carbon atom or a nitrogen atom, and at least _{one of} X _{1 to} X ₆ represents a nitrogen atom. R ₁ , R _2, and Q represent the above general formula. (It is synonymous with R ₁ , R ₂ and Q in (1).)

  7). 7. The organic photoelectric conversion device as described in 6 above, wherein the atom represented by Q in the compound having the partial structure represented by the general formula (2) is a carbon atom.

8). 8. The organic photoelectric conversion device as described in 6 or 7 above, wherein the atom represented by X ₁ in the compound having a partial structure represented by the general formula (2) is a nitrogen atom.

  9. 9. The organic photoelectric conversion device as described in any one of 2 to 8 above, wherein the compound having a partial structure represented by the general formula (1) or (2) is a low molecular compound.

  10. 10. The organic photoelectric device as described in any one of 2 to 9 above, wherein the layer containing the compound having a partial structure represented by the general formula (1) or (2) is produced by a solution coating method. Conversion element.

  11. It consists of the organic photoelectric conversion element of any one of said 2-10, The solar cell characterized by the above-mentioned.

  12 11. The optical sensor array comprising the organic photoelectric conversion elements according to any one of 2 to 10 arranged in an array.

  13. An organic electroluminescence device having an anode, a hole transport layer, a light emitting layer, an electron transport layer, and a cathode, and having a partial structure represented by the following general formula (1) or (2) An organic electroluminescence device comprising the layer.

(In the formula, Q represents a tetravalent atom selected from carbon, silicon, germanium, titanium, and tin. Z ₁ represents a substituted or unsubstituted nitrogen-containing aromatic 6-membered ring, and Z ₂ represents substituted or unsubstituted. R ₁ and R ₂ each independently represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a cycloalkyl group, an aryl group, or a heteroaryl group, respectively. X _{1 to} X ₆ represent a substituted or unsubstituted carbon atom or a nitrogen atom, and at least _{one of} X _{1 to} X ₆ represents a nitrogen atom.

  According to the present invention, it is possible to provide an organic thin-film solar cell including an organic photoelectric conversion element that can achieve high conversion efficiency, has high durability, and can be applied to a coating process that enables inexpensive manufacturing.

It is sectional drawing which shows the solar cell which consists of a bulk hetero junction type organic photoelectric conversion element. It is sectional drawing which shows the solar cell which consists of an organic photoelectric conversion element provided with the photoelectric converting layer of the three-layer structure of p-i-n. It is sectional drawing which shows the solar cell which consists of an organic photoelectric conversion element provided with a tandem-type bulk heterojunction layer. It is a figure which shows the structure of an optical sensor array.

  As a result of diligent investigations on the above problems, the present inventors have found that the layer containing the compound represented by the general formula (1) exists between the bulk heterojunction layer and the cathode. I have found that I can achieve it. Furthermore, the effect appears more remarkably when a layer containing the compound represented by the general formula (2) or (3) is present between the bulk heterojunction layer and the cathode.

  Hereinafter, the present invention will be described in more detail.

(Organic electronics element)
An organic electronic device is a device that obtains electrically useful characteristics from a thin film layer made of an organic material. For example, an organic electroluminescence element that emits light when electricity is supplied, an organic photoelectric conversion element that generates electric power when irradiated with light, and an organic thin film transistor element that can control the amount of current and voltage can be used. In this invention, it can use preferably in an organic electroluminescent element and an organic photoelectric conversion element, especially an organic photoelectric conversion element. Hereinafter, the organic photoelectric conversion element will be described.

(Configuration of organic photoelectric conversion element and solar cell)
FIG. 1 is a cross-sectional view showing an example of a solar cell composed of a bulk heterojunction organic photoelectric conversion element. In FIG. 1, a bulk heterojunction organic photoelectric conversion element 10 has an anode 12, a hole transport layer 17, a bulk heterojunction layer photoelectric conversion section 14, an electron transport layer 18, and a cathode 13 in this order on one surface of a substrate 11. Are stacked.

  The substrate 11 is a member that holds the anode 12, the photoelectric conversion unit 14, and the cathode 13 that are sequentially stacked. In the present embodiment, since light that is photoelectrically converted enters from the substrate 11 side, the substrate 11 can transmit the light that is photoelectrically converted, that is, with respect to the wavelength of the light to be photoelectrically converted. It is a transparent member. As the substrate 11, for example, a glass substrate or a resin substrate is used. The substrate 11 is not essential. For example, the bulk heterojunction type organic photoelectric conversion element 10 may be configured by forming the anode 12 and the cathode 13 on both surfaces of the photoelectric conversion unit 14.

  The photoelectric conversion unit 14 is a layer that converts light energy into electric energy, and includes a bulk heterojunction layer in which a p-type semiconductor material and an n-type semiconductor material are uniformly mixed. The p-type semiconductor material functions relatively as an electron donor (donor), and the n-type semiconductor material functions relatively as an electron acceptor (acceptor). Here, the electron donor and the electron acceptor are “an electron donor in which, when light is absorbed, electrons move from the electron donor to the electron acceptor to form a hole-electron pair (charge separation state)”. And an electron acceptor ”, which does not simply donate or accept electrons like an electrode, but donates or accepts electrons by a photoreaction.

  In FIG. 1, light incident from the anode 12 through the substrate 11 is absorbed by the electron acceptor or electron donor in the bulk heterojunction layer of the photoelectric conversion unit 14, and electrons move from the electron donor to the electron acceptor. A hole-electron pair (charge separation state) is formed. The generated electric charge is caused by an internal electric field, for example, when the work function of the anode 12 and the cathode 13 is different, the electrons pass between the electron acceptors and the holes are electron donors due to the potential difference between the anode 12 and the cathode 13. The photocurrent is detected by passing through different electrodes to different electrodes. For example, when the work function of the anode 12 is larger than that of the cathode 13, electrons are transported to the anode 12 and holes are transported to the cathode 13. If the magnitude of the work function is reversed, electrons and holes are transported in the opposite direction. In addition, the transport direction of electrons and holes can be controlled by applying a potential between the anode 12 and the cathode 13.

  Although not shown in FIG. 1, other layers such as a hole blocking layer, an electron blocking layer, an electron injection layer, a hole injection layer, or a smoothing layer may be included.

  As a more preferable configuration, the photoelectric conversion unit 14 has a so-called p-i-n three-layer configuration (FIG. 2). A normal bulk heterojunction layer is a 14i layer composed of a mixture of a p-type semiconductor material and an n-type semiconductor layer, but is sandwiched between a 14p layer composed of a single p-type semiconductor material and a 14n layer composed of a single n-type semiconductor material. As a result, the rectification of holes and electrons becomes higher, loss due to recombination of charge-separated holes and electrons is reduced, and higher photoelectric conversion efficiency can be obtained.

