JP2013225542A - Conjugated polymer compound and organic photoelectric conversion element using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conjugated polymer compound which has high mobility and is capable of exhibiting sufficient photoelectric conversion efficiency in an organic photoelectric conversion element, and to provide an organic photoelectric conversion element using the same.SOLUTION: The conjugated polymer compound has a partial structure represented by general formula 1. An organic photoelectric conversion element 20 includes a first electrode 11, a second electrode 12, and a photoelectric conversion layer 14 which exists between the first electrode 11 and the second electrode 12 and contains an n-type organic semiconductor and a p-type organic semiconductor. The p-type organic semiconductor contains the conjugated polymer compound having the partial structure represented by the general formula 1.

Description

  The present invention relates to a conjugated polymer compound and an organic photoelectric conversion device using the same. More specifically, the present invention relates to a technique for improving the photoelectric conversion efficiency and the like of an organic photoelectric conversion element.

  In recent years, in order to cope with global warming, reduction of carbon dioxide emissions has been strongly desired. In addition, fossil fuels such as oil, coal, and natural gas are expected to be depleted in the near future, and there is an urgent need to secure alternative earth-friendly energy resources. Therefore, development of power generation technology using sunlight, wind power, geothermal energy, nuclear power, and the like has been actively carried out. Among them, solar power generation is particularly attracting attention because of its high safety.

  In solar power generation, light energy is directly converted into electric power using a photoelectric conversion element utilizing the photovoltaic effect. Generally, a photoelectric conversion element has a structure in which a photoelectric conversion layer (light absorption layer) is sandwiched between a pair of electrodes, and light energy is converted into electric energy in the photoelectric conversion layer. The photoelectric conversion element is a silicon-based photoelectric conversion element using single-crystal / polycrystalline / amorphous Si, GaAs, CIGS (copper (Cu), indium (In), depending on the material used for the photoelectric conversion layer and the form of the element. Compound-based photoelectric conversion elements using a compound semiconductor such as gallium (Ga) and selenium (Se)), dye-sensitized photoelectric conversion elements (Gretzel cells), and the like have been proposed and put to practical use.

  However, the power generation cost when these solar cells are used is still higher than the cost when generating and transmitting power using fossil fuels, which hinders the spread of solar power generation. In addition, since heavy glass must be used for the substrate, reinforcement work is required when it is installed on a roof or the like, which has also contributed to the increase in power generation costs.

  As a technique for reducing power generation costs in solar power generation, a mixture of an electron-donating organic compound (p-type organic semiconductor) and an electron-accepting organic compound (n-type organic semiconductor) between a transparent electrode and a counter electrode A bulk heterojunction (BHJ) type photoelectric conversion element is proposed that includes a photoelectric conversion layer. In 2007, a photoelectric conversion efficiency exceeding 5% was reported (Non-Patent Document 1), and further, it is theoretically expected that a photoelectric conversion efficiency of 10% can be achieved (Non-Patent Document 2). ). In order to achieve such high photoelectric conversion efficiency, it is predicted that the LUMO of the p-type organic semiconductor material is required to be −3.9 to −4.0 eV and the band gap is 1.4 to 1.6 eV. ing. These are predictions when the fill factor (FF) and the external quantum efficiency (EQE) can both achieve 0.65.

  Bulk heterojunction organic photoelectric conversion elements are lightweight and flexible, and are expected to be applied to various products. In addition, since the structure is relatively simple and a photoelectric conversion layer can be formed by applying a p-type organic semiconductor and an n-type organic semiconductor, cost reduction can be expected by mass production on a roll-to-roll basis. It is thought to contribute to the early dissemination of More specifically, in the bulk heterojunction organic photoelectric conversion element, the electrodes (anode and cathode), the metal oxide layer constituting the hole transport layer, and the like can be formed by a method other than the coating process (for example, vacuum deposition method). Etc.). On the other hand, other layers can be formed using a coating process. Therefore, it is expected that the production of the bulk heterojunction photoelectric conversion element can be performed at high speed and at low cost, and it is considered that there is a possibility that the above-described problem of power generation cost can be solved. Further, unlike the production of conventional silicon-based photoelectric conversion elements, compound-based photoelectric conversion elements, dye-sensitized photoelectric conversion elements, etc., it does not necessarily involve a manufacturing process at a temperature higher than 160 ° C. It is expected that it can be formed on a lightweight plastic substrate.

  However, the organic photoelectric conversion element is still not sufficient in photoelectric conversion efficiency and durability against heat and light as compared with other types of photoelectric conversion elements. Accordingly, various improvements have been made in order to improve photoelectric conversion efficiency and durability. In particular, for the purpose of improving durability, for example, each layer is laminated in the reverse order of a normal organic photoelectric conversion element, electrons are taken out from the transparent electrode side, and holes are taken from the stable metal electrode side having a deep work function. A so-called reverse layer type organic photoelectric conversion element to be taken out has been proposed (Patent Document 1). Such a reverse layer type organic photoelectric conversion element has a configuration in which a hole transport layer composed of a conductive polymer having inferior optical transparency exists between a counter electrode (anode) and a photoelectric conversion layer. In general, the counter electrode (anode) is made of a metal material, but the light reflected by the counter electrode cannot be efficiently reused in the photoelectric conversion layer due to the presence of the hole transport layer having low light transmittance. Therefore, the reverse layer type is a disadvantageous configuration from the viewpoint of utilization of light (Non-Patent Document 3). Therefore, in order to obtain sufficient photoelectric conversion efficiency in the reverse layer type, it is generally necessary to take measures such as increasing the film thickness of the photoelectric conversion layer compared to the normal layer type. Material is required. In particular, in order to achieve the aforementioned fill factor (FF)> 0.65 and external quantum efficiency (EQE)> 0.65, a high mobility organic semiconductor material is required.

  In response to such a problem, Patent Document 2 proposes a polymer having a diketopyrrolopyrrole moiety as an organic semiconductor material having good charge transfer characteristics and an appropriate energy level.

JP 2009-146981 A International Publication No. 2011/119446

A. Heeger et al. , Nature Mat. , Vol. 6 (2007), p497 Christoph J. et al. Brabec et al. , Adv. Mater. 2006, 18, p789 J. et al. Peet et al. , Appl. Phys. Lett. , 98, 043301 (2011)

However, the polymer having a diketopyrrolopyrrole structure described in Patent Document 2 still has a mobility of 1 × 10 ⁻⁴ because an alkyl group bonded to a nitrogen atom causes a steric hindrance to twist the polymer main chain. It was difficult to achieve high mobility and high photoelectric conversion efficiency while staying on the order of cm ² · V ⁻¹ · s ⁻¹ .

  Accordingly, the present invention provides a conjugated polymer compound that has high mobility and can exhibit sufficient photoelectric conversion efficiency in an organic photoelectric conversion element, and an organic photoelectric conversion element using the same (especially advantageous in terms of durability). Another object of the present invention is to provide an organic photoelectric conversion element that can exhibit excellent photoelectric conversion efficiency even in a reverse layer configuration.

  In order to solve the above problems, the present inventors have conducted intensive research. And by using a novel conjugated polymer compound containing thienothiophene diylidene structure with high mobility and low steric hindrance, both high mobility and appropriate energy level can be achieved, and sufficient photoelectric conversion efficiency is demonstrated. It was found that an organic photoelectric conversion element capable of being provided could be provided, and the present invention was completed.

  That is, according to one aspect of the present invention, an n-type organic semiconductor and a p-type organic semiconductor that exist between the first electrode, the second electrode, and the first electrode and the second electrode are provided. An organic photoelectric conversion element is provided, wherein the p-type organic semiconductor includes a conjugated polymer compound having a partial structure represented by the following general formula 1.

  According to another embodiment of the present invention, a conjugated polymer compound having a partial structure represented by the following general formula 1 is provided.