  Furthermore, it is good also as a tandem-type structure which laminated | stacked such a photoelectric conversion element for the purpose of the improvement of sunlight utilization factor (photoelectric conversion efficiency). FIG. 3 is a cross-sectional view showing a solar cell composed of an organic photoelectric conversion element including a tandem bulk heterojunction layer. In the case of the tandem configuration, the anode 12 and the first photoelectric conversion unit 14 ′ are sequentially stacked on the substrate 11, the charge recombination layer 15 is stacked, the second photoelectric conversion unit 16, and then the cathode 13 are stacked. By stacking, a tandem structure can be obtained. The second photoelectric conversion unit 16 may be a layer that absorbs the same spectrum as the absorption spectrum of the first photoelectric conversion unit 14 'or may be a layer that absorbs a different spectrum, but is preferably a layer that absorbs a different spectrum. is there. Further, the first photoelectric conversion unit 14 ′ and the second photoelectric conversion unit 16 may both have the above-described three-layer configuration of pin.

  Below, the material which comprises these layers is described.

[P-type semiconductor materials]
In the present invention, it is preferable to use the material of the present invention having the partial structure represented by the general formula (1) as the p-type semiconductor material.

In general formula (1), R ₁ or R ₂ represents a substituent selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a cycloalkyl group, an aryl group, and a heteroaryl group, preferably an alkyl group. And particularly preferably an alkyl group having 6 to 12 carbon atoms.

  In the general formula (1), Q represents a tetravalent atom selected from carbon, silicon, germanium, titanium and tin, and is preferably a carbon atom or a silicon atom from the viewpoint of the electrochemical stability of the resulting compound. In particular, a carbon atom is preferred.

The substituted or unsubstituted nitrogen-containing aromatic 6-membered ring represented by Z ₁ in the general formula (1) preferably has a nitrogen atom number in the range of 1 to 3, but the number of nitrogen atoms is from the stability of the compound. One or two, more preferably one. Further, the position occupied by the nitrogen atom is preferably the α-position or δ-position when the α-position, β-position, γ-position, or δ-position from the side closer to the atom represented by Q in the central 5-membered ring, most preferably The δ position.

  The partial structure represented by the general formula (1) includes a nitrogen-containing six-membered ring structure, and thus has a acceptor (electron acceptor) mother nucleus, a donor (electron donator) mother nucleus, By bonding with a π-electron conjugated system, a material capable of photoelectric conversion up to a long wavelength component included in the sunlight spectrum can be obtained. Such donor mother nucleus generally includes a hetero atom-containing aromatic 5-membered ring, and typically includes pyrrole, furan, silole, thiophene, and selenophene. Further, the bonding position between these and the general formula (1) is preferably the γ position considering that the conjugated system is effectively bonded as much as possible.

  That is, the structure represented by the general formula (2) is more preferable.

The substituted or unsubstituted aromatic hydrocarbon ring or aromatic heterocyclic ring represented by Z ₂ is preferably the above-described substituted or unsubstituted nitrogen-containing aromatic 6-membered ring represented by Z ₁ .

In the general formula (2), X _{1 to} X _{6 each} represent a substituted or unsubstituted carbon atom or nitrogen atom, and a structure in which a nitrogen atom substitutes at any of α-position, γ-position, and δ-position, α-position and γ- The structure in which the nitrogen atom is substituted at each of the positions, or the α-position and the δ-position is preferred.

R _{1 to} R _{4 each} represents a hydrogen atom, a halogen atom, a substituent selected from a substituted or unsubstituted alkyl group, a cycloalkyl group, an aryl group or a heteroaryl group, preferably an alkyl group, particularly preferably. It is a C6-C12 alkyl group.

  Hereinafter, although the specific example of a compound represented by General formula (1) or General formula (2) of this invention is given, this invention is not limited to these.

  In the said compound, n represents 2-100.

  In the present invention, the p-type semiconductor material is preferably a low-molecular compound from the viewpoint that high-purity purification is possible and a thin film having high mobility can be obtained. In the present invention, the low molecular weight compound means a single molecule having no distribution in the molecular weight of the compound. On the other hand, the polymer compound means an aggregate of compounds having a certain molecular weight distribution by reacting a predetermined monomer. However, in practical terms, when defining by molecular weight, a compound having a molecular weight of 3000 or less is preferably classified as a low molecular compound. More preferably, it is 2500 or less, More preferably, it is 2000 or less. On the other hand, a compound having a molecular weight of 3000 or more, more preferably 5000 or more, and further preferably 10,000 or more is classified as a polymer compound. The molecular weight can be measured by gel permeation chromatography (GPC).

  Compounds having such a structure are disclosed in Patent Documents 1 and 2 or Tetrahedron vol. 51, no. 44 (1995), p12127, Journal fuel Praktische Chemie; 322; 6; 1980; 971, and the like.

  Synthesis Example (Synthesis of Compound Example 5)

  2,7-Dibromo-4,5-diazafluorenone was synthesized according to Journal fuer Prachtische Chemie; 322; 6; 1980; The obtained 2,7-dibromo-4,5-diazafluorenone 3.4 g, 2-thiopheneboronic acid 2.8 g, and palladium (0) tetrakis (triphenylphosphine) 400 mg were dissolved in tetrahydrofuran, and 20% sodium carbonate. A few drops of the solution were added and allowed to react for 12 hours under reflux. After completion of the reaction, ethyl acetate and water were added for liquid separation, and the organic layer was extracted. After distilling off the solvent under reduced pressure, the residue was purified by silica gel column chromatography to obtain 1.9 g of 2,7-bis (2-thieno) -4,5-diazafluorenone.

  Next, an equal amount of a 1.6 mol solution of secondary butyl lithium was added to a mixed solution of 2.3 g of 1-bromooctane and tetrahydrofuran (THF) at −78 ° C. under nitrogen, and the mixture was stirred for 30 minutes. -After adding 1.9 g of bis (2-thieno) diazafluorenone, stirred at room temperature day and night, stirred for 1 hour under reflux conditions, then added ethyl acetate and water to perform liquid separation, and extracted the organic layer did. After distilling off the solvent under reduced pressure, the residue was purified by silica gel column chromatography to obtain 2.7 g of 2,7-bis (2-thieno) -9,9-dioctyl-4,5-diazafluorene.

  Then, 2,7-bis (2-thieno) -9,9-dioctyl-4,5-diazafluorene 2 was added to carbon tetrachloride to which 1.7 g of N bromosuccinimide and a catalytic amount of azoisobutyronitrile (AIBN) were added. 0.7 g was dissolved, reacted at 50 ° C. for 5 hours, brominated, and then subjected to liquid separation operation by adding ethyl acetate and water to extract the organic layer. After distilling off the solvent under reduced pressure, the residue was purified by silica gel column chromatography to obtain 2.8 g of 2,7-bis (2- (5-bromothieno)-) 9,9-dioctyl-4,5-diazafluorene. .

  Thereafter, Adv. Mater. 2007, 19, p2295 was synthesized as a reference, and a p-type semiconductor material of Compound Example 5 was synthesized.

  As the p-type semiconductor material of the present invention, other known p-type semiconductor materials (such as condensed polycyclic aromatic low-molecular compounds and conjugated polymers) may be used in combination in addition to the above-described compounds.

  Examples of the condensed polycyclic aromatic low-molecular compound include anthracene, tetracene, pentacene, hexacene, heptacene, chrysene, picene, fluorene, pyrene, peropyrene, perylene, terylene, quaterylene, coronene, ovalene, circumanthracene, bisanthene, zesulene, Compounds such as heptazeslen, pyranthrene, violanthene, isoviolanthene, circobiphenyl, anthradithiophene, porphyrin, copper phthalocyanine, tetrathiafulvalene (TTF) -tetracyanoquinodimethane (TCNQ) complex, bisethylenetetrathiafulvalene (BEDTTTTF ) -Perchloric acid complexes, and derivatives and precursors thereof.

  Examples of the derivative having the above-mentioned condensed polycycle include WO 03/16599 pamphlet, WO 03/28125 pamphlet, US Pat. No. 6,690,029, JP 2004-107216 A. A pentacene derivative having a substituent described in JP-A No. 2003-136964, a pentacene precursor described in US Patent Application Publication No. 2003/136964, and the like; Amer. Chem. Soc. , Vol127. No. 14.4986, J. MoI. Amer. Chem. Soc. , Vol. 123, p9482; Amer. Chem. Soc. , Vol. 130 (2008), no. 9, acene-based compounds substituted with a trialkylsilylethynyl group described in 2706, and porphyrin-based compounds described in JP-A-2008-16834.

  Examples of the conjugated polymer include a polythiophene such as poly-3-hexylthiophene (P3HT) and an oligomer thereof, or a technical group described in Technical Digest of the International PVSEC-17, Fukuoka, Japan, 2007, P1225. Polythiophene, Nature Material, (2006) vol. 5, p328, a polythiophene-thienothiophene copolymer described in WO2008000664, a polythiophene-diketopyrrolopyrrole copolymer described in WO2008000664, a polythiophene-thiazolothiazole copolymer described in Adv Mater, 2007p4160, Nature Mat. vol. 6 (2007), p497 described in PCPDTBT, etc., polypyrrole and its oligomer, polyaniline, polyphenylene and its oligomer, polyphenylene vinylene and its oligomer, polythienylene vinylene and its oligomer, polyacetylene, polydiacetylene, Examples thereof include polymer materials such as σ-conjugated polymers such as polysilane and polygermane.

  In addition, oligomeric materials instead of polymer materials include thiophene hexamer α-sexual thiophene α, ω-dihexyl-α-sexual thiophene, α, ω-dihexyl-α-kinkethiophene, α, ω-bis (3 Oligomers such as -butoxypropyl) -α-sexithiophene can be preferably used.

[N-type semiconductor materials]
The n-type semiconductor material used for the bulk heterojunction layer of the present invention is not particularly limited. Perfluorophthalocyanine), naphthalenetetracarboxylic anhydride, naphthalenetetracarboxylic acid diimide, perylenetetracarboxylic acid anhydride, perylenetetracarboxylic acid diimide and other aromatic carboxylic acid anhydrides and imidized compounds thereof as a skeleton Etc.

  However, fullerene derivatives that can perform charge separation with various p-type semiconductor materials at high speed (˜50 fs) and efficiently are preferable. Fullerene derivatives include fullerene C60, fullerene C70, fullerene C76, fullerene C78, fullerene C84, fullerene C240, fullerene C540, mixed fullerene, fullerene nanotubes, multi-walled nanotubes, single-walled nanotubes, nanohorns (conical), etc. Partially by hydrogen atom, halogen atom, substituted or unsubstituted alkyl group, alkenyl group, alkynyl group, aryl group, heteroaryl group, cycloalkyl group, silyl group, ether group, thioether group, amino group, silyl group, etc. Examples thereof include substituted fullerene derivatives.

  Among them, [6,6] -phenyl C61-butyric acid methyl ester (abbreviation PCBM), [6,6] -phenyl C61-butyric acid-nbutyl ester (PCBnB), [6,6] -phenyl C61-buty Rick acid-isobutyl ester (PCBiB), [6,6] -phenyl C61-butyric acid-n hexyl ester (PCBH), Adv. Mater. , Vol. 20 (2008), p2116, etc., aminated fullerenes such as JP-A 2006-199674, metallocene fullerenes such as JP-A 2008-130889, and cyclics such as US Pat. No. 7,329,709. It is preferable to use a fullerene derivative having a substituent and having improved solubility, such as fullerene having an ether group.

[Method of forming bulk heterojunction layer]
Examples of a method for forming a bulk heterojunction layer in which an electron acceptor and an electron donor are mixed include a vapor deposition method and a coating method (including a casting method and a spin coating method). Among these, the coating method is preferable in order to increase the area of the interface where charges and electrons are separated from each other as described above and to produce a device having high photoelectric conversion efficiency. The coating method is also excellent in production speed.

  After coating, it is preferable to perform heating in order to cause removal of residual solvent, moisture and gas, and improvement of mobility and absorption longwave due to crystallization of the semiconductor material. When annealing is performed at a predetermined temperature during the manufacturing process, a part of the particles is microscopically aggregated or crystallized, and the bulk heterojunction layer can have an appropriate phase separation structure. As a result, the carrier mobility of the bulk heterojunction layer is improved and high efficiency can be obtained.

  The photoelectric conversion part (bulk heterojunction layer) 14 may be composed of a single layer in which the electron acceptor and the electron donor are uniformly mixed, but a plurality of the mixture ratios of the electron acceptor and the electron donor are changed. It may consist of layers. In this case, it can be formed by using a material that can be insolubilized after coating as described above.

[Electron transport layer / hole blocking layer]
Since the organic photoelectric conversion element 10 of the present invention can take out charges generated in the bulk heterojunction layer more efficiently by forming the electron transport layer 18 between the bulk heterojunction layer and the cathode. It is preferable to have this layer.