In the formula, X ¹ and X ² each independently represent ═O or ═CR ¹ R ² ,
R ¹ and R ² each independently represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 24 carbon atoms, a fluorinated alkyl group having 1 to 24 carbon atoms, or 3 carbon atoms. -20 cycloalkyl group, fluorinated cycloalkyl group having 3 to 20 carbon atoms, alkoxy group having 1 to 24 carbon atoms, fluorinated alkoxy group having 1 to 24 carbon atoms, alkylthio having 1 to 24 carbon atoms Group, a fluorinated alkylthio group having 1 to 24 carbon atoms, an aryl group having 6 to 30 carbon atoms, a fluorinated aryl group having 6 to 30 carbon atoms, a heteroaryl group having 1 to 20 carbon atoms, or a carbon atom Represents a fluorinated heteroaryl group of number 1 to 20, or a cyano group,
D ¹ and D ² each independently represent a donor unit containing a heteroaromatic ring,
p represents an integer of 1 to 4,
q represents the integer of 1-4.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the conjugated polymer compound which can make high mobility and an appropriate energy level compatible in an organic photoelectric conversion element. And the organic photoelectric conversion element using the said conjugated polymer compound can exhibit sufficient photoelectric conversion efficiency. Furthermore, the conjugated polymer compound has good durability, and an organic photoelectric conversion element having excellent durability can be obtained by using this conjugated polymer compound.

It is the cross-sectional schematic which represented typically the normal layer type organic photoelectric conversion element based on one Embodiment of this invention. It is the cross-sectional schematic which represented typically the reverse layer type organic photoelectric conversion element based on other one Embodiment of this invention. It is the cross-sectional schematic which represented typically the organic photoelectric conversion element provided with the tandem-type photoelectric conversion layer based on other one Embodiment of this invention.

  Hereinafter, preferred embodiments of the present invention will be described.

<Organic photoelectric conversion element>
One embodiment of the present invention relates to an organic photoelectric conversion element including a conjugated polymer compound having a partial structure represented by the following general formula 1 in a photoelectric conversion layer. That is, the organic photoelectric conversion element according to this embodiment includes a first electrode, a second electrode, and an n-type organic semiconductor and a p-type organic semiconductor that exist between the first electrode and the second electrode. The p-type organic semiconductor contains a conjugated polymer compound having a partial structure represented by the following general formula 1.

According to another embodiment of the present invention, a conjugated polymer compound having a partial structure represented by the following general formula 1 is provided. In addition, although the conjugated polymer compound of the present invention includes one or more partial structures represented by the general formula 1, when there are two or more partial structures, X ¹ and X ² in each partial structure. , D ¹ , D ² , p, and q may be the same as or different from each other.

The conjugated polymer compound according to the present invention has a structure in which donor units (D ¹ , D ² ) are bonded via a unit having a thienothiophene diylidene structure having high mobility and small steric hindrance. It is characterized by. By having such a structure, the conjugated polymer compound can achieve both high mobility and an appropriate energy level, and an organic photoelectric conversion element using the conjugated polymer compound can exhibit sufficient photoelectric conversion efficiency. Here, the mechanism by which the conjugated polymer compound and the organic photoelectric conversion element of the present invention have the above-mentioned effects is not clear, but is presumed as follows. However, the present invention is not limited to the following estimation.

  A polymer having a diketopyrrolopyrrole structure as described in Patent Document 2 has insufficient mobility and could not achieve high photoelectric conversion efficiency. The present inventors examined this reason, and the alkyl group bonded to the nitrogen atom in the diketopyrrolopyrrole structure becomes a steric hindrance and the polymer main chain is twisted, so that the crystallinity is lowered and the mobility is lowered. It is estimated that.

  On the other hand, Shiyan Chen et al. , Chem. Lett. In 2011, 40, p998, a vapor deposition type low molecular material having a thienothiophenedione structure is proposed as an n-type organic thin film transistor material, and it is disclosed that the material has good mobility.

Based on the above estimation, the present inventors combined a unit having a thienothiophene diylidene structure having high mobility and small steric hindrance with a donor unit (D ¹ , D ² ) to provide a conjugated polymer. By constituting the compound, the crystallinity of the conjugated polymer compound can be improved, thereby improving the mobility of the conjugated polymer compound as a p-type organic semiconductor, and as a result, having high photoelectric conversion efficiency. It is estimated that an organic photoelectric conversion element, and thus an organic thin film solar cell can be obtained.

  Further, although details are unknown, it has been found that a conjugated polymer compound having a thienothiophene diylidene structure has good durability. Therefore, an organic photoelectric conversion element having excellent durability can be obtained by using such a conjugated polymer compound.