  As the electron transport layer 18, octaazaporphyrin and a p-type semiconductor perfluoro (perfluoropentacene, perfluorophthalocyanine, etc.) can be used. Similarly, a HOMO of a p-type semiconductor material used for a bulk heterojunction layer. The electron transport layer having a HOMO level deeper than the level is given a hole blocking function having a rectifying effect so that holes generated in the bulk heterojunction layer do not flow to the cathode side. More preferably, a material deeper than the HOMO level of the n-type semiconductor is used as the electron transport layer. Moreover, it is preferable to use a compound with high electron mobility from the characteristic of transporting electrons.

  Such an electron transport layer is also called a hole blocking layer, and it is preferable to use an electron transport layer having such a function. Examples of such materials include phenanthrene compounds such as bathocuproine, n-type semiconductor materials such as naphthalenetetracarboxylic acid anhydride, naphthalenetetracarboxylic acid diimide, perylenetetracarboxylic acid anhydride, perylenetetracarboxylic acid diimide, and titanium oxide. N-type inorganic oxides such as zinc oxide and gallium oxide, and alkali metal compounds such as lithium fluoride, sodium fluoride, and cesium fluoride can be used. A layer made of a single n-type semiconductor material used for the bulk heterojunction layer can also be used.

  In the present invention, the compound represented by the general formula (1) or (2) is suitable as a material having a deep HOMO level and high electron mobility, and is used as an electron transporting layer (also serving as a hole blocking layer). preferable. By using the compound of the present invention as an electron transport layer / hole blocking layer, effects such as an improvement in fill factor and photoelectric conversion efficiency can be obtained.

  In addition, when using the compound of this invention as an electron carrying layer and a hole block layer, it needs to have a HOMO level deeper than the p-type semiconductor material used for a photoelectric converting layer (bulk heterojunction layer). A compound having a shorter conjugate length (small molecular weight) than the structure used for the p-type semiconductor material is preferable.

  Specific examples of the compound represented by the general formula (1) or the general formula (2) of the present invention that are preferable for use as an electron transport layer / hole blocking layer are given below, but the present invention is not limited thereto.

  The means for forming these layers may be either a vacuum deposition method or a solution coating method, but is preferably a solution coating method.

[Hole Transport Layer / Electron Blocking Layer]
In the organic photoelectric conversion element 10 of the present invention, the hole transport layer 17 can be taken out between the bulk heterojunction layer and the anode, and charges generated in the bulk heterojunction layer can be taken out more efficiently. It is preferable to have.

  As a material constituting these layers, for example, as the hole transport layer 17, PEDOT such as trade name BaytronP, polyaniline and its doping material, a cyanide compound described in WO2006 / 019270, etc. Etc. can be used. Note that the hole transport layer having a LUMO level shallower than the LUMO level of the n-type semiconductor material used for the bulk heterojunction layer has a rectifying effect that prevents electrons generated in the bulk heterojunction layer from flowing to the anode side. It has an electronic block function. Such a hole transport layer is also called an electron block layer, and it is preferable to use a hole transport layer having such a function. As such a material, a triarylamine compound described in JP-A-5-271166 or a metal oxide such as molybdenum oxide, nickel oxide, or tungsten oxide can be used. A layer made of a single p-type semiconductor material used for the bulk heterojunction layer can also be used. The means for forming these layers may be either a vacuum deposition method or a solution coating method, but is preferably a solution coating method. Forming the coating film in the lower layer before forming the bulk heterojunction layer is preferable because it has the effect of leveling the coating surface and reduces the influence of leakage and the like.

[Other layers]
For the purpose of improving energy conversion efficiency and improving the lifetime of the element, a structure having various intermediate layers in the element may be employed. Examples of the intermediate layer include a hole block layer, an electron block layer, a hole injection layer, an electron injection layer, an exciton block layer, a UV absorption layer, a light reflection layer, and a wavelength conversion layer.

<Electrode>
The photoelectric conversion element according to the present invention has at least an anode and a cathode. Further, when a tandem configuration is adopted, the tandem configuration can be achieved by using an intermediate electrode. In the present invention, an electrode through which holes mainly flow is called an anode, and an electrode through which electrons mainly flow is called a cathode.

  Further, because of the function of whether or not there is a light-transmitting property, a light-transmitting electrode may be referred to as a transparent electrode, and a non-light-transmitting electrode may be referred to as a counter electrode. Usually, the anode is a translucent transparent electrode, and the cathode is a non-translucent counter electrode.

〔anode〕
The anode of the present invention is preferably an electrode that transmits light of 380 to 800 nm. As the material, for example, transparent conductive metal oxides such as indium tin oxide (ITO), SnO ₂ and ZnO, metal thin films such as gold, silver and platinum, metal nanowires and carbon nanotubes can be used.

  Also, a conductive material selected from the group consisting of polypyrrole, polyaniline, polythiophene, polythienylene vinylene, polyazulene, polyisothianaphthene, polycarbazole, polyacetylene, polyphenylene, polyphenylene vinylene, polyacene, polyphenylacetylene, polydiacetylene and polynaphthalene. A functional polymer can also be used. Further, a plurality of these conductive compounds can be combined to form an anode.

〔cathode〕
The cathode may be a single layer of a conductive material, but in addition to a conductive material, a resin that holds these may be used in combination. As a conductive material for the cathode, a material having a work function (4 eV or less) metal, alloy, electrically conductive compound, and a mixture thereof as an electrode material is used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃ ) Mixtures, indium, lithium / aluminum mixtures, rare earth metals and the like. Among these, from the viewpoint of electron extraction performance and durability against oxidation, etc., a mixture of these metals and a second metal which is a stable metal having a larger work function value than this, for example, a magnesium / silver mixture, magnesium / Aluminum mixtures, magnesium / indium mixtures, aluminum / aluminum oxide (Al ₂ O ₃ ) mixtures, lithium / aluminum mixtures, aluminum and the like are preferred. The cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering. The film thickness is usually selected in the range of 10 nm to 5 μm, preferably 50 to 200 nm.

  If a metal material is used as the conductive material of the cathode, the light coming to the cathode side is reflected and reflected to the first electrode side, and this light can be reused and absorbed again by the photoelectric conversion layer, further improving the photoelectric conversion efficiency. It is preferable.

  Further, the cathode 13 may be a metal (for example, gold, silver, copper, platinum, rhodium, ruthenium, aluminum, magnesium, indium, etc.), a nanoparticle made of carbon, a nanowire, or a nanostructure. A dispersion is preferable because a transparent and highly conductive cathode can be formed by a coating method.

  When the cathode side is made light transmissive, for example, a conductive material suitable for the cathode, such as aluminum and aluminum alloy, silver and silver compound, is formed with a thin film thickness of about 1 to 20 nm, and By providing a film of the conductive light-transmitting material mentioned in the description, a light-transmitting cathode can be obtained.

[Intermediate electrode]
The intermediate electrode material required in the case of the tandem structure as shown in FIG. 3 is preferably a layer using a compound having both transparency and conductivity. Transparent metal oxides such as ITO, AZO, FTO and titanium oxide, very thin metal layers such as Ag, Al and Au, or layers containing nanoparticles / nanowires, conductive polymer materials such as PEDOT: PSS and polyaniline Etc.) can be used.

  In addition, in the hole transport layer and the electron transport layer described above, there is also a combination that works as an intermediate electrode (charge recombination layer) by appropriately combining and laminating, and with such a configuration, the process of forming one layer This is preferable because it can be omitted.

〔substrate〕
When light that is photoelectrically converted enters from the substrate side, the substrate is preferably a member that can transmit the light that is photoelectrically converted, that is, a member that is transparent to the wavelength of the light to be photoelectrically converted. As the substrate, for example, a glass substrate, a resin substrate and the like are preferably mentioned, but it is desirable to use a transparent resin film from the viewpoint of light weight and flexibility. There is no restriction | limiting in particular in the transparent resin film which can be preferably used as a transparent substrate by this invention, The material, a shape, a structure, thickness, etc. can be suitably selected from well-known things. For example, polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) modified polyester, polyethylene (PE) resin film, polypropylene (PP) resin film, polystyrene resin film, polyolefin resins such as cyclic olefin resin Film, vinyl resin film such as polyvinyl chloride, polyvinylidene chloride, polyether ether ketone (PEEK) resin film, polysulfone (PSF) resin film, polyether sulfone (PES) resin film, polycarbonate (PC) resin film, A polyamide resin film, a polyimide resin film, an acrylic resin film, a triacetyl cellulose (TAC) resin film, and the like can be given. If the resin film transmittance of 80% or more at ~800nm), can be preferably applied to a transparent resin film according to the present invention. Among these, from the viewpoint of transparency, heat resistance, ease of handling, strength and cost, it is preferably a biaxially stretched polyethylene terephthalate film, a biaxially stretched polyethylene naphthalate film, a polyethersulfone film, or a polycarbonate film, and biaxially stretched. More preferred are polyethylene terephthalate films and biaxially stretched polyethylene naphthalate films.

  The transparent substrate used in the present invention can be subjected to a surface treatment or an easy adhesion layer in order to ensure the wettability and adhesiveness of the coating solution. A conventionally well-known technique can be used about a surface treatment or an easily bonding layer. For example, the surface treatment includes surface activation treatment such as corona discharge treatment, flame treatment, ultraviolet treatment, high frequency treatment, glow discharge treatment, active plasma treatment, and laser treatment. Examples of the easy adhesion layer include polyester, polyamide, polyurethane, vinyl copolymer, butadiene copolymer, acrylic copolymer, vinylidene copolymer, and epoxy copolymer.

  Further, for the purpose of suppressing the permeation of oxygen and water vapor, a barrier coat layer may be formed in advance on the transparent substrate, or a hard coat layer may be formed in advance on the opposite side to which the transparent conductive layer is transferred. Good.

(Optical function layer)
The organic photoelectric conversion element of the present invention may have various optical functional layers for the purpose of more efficient reception of sunlight. As the optical functional layer, for example, a light condensing layer such as an antireflection film or a microlens array, or a light diffusion layer that can scatter light reflected by the cathode and enter the power generation layer again may be provided. .

  Various known antireflection layers can be provided as the antireflection layer. For example, when the transparent resin film is a biaxially stretched polyethylene terephthalate film, the refractive index of the easy adhesion layer adjacent to the film is 1.57. It is more preferable to set it to ˜1.63 because the interface reflection between the film substrate and the easy adhesion layer can be reduced and the transmittance can be improved. The method for adjusting the refractive index can be carried out by appropriately adjusting the ratio of the oxide sol having a relatively high refractive index such as tin oxide sol or cerium oxide sol and the binder resin. The easy adhesion layer may be a single layer, but may be composed of two or more layers in order to improve adhesion.

  As the condensing layer, for example, it is processed so as to provide a structure on the microlens array on the sunlight receiving side of the support substrate, or the amount of light received from a specific direction is increased by combining with a so-called condensing sheet. Conversely, the incident angle dependency of sunlight can be reduced.

  As an example of the microlens array, quadrangular pyramids having a side of 30 μm and an apex angle of 90 degrees are two-dimensionally arranged on the light extraction side of the substrate. One side is preferably 10 to 100 μm. If it becomes smaller than this, the effect of diffraction will generate | occur | produce and color, and if too large, thickness will become thick and is not preferable.

  Examples of the light scattering layer include various antiglare layers, layers in which nanoparticles or nanowires such as metals or various inorganic oxides are dispersed in a colorless and transparent polymer, and the like.

[Patterning]
The method and process for patterning the electrode, the power generation layer, the hole transport layer, the electron transport layer, and the like according to the present invention are not particularly limited, and known methods can be appropriately applied.

  If it is a soluble material such as a bulk heterojunction layer and a transport layer, only unnecessary portions may be wiped after the entire surface of die coating, dip coating, etc., or direct patterning at the time of coating using a method such as an ink jet method or screen printing. May be.

  In the case of an insoluble material such as an electrode material, the electrode can be patterned by a known method such as mask vapor deposition during vacuum deposition or etching or lift-off. Alternatively, the pattern may be formed by transferring a pattern formed on another substrate.

(Sealing)
Moreover, since the produced organic photoelectric conversion element 10 does not deteriorate with oxygen, moisture, etc. in the environment, it is preferable to seal not only the organic photoelectric conversion element but also an organic electroluminescence element by a known method. For example, a method of sealing a cap made of aluminum or glass by bonding with an adhesive, a plastic film on which a gas barrier layer such as aluminum, silicon oxide, or aluminum oxide is formed and the organic photoelectric conversion element top 10 with an adhesive Method of bonding, spin coating of organic polymer materials with high gas barrier properties (polyvinyl alcohol, etc.), inorganic thin films with high gas barrier properties (silicon oxide, aluminum oxide, etc.) or organic films (parylene, etc.) deposited under vacuum And a method of laminating these in a composite manner.