In the general formula 1, X ¹ and X ² represent ═O (oxygen atom) or ═CR ¹ R ² . X ¹ and X ² may be the same or different, but are preferably the same in terms of enhancing crystallinity and easily obtaining a material with high mobility.

Among these, X ¹ or X ² is ═O (oxygen atom), that is, the partial structure represented by the following general formula 1 preferably has a thienothiophenedione structure. In such a case, a high Voc is expected.

In the general formula 1, R ¹ and R ² are a hydrogen atom (H), a halogen atom (F, Cl, Br, or I), a substituted or unsubstituted alkyl group having 1 to 24 carbon atoms, a carbon atom A fluorinated alkyl group having 1 to 24 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, a fluorinated cycloalkyl group having 3 to 20 carbon atoms, an alkoxy group having 1 to 24 carbon atoms, and 1 to 24 carbon atoms A fluorinated alkoxy group, an alkylthio group having 1 to 24 carbon atoms, a fluorinated alkylthio group having 1 to 24 carbon atoms, an aryl group having 6 to 30 carbon atoms, a fluorinated aryl group having 6 to 30 carbon atoms, A heteroaryl group having 1 to 20 carbon atoms, a fluorinated heteroaryl group having 1 to 20 carbon atoms, or a cyano group (—CN) is represented. R ¹ and R ² may be the same or different, but are preferably the same in terms of enhancing crystallinity and easily obtaining a material with high mobility.

Among these, R ¹ and R ² are preferably a hydrogen atom, an alkyl group having 1 to 24 carbon atoms, a fluorinated alkyl group, an alkoxy group, an alkylthio group, or a cyano group in that both solubility and crystallinity are easily achieved. is there.

  There is no restriction | limiting in particular as said halogen atom, Any of a fluorine atom (F), a chlorine atom (Cl), a bromine atom (Br), and an iodine atom (I) may be sufficient. Among these, a fluorine atom (F) or a chlorine atom is preferable and a fluorine atom (F) is preferable from the viewpoint that side reactions hardly occur during polymerization (Br and I may react with tin). More preferred.

  Although there is no restriction | limiting in particular as said C1-C24 alkyl group, For example, a methyl group, an ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert- Butyl group, n-pentyl group, isopentyl, neopentyl, n-hexyl group, cyclohexyl group, n-heptyl group, n-octyl group, 2-ethylhexyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, 2-tetraoctyl group, n-pentadecyl group, n-hexadecyl group, 2-hexyldecyl group, n-heptadecyl group, 1-octylnonyl group, n- Examples include linear or branched alkyl groups such as octadecyl group, n-nonadecyl group, n-icosyl group, and 2-decyltetradecyl group. That. Among these, from the viewpoint of improving solubility, an alkyl group having 6 to 24 carbon atoms is preferable, and an alkyl group having 8 to 16 carbon atoms is more preferable.

The fluorinated alkyl group having 1 to 24 carbon atoms is not particularly limited, and examples thereof include a group in which at least one hydrogen atom contained in the alkyl group exemplified above is substituted with a fluorine atom. Among these, from the viewpoint of achieving a higher V _oc (deep HOMO level), only the carbon atom closest to the bonding site with the ring (thienothiophene ring) (that is, the 1st carbon atom in the alkyl group) is a fluorine atom. A group substituted with is preferable. Specifically, fluoromethyl group, 1-fluoroethyl group, 1-fluoropropyl group, 1-fluorobutyl group, 1-fluorooctyl group, 1-fluorodecyl group, 1-fluorohexadecyl group, 1-fluoro- Monofluoroalkyl groups such as 2-ethylhexyl group and 1-fluoro-2-hexyldecyl group; difluoromethyl group, 1,1-difluoroethyl group, 1,1-difluoropropyl group, 1,1-difluorobutyl group, 1 , 1-difluorooctyl group, 1,1-difluorodecyl group, 1,1-difluorohexadecyl group, 1,1-difluoro-2-ethylhexyl group, 1,1-difluoro-2-hexyldecyl group, etc. Group; a trifluoroalkyl group such as a trifluoromethyl group, and the like. Moreover, it is preferable that it is a C1-C3 fluorinated alkyl group from a viewpoint of maintaining the applicability | paintability of an upper layer. This is because the number of carbon atoms is sufficiently shorter than other soluble groups (substituents for imparting solubility generally use C6 or more) and have little influence on the upper layer coatability. . Among these, a trifluoromethyl group having 1 carbon atom is more preferable.