(Optical sensor array)
Next, an optical sensor array to which the bulk heterojunction type organic photoelectric conversion element 10 described above is applied will be described in detail. The optical sensor array is produced by arranging the photoelectric conversion elements in a fine pixel form by utilizing the fact that the bulk heterojunction type organic photoelectric conversion elements generate a current upon receiving light, and projected onto the optical sensor array. A sensor having an effect of converting an image into an electrical signal.

  FIG. 4 is a diagram showing the configuration of the photosensor array. 4A is a top view, and FIG. 4B is a cross-sectional view taken along the line A-A ′ of FIG.

  In FIG. 4, an optical sensor array 20 is paired with an anode 22 as a lower electrode, a photoelectric conversion unit 24 that converts light energy into electric energy, and an anode 22 on a substrate 21 as a holding member. The cathode 23 is sequentially laminated. The photoelectric conversion unit 24 includes two layers, a photoelectric conversion layer 24b having a bulk heterojunction layer in which a p-type semiconductor material and an n-type semiconductor material are uniformly mixed, and a buffer layer 24a. In the example shown in FIG. 4, six bulk heterojunction type organic photoelectric conversion elements are formed.

  The substrate 21, the anode 22, the photoelectric conversion layer 24b, and the cathode 23 have the same configuration and role as the anode 12, the photoelectric conversion unit 14, and the cathode 13 in the bulk heterojunction photoelectric conversion element 10 described above.

  For example, glass is used for the substrate 21, ITO is used for the anode 22, and aluminum is used for the cathode 23, for example. For example, the BP-1 precursor is used for the p-type semiconductor material of the photoelectric conversion layer 24b, and for example, the exemplified compound 13 is used for the n-type semiconductor material. The buffer layer 24a is made of PEDOT (poly-3,4-ethylenedioxythiophene) -PSS (polystyrene sulfonic acid) conductive polymer (trade name BaytronP, manufactured by Stark Vitec). Such an optical sensor array 20 was manufactured as follows.

  An ITO film was formed on the glass substrate by sputtering and processed into a predetermined pattern shape by photolithography. The thickness of the glass substrate was 0.7 mm, the thickness of the ITO film was 200 nm, and the measurement area (light receiving area) of the ITO film after photolithography was 0.5 mm × 0.5 mm. Next, a PEDOT-PSS film was formed on the glass substrate 21 by spin coating (conditions: rotational speed = 1000 rpm, filter diameter = 1.2 μm). Thereafter, the substrate was heated in an oven at 140 ° C. for 10 minutes and dried. The thickness of the PEDOT-PSS film after drying was 30 nm.

  Next, a 1: 4 mixed film of the compound 5 of the present invention and PCBM was formed on the PEDOT-PSS film by a spin coating method (conditions: rotational speed = 3300 rpm, filter diameter = 0.8 μm). In this spin coating, a mixture obtained by mixing Compound 5 of the present invention and PCBM with a chlorobenzene solvent at 1: 4 and stirring (5 minutes) was used. After forming the mixed film of P3HT and PCBM, annealing was performed by heating in an oven at 180 ° C. for 30 minutes in a nitrogen gas atmosphere. The thickness of the mixed film of Compound 5 and PCBM of the present invention after the annealing treatment was 70 nm.

  Then, using a metal mask having a predetermined pattern opening, 5 nm of the compound 16 of the present invention is deposited as an electron transport layer on the mixed film of the compound 5 and PCBM of the present invention, and then an aluminum layer as a cathode is deposited. It was formed by the method (thickness = 10 nm). Thereafter, 1 μm of PVA (polyvinyl alcohol) was formed by spin coating and baked at 150 ° C. to prepare a passivation layer (not shown). The optical sensor array 20 was produced as described above.

  When this photosensor array 20 was irradiated with light having a predetermined pattern, it was confirmed that the photocurrent was detected only from the cells that were exposed to light and functioned as a photosensor.

《Organic electroluminescence device》
Next, an organic electroluminescence element (also referred to as an organic EL element or an organic electroluminescence element) will be described as a second example of the organic electronics element.

  Although the preferable aspect of the organic electroluminescent element which concerns on this invention is demonstrated, it is not limited to this. The organic electroluminescence element is not particularly limited as long as it has at least one organic layer sandwiched between an anode and a cathode and emits light when a current is passed.

Preferred specific examples of the layer structure of the organic electroluminescent element are shown below.
(I) Anode / light emitting layer / electron transport layer / cathode (ii) Anode / hole transport layer / light emitting layer / electron transport layer / cathode (iii) Anode / hole transport layer / light emitting layer / hole blocking layer / electron Transport layer / cathode (iv) anode / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode buffer layer / cathode (v) anode / anode buffer layer / hole transport layer / light emitting layer / hole Blocking layer / electron transport layer / cathode buffer layer / cathode (vi) anode / hole transport layer / first light emitting layer / electron transport layer / intermediate electrode / hole transport layer / second light emitting layer / electron transport layer / cathode The light emitting layer preferably contains at least two kinds of light emitting materials having different emission colors, and may form a light emitting layer unit composed of a single layer or a plurality of light emitting layers. Further, a tandem configuration (configuration (vi)) in which a plurality of light emitting stacks are stacked may be used. The hole transport layer also includes a hole injection layer and an electron blocking layer.

  As the material for each of the above layers, the same materials as those for the organic photoelectric conversion element described above may be used, and known materials may be used as appropriate.

  However, in particular, when the compound of the present invention is used as an electron transport layer / hole blocking layer, the rectification characteristics of the device are improved as in the case of the organic photoelectric conversion device, and the light emission efficiency can be expected to be improved.

  Below, only the light emitting layer used uniquely for an organic electroluminescent element is demonstrated in detail.

<Light emitting layer>
The light-emitting layer is a layer that emits light by recombination of electrons and holes injected from the electrode, the electron transport layer, or the hole transport layer, and the light-emitting portion is the light-emitting layer even in the light-emitting layer. It may be an interface with an adjacent layer. The light emitting layer is not particularly limited in its configuration as long as the light emitting material included satisfies the above requirements. Moreover, there may be a plurality of layers having the same emission spectrum and emission maximum wavelength.

  It is preferable to have a non-light emitting intermediate layer between each light emitting layer.

  The total thickness of the light emitting layers is preferably in the range of 1 to 100 nm, and more preferably 30 nm or less because a lower driving voltage can be obtained. Note that the sum of the thicknesses of the light emitting layers referred to here is a thickness including the intermediate layers when a non-light emitting intermediate layer exists between the light emitting layers.

  The thickness of each light emitting layer is preferably adjusted to a range of 1 to 50 nm, more preferably adjusted to a range of 1 to 20 nm. There is no particular limitation on the relationship between the film thicknesses of the blue, green and red light emitting layers.

  For the production of the light emitting layer, a light emitting material or a host compound, which will be described later, is formed by forming a film by a known thinning method such as a vacuum deposition method, a spin coating method, a casting method, an LB method, an ink jet method, or the like. it can.

  A plurality of light emitting materials may be mixed in each light emitting layer, or a phosphorescent light emitting material and a fluorescent light emitting material may be mixed and used in the same light emitting layer.

  As a structure of the light emitting layer, it is preferable to contain a host compound and a light emitting material (also referred to as a light emitting dopant compound) and emit light from the light emitting material.

  As the host compound contained in the light emitting layer of the organic electroluminescent element, a compound having a phosphorescence quantum yield of phosphorescence emission at room temperature (25 ° C.) of less than 0.1 is preferable. More preferably, the phosphorescence quantum yield is less than 0.01. Moreover, it is preferable that the volume ratio in the layer is 50% or more among the compounds contained in a light emitting layer.

  As the host compound, known host compounds may be used alone or in combination of two or more. By using a plurality of types of host compounds, it is possible to adjust the movement of charges, and the efficiency of the organic electroluminescent device can be improved. Moreover, it becomes possible to mix different light emission by using multiple types of luminescent material mentioned later, and can thereby obtain arbitrary luminescent colors.

  The host compound may be a conventionally known low molecular compound, a high molecular compound having a repeating unit, or a low molecular compound having a polymerizable group such as a vinyl group or an epoxy group (evaporation polymerizable light emitting host).

  As the known host compound, a compound that has a hole transporting ability and an electron transporting ability, prevents the emission of light from being increased in wavelength, and has a high Tg (glass transition temperature) is preferable. Here, the glass transition point (Tg) is a value obtained by a method based on JIS-K-7121 using DSC (Differential Scanning Colorimetry).

  Next, the light emitting material will be described.

  As the light-emitting material, a fluorescent compound or a phosphorescent material (also referred to as a phosphorescent compound or a phosphorescent compound) is used.

  The phosphorescent material is a compound in which light emission from an excited triplet is observed. Specifically, it is a compound that emits phosphorescence at room temperature (25 ° C.). Although defined as being 01 or more compounds, the preferred phosphorescence quantum yield is 0.1 or more.

  The phosphorescence quantum yield can be measured by the method described in the fourth edition of Experimental Chemistry Course 7, Spectroscopy II, page 398 (1992 edition, Maruzen). The phosphorescence quantum yield in a solution can be measured using various solvents, but when using a phosphorescent material in the present invention, the above phosphorescence quantum yield (0.01 or more) is achieved in any solvent. It only has to be done.

  The phosphorescent light emitting material can be appropriately selected from known materials used for the light emitting layer of the organic electroluminescent device, and preferably a complex system containing a metal of group 8 to 10 in the periodic table of elements. Compounds, more preferably iridium compounds, osmium compounds, platinum compounds (platinum complex compounds), and rare earth complexes, and most preferred are iridium compounds.

  Specific examples of the iridium compound include Organic Letter, vol. 16, 2579-2581 (2001), Inorganic Chemistry, Vol. 30, No. 8, 1685-1687 (1991), J. Am. Am. Chem. Soc. , 123, 4304 (2001), Inorganic Chemistry, Vol. 40, No. 7, 1704-1711 (2001), Inorganic Chemistry, Vol. 41, No. 12, 3055-3066 (2002) , New Journal of Chemistry. 26, 1171 (2002), European Journal of Organic Chemistry, Vol. 4, pages 695-709 (2004), and the like.

  In the present invention, at least one light emitting layer may contain two or more kinds of light emitting materials, and the concentration ratio of the light emitting materials in the light emitting layer may vary in the thickness direction of the light emitting layer.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

<Preparation of Comparative Organic Photoelectric Conversion Element 1>
An indium tin oxide (ITO) transparent conductive film deposited on a glass substrate with a thickness of 110 nm (sheet resistance 13 Ω / □) is patterned to a width of 2 mm using a normal photolithography technique and hydrochloric acid etching, and transparent An electrode was formed.

  The patterned transparent electrode was washed in the order of ultrasonic cleaning with a surfactant and ultrapure water, followed by ultrasonic cleaning with ultrapure water, dried with nitrogen blow, and finally subjected to ultraviolet ozone cleaning. On this transparent substrate, Baytron P4083 (water-soluble polythiophene compound) (manufactured by Starck Vitec), which is a conductive polymer, was spin-coated at a film thickness of 30 nm, and then heat-dried at 140 ° C. in the air for 10 minutes.

  After this, the substrate was brought into the glove box and worked under a nitrogen atmosphere. First, the substrate was heat-treated at 140 ° C. for 3 minutes in a nitrogen atmosphere.

  A liquid prepared by dissolving 0.4% by mass of the following comparative compound 1 as a p-type semiconductor material and 1.6% by mass of the following PCBM (manufactured by Frontier Carbon Co.) as an n-type semiconductor material in chlorobenzene was prepared. While being filtered through a filter, spin coating was performed at 700 rpm for 60 seconds, then at 2200 rpm for 1 second, and dried at room temperature for 30 minutes.

  Comparative compound 1 was synthesized with reference to Non-Patent Document 2.

Next, the substrate on which the organic layer was formed was placed in a vacuum evaporation apparatus. The element was set so that the shadow mask with a width of 2 mm was orthogonal to the transparent electrode, and the inside of the vacuum deposition apparatus was depressurized to 10 ⁻³ Pa or less, and then 0.5 nm of lithium fluoride and 80 nm of Al were evaporated. Finally, the heating for 30 minutes was performed at 120 degreeC, and the comparative organic photoelectric conversion element 1 was obtained. The vapor deposition rate was 2 nm / second for all, and the size was 2 mm square.

  The obtained organic photoelectric conversion element 1 was sealed using an aluminum cap and a UV curable resin (manufactured by Nagase ChemteX Corporation, UV RESIN XNR5570-B1) in a nitrogen atmosphere, and then converted efficiency and a fill factor described below. The results are shown in Table 1.

<Preparation of the organic photoelectric conversion elements 2 to 6 of the present invention>
In the production of the organic photoelectric conversion element 1, the organic material was the same as the comparative organic photoelectric conversion element 1 except that the p-type semiconductor material was changed to the exemplary compound of the present invention described in Table 1 instead of the comparative compound 1. Photoelectric conversion elements 2 to 6 were obtained.