  Although there is no restriction | limiting in particular as said C3-C20 cycloalkyl group, For example, a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, a norbornyl group, an adamantyl group etc. are mentioned. Among these, a cycloalkyl group having 4 to 8 carbon atoms is preferable from the viewpoint of improving solubility.

The fluorinated cycloalkyl group having 3 to 20 carbon atoms is not particularly limited, and examples thereof include a group in which at least one hydrogen atom contained in the cycloalkyl group exemplified above is substituted with a fluorine atom. . Among these, from the viewpoint of achieving higher V _oc (deep HOMO level), it is preferable that all the hydrogen atoms contained in the cycloalkyl group exemplified above are groups substituted with fluorine atoms. In view of this, the number and position of fluorine atoms are preferably adjusted appropriately. Moreover, it is preferable that it is a C4-C8 fluorinated cycloalkyl group from a viewpoint of improving solubility.

  The alkoxy group having 1 to 24 carbon atoms is not particularly limited, and examples thereof include methoxy group, ethoxy group, isopropoxy group, tert-butoxy group, n-octyloxy group, n-decyloxy group, and n-dodecyl. Examples thereof include an oxy group, an n-hexadecyloxy group, a 2-ethylhexyloxy group, a 2-hexyldecyloxy group, and a 2-decyltetradecyloxy group. Among these, from the viewpoint of compatibility between solubility and crystallinity, an alkoxy group having 1 to 16 carbon atoms is preferable, and an alkoxy group having 6 to 12 carbon atoms is more preferable.

  The fluorinated alkoxy group having 1 to 24 carbon atoms (fluorinated alkyloxy group) is not particularly limited, and examples thereof include a group in which an oxygen atom is bonded to the root of the fluorinated alkyl group exemplified above. It is done. Among these, from the viewpoint of achieving a higher Voc (deep HOMO level), it is preferable that all the hydrogen atoms contained in the alkyl chain exemplified above are groups substituted with fluorine atoms. It is also preferable that the number and position are adjusted appropriately from the balance. It is a fluorinated alkoxy group having a fluorinated alkyl chain in which only the vicinity of the carbon atom in the substitution site is a fluorine atom that easily achieves both solubility and a deep HOMO level. Further, from the viewpoint of maintaining the coatability of the upper layer, a group in which an oxygen atom is bonded to the root of a fluorinated alkyl group having 1 to 3 carbon atoms is preferable, and a trivalent having 1 carbon atom is particularly preferable. A fluoromethoxy group;

  The alkylthio group having 1 to 24 carbon atoms is not particularly limited, and examples thereof include a methylthio group, an ethylthio group, a propylthio group, an n-butylthio group, a sec-butylthio group, a tert-butylthio group, and an iso-propylthio group. Examples include n-dodecylthio group. Among these, from the viewpoint of achieving both solubility and crystallinity, an alkylthio group having 1 to 16 carbon atoms is preferable, an alkylthio group having 1 to 12 carbon atoms is more preferable, and an alkylthio group having 6 to 12 carbon atoms is further included. preferable.

  The fluorinated alkylthio group having 1 to 24 carbon atoms is not particularly limited, and examples thereof include a group in which a sulfur atom is bonded to the base of the fluorinated alkyl group exemplified above. Among these, from the viewpoint of achieving a higher Voc (deep HOMO level), it is preferable that all the hydrogen atoms contained in the alkyl chain exemplified above are groups substituted with fluorine atoms. It is also preferable to adjust the number and position to an appropriate number in consideration of the above. Further, from the viewpoint of maintaining the coatability of the upper layer, a group in which a sulfur atom is bonded to the base of a fluorinated alkyl group having 1 to 12 carbon atoms is preferable, and the number of carbon atoms is particularly preferably 1. A trifluoromethylthio group;