  The obtained organic photoelectric conversion elements 2 to 6 were sealed using an aluminum cap and a UV curable resin under a nitrogen atmosphere, and then evaluated for the following conversion efficiency and curve factor. The results are summarized in Table 1. .

(Evaluation of conversion efficiency and fill factor)
Photoelectric conversion elements prepared above, was irradiated with light having an intensity of 100 mW / cm ² solar simulator (AM1.5G filter), a superposed mask in which the effective area 4.0 mm ² on the light receiving portion, the short circuit current density Jsc ( The four light-receiving portions formed on the same element were measured for mA / cm ² ), open-circuit voltage Voc (V), and fill factor (fill factor) FF, and the average value was obtained. Further, energy conversion efficiency η (%) was obtained from Jsc, Voc, and FF according to Equation 1.

Formula 1 Jsc (mA / cm ² ) × Voc (V) × FF = η (%)

  From Table 1, it can be seen that the use of the p-type semiconductor material of the present invention improves the open-circuit voltage and provides high conversion efficiency.

Example 2
<Preparation of Comparative Organic Photoelectric Conversion Element 11>
Similarly to the production of the comparative organic photoelectric conversion element 1, Baytron P4083 (manufactured by Starck Vitec) was formed and fired at a film thickness of 30 nm.

  After this, the substrate was brought into the glove box and worked under a nitrogen atmosphere. First, the substrate was heat-treated at 140 ° C. for 3 minutes in a nitrogen atmosphere.

  A solution was prepared by dissolving 1.0 mass% of plexcores OS2100 manufactured by Plextronics Co., Ltd. in chlorobenzene and 0.8 mass% of PCBM (manufactured by Frontier Carbon Co.) as the n-type semiconductor material. While being filtered through a 45 μm filter, spin coating was performed at 700 rpm for 60 seconds, then at 2200 rpm for 1 second, and dried at room temperature for 30 minutes.

Next, the substrate on which the organic layer was formed was placed in a vacuum evaporation apparatus. The element was set so that the shadow mask with a width of 2 mm was orthogonal to the transparent electrode, and the inside of the vacuum deposition apparatus was depressurized to 10 ⁻³ Pa or less. Was deposited to 5.0 nm and Al was deposited to 80 nm. Finally, the heating for 30 minutes was performed at 120 degreeC, and the comparative organic photoelectric conversion element 11 was obtained. The vapor deposition rate was 2 nm / second for all, and the size was 2 mm square.

The obtained organic photoelectric conversion element 11 was sealed using an aluminum cap and a UV curable resin (manufactured by Nagase ChemteX Corporation, UV RESIN XNR5570-B1) in a nitrogen atmosphere, and then a solar simulator (AM1.5G). ) Was irradiated at an irradiation intensity of 100 mW / cm ² , voltage-current characteristics were measured, and initial conversion efficiency was measured.

<Preparation of the organic photoelectric conversion elements 12 to 14 of the present invention>
In the production of the organic photoelectric conversion element 11, the same procedure as in the comparative organic photoelectric conversion element 11 was performed except that the electron transport layer / hole blocking layer was changed to the exemplified compound of the present invention described in Table 2 instead of bathocuproine. Thus, organic photoelectric conversion elements 12 to 14 were obtained.

  The above results are summarized in Table 2.

  From Table 2, it can be seen that the use of the electron transport layer / hole blocking layer of the present invention improves the fill factor and provides high conversion efficiency.

DESCRIPTION OF SYMBOLS 10 Bulk heterojunction type organic photoelectric conversion element 11 Substrate 12 Anode 13 Cathode 14 Bulk heterojunction layer (photoelectric conversion part)
14p p layer 14i i layer 14n n layer 14 'first photoelectric conversion part 15 charge recombination layer 16 second photoelectric conversion part 17 hole transport layer 18 electron transport layer 20 photosensor array 21 substrate 22 anode 23 cathode 24 photoelectric Conversion unit 24a Buffer layer 24b Photoelectric conversion layer

Claims (11)

An organic thin-film solar cell comprising an organic photoelectric conversion element having a cathode, an anode, and a bulk heterojunction layer in which a p-type semiconductor material and an n-type semiconductor material are mixed,
A layer containing at least two or more partial structures represented by the following general formula (1) between the cathode and the anode, and containing a compound in which at least two or more of the partial structures are not directly connected to each other An organic thin film solar cell comprising:

(In the formula, Q represents a tetravalent atom selected from carbon, silicon, germanium, titanium, and tin. Z ₁ represents a substituted or unsubstituted nitrogen-containing aromatic 6-membered ring, and Z ₂ represents substituted or unsubstituted. R ₁ and R ₂ each independently represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a cycloalkyl group, an aryl group, or a heteroaryl group, respectively. Represents a selected substituent.)   The organic thin film solar cell according to claim 1, wherein the layer containing the compound having a partial structure represented by the general formula (1) is the bulk heterojunction layer.   The organic thin film according to claim 1, wherein the layer containing the compound having a partial structure represented by the general formula (1) is a layer formed between the bulk heterojunction layer and a cathode. Solar cell. The organic thin-film solar cell according to claim 1, wherein the aromatic ring represented by Z ₂ in the general formula (1) is a nitrogen-containing aromatic six-membered ring. The compound having a partial structure represented by the general formula (1) is a compound having a partial structure represented by the following general formula (2). Organic thin film solar cell.

(In the formula, X _{1 to} X ₆ represent a substituted or unsubstituted carbon atom or a nitrogen atom, and at least _{one of} X _{1 to} X ₆ represents a nitrogen atom. R ₁ , R _2, and Q represent the above general formula. (It is synonymous with R ₁ , R ₂ and Q in (1).)   The organic thin-film solar cell according to claim 5, wherein the atom represented by Q in the compound having the partial structure represented by the general formula (2) is a carbon atom. The organic thin film solar cell according to claim 5 or 6, wherein the atom represented by X ₁ in the compound having a partial structure represented by the general formula (2) is a nitrogen atom.   The organic thin film solar cell according to any one of claims 1 to 7, wherein the compound having a partial structure represented by the general formula (1) or (2) is a low molecular compound.   The organic layer according to any one of claims 1 to 8, wherein the layer containing a compound having a partial structure represented by the general formula (1) or (2) is produced by a solution coating method. Thin film solar cell. The organic thin film solar cell according to claim 1, wherein R ₁ or R ₂ in the general formula (1) or (2) is an aromatic hydrocarbon ring group. The organic thin film solar cell according to claim 10, wherein R ₁ or R ₂ in the general formula (1) or (2) is an aromatic hydrocarbon ring group substituted with an alkyl group or an alkylene group.

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