  The aryl group having 6 to 30 carbon atoms is not particularly limited, and examples thereof include non-condensed hydrocarbon groups such as a phenyl group, a biphenyl group, and a terphenyl group; a pentarenyl group, an indenyl group, a naphthyl group, an azulenyl group, Heptalenyl group, biphenylenyl group, fluorenyl group, acenaphthylenyl group, preadenyl group, acenaphthenyl group, phenalenyl group, phenanthryl group, anthryl group, fluoranthenyl group, acephenanthrenyl group, aceanthrylenyl group, triphenylenyl group, pyrenyl group , Condensed polycyclic hydrocarbon groups such as a chrycenyl group and a naphthacenyl group.

The fluorinated aryl group having 6 to 30 carbon atoms is not particularly limited, and examples thereof include a group in which at least one hydrogen atom contained in the aryl group exemplified above is substituted with a fluorine atom. Among these, from the viewpoint of achieving higher V _oc (deep HOMO level), it is preferable that all the hydrogen atoms contained in the aryl group exemplified above are groups substituted with fluorine atoms. In view of the above, the number and position of fluorine atoms are preferably adjusted appropriately.

  The heteroaryl group having 1 to 20 carbon atoms is not particularly limited. For example, pyridyl group, pyrimidyl group, pyrazinyl group, triazinyl group, furanyl group, pyrrolyl group, thiophenyl group (thienyl group), quinolyl group, Furyl group, piperidyl group, coumarinyl group, silafluorenyl group, benzofuranyl group, benzimidazolyl group, benzoxazolyl group, benzthiazolyl group, dibenzofuranyl group, benzothiophenyl group, dibenzothiophenyl group, indolyl group, carbazolyl group, pyrazolyl Group, imidazolyl group, oxazolyl group, isoxazolyl group, thiazolyl group, indazolyl group, benzothiazolyl group, pyridazinyl group, cinnolyl group, quinazolyl group, quinoxalyl group, phthalazinyl group, phthalazine dionyl group, phthalamidyl group, Romonyl, naphtholactamyl, quinolonyl, naphthalidinyl, benzimidazolonyl, benzoxazolonyl, benzothiazolonyl, benzothiazothionyl, quinazolonyl, quinoxalonyl, phthalazonyl, dioxopyrimidinyl Group, pyridonyl group, isoquinolonyl group, isoquinolinyl group, isothiazolyl group, benzisoxazolyl group, benzisothiazolyl group, indazironyl group, acridinyl group, acridonyl group, quinazoline dionyl group, quinoxaline dionyl group, benzoxazine dionyl Group, benzoxazinonyl group, naphthalimidyl group, dithienocyclopentadienyl group, dithienosylcyclopentadienyl group, dithienopyrrolyl group, benzodithiophenyl group and the like.

The fluorinated heteroaryl group having 1 to 20 carbon atoms is not particularly limited, and examples thereof include a group in which at least one hydrogen atom contained in the heteroaryl group exemplified above is substituted with a fluorine atom. . Among these, from the viewpoint of achieving higher V _oc (deep HOMO level), it is preferable that all of the hydrogen atoms contained in the heteroaryl group exemplified above are groups substituted with fluorine atoms. In view of this, the number and position of fluorine atoms are preferably adjusted appropriately.

The substituent optionally present in R ¹ and R ² is not particularly limited, and examples thereof include a substituted or unsubstituted alkyl group, cycloalkyl group, alkenyl group, alkynyl group, aryl group, heteroaryl group, acyl Group, alkoxycarbonyl group, amino group, alkoxy group, cycloalkyloxy group, aryloxy group, aryloxycarbonyl group, acyloxy group, acylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, sulfonylamino group, sulfamoyl group, Carbamoyl group, alkylthio group, arylthio group, silyl group, sulfonyl group, sulfinyl group, ureido group, phosphoric acid amide group, halogen atom, hydroxyl group, mercapto group, cyano group, sulfo group, carboxyl group, nitro group, hydroxam It can be exemplified group, sulfino group, hydrazino group, and an imino group. In the above, they are not substituted with the same substituent. That is, a substituted alkyl group is not substituted with an alkyl group.

  In the general formula 1, p represents 1 to 4. p is preferably 1 to 2 from the viewpoint of obtaining a high Voc. Moreover, in the said General formula 1, q represents 1-4. q is preferably 1 to 2 from the viewpoint of obtaining a high Voc. Here, p and q may be the same or different, but are preferably the same in terms of enhancing crystallinity and easily obtaining a material with high mobility.

In the general formula 1, D ¹ and D ² represent a donor unit (group) containing a heteroaromatic ring. (More specifically, it represents a donor heteroaromatic ring group and / or a donor heterofused aromatic ring group). Here, the donor units D ¹ and D ² in the general formula 1 may be the same or different. Further, when a plurality of D ¹ and / or D ² are present in one partial structure (p = 2 to 4 and / or q = 2 to 8), only one of D ¹ and D ² is used alone. Or two or more of them may be used in combination.

  In this specification, the “donor unit” means a partial structure in which the LUMO level or the HOMO level is shallower than a hydrocarbon aromatic ring having the same number of π electrons (benzene, naphthalene, anthracene, etc.) Unit). The “unit group” means a partial structure in which two or more units are connected.

  Examples of the donor unit include a unit containing a 5-membered ring such as a thiophene ring, a furan ring, a pyrrole ring, a cyclopentadiene, and a silacyclopentadiene, and a condensed ring thereof. Specific examples include units containing thiophene, thienothiophene, bithiophene, fluorene, silafluorene, carbazole, dithienocyclopentadiene, dithienosilacyclopentadiene, dithienopyrrole, benzodithiophene, and the like. is not.

Hereinafter, specific preferred examples of donor units D ¹ and D ^2.

  In the donor unit (group) of D1 to D24, each R independently represents a hydrogen atom (H), a substituted or unsubstituted alkyl group having 1 to 24 carbon atoms, or the number of carbon atoms. 1 to 24 fluorinated alkyl groups, cycloalkyl groups having 3 to 24 carbon atoms, fluorinated cycloalkyl groups having 3 to 20 carbon atoms, alkoxy groups having 1 to 24 carbon atoms, 1 to 24 carbon atoms Fluorinated alkoxy group, alkylthio group having 1 to 24 carbon atoms, fluorinated alkylthio group having 1 to 24 carbon atoms, aryl group having 6 to 30 carbon atoms, fluorinated aryl group having 6 to 30 carbon atoms, carbon A heteroaryl group having 1 to 20 atoms or a fluorinated heteroaryl group having 1 to 20 carbon atoms is represented. The preferred form of this group is the same as described in the general formula 1.

Among them, ^{D 1} and / or ^{D 2} are heteroaromatic rings containing a sulfur atom (S) donor unit comprising (sulfur-containing heterocyclic aromatic ring) (D1~D11, D16~D24) is preferably. More preferably, it is a group containing a 5-membered sulfur-containing heteroaromatic ring, that is, a group containing thiophene or a thiophene derivative (D1 to D11, D16 to D23). Shiyan Chen et al. , Chem. Lett. In 2011, 40, p998, a phenyl group was used as an aromatic ring connected to a thienothiophenedione group. However, when a 6-membered ring structure such as a phenyl group is used, twisting occurs due to steric hindrance, and the crystallinity is lowered when a polymer is formed, which may greatly impair mobility. On the other hand, by using D ¹ and / or D ² connected to the thienothiophene diylidene structure as a group derived from a 5-membered sulfur-containing heteroaromatic ring, twisting of the polymer main chain is suppressed and higher movement is achieved. It becomes possible to obtain a material of a degree.

  In order to obtain a polymer having high solubility and high molecular weight, a donor unit represented by D1, D5, D6, D8, or D18 is preferable.

  In general, these conjugated polymer materials have a tendency that as the molecular weight increases, the intergranular grain boundaries decrease and the hole mobility increases (see J. Am. Chem. Soc. 2011, 133, p2605). . On the other hand, the solubility of the conjugated polymer is generally low, and the solubility tends to further decrease as the molecular weight increases. From this point of view, in order to ensure sufficient solubility while improving hole mobility, it is preferable to increase the molecular weight using a monomer having high solubility. In order to make such a highly soluble monomer, it is effective to introduce a side chain having a branched chain, and further, a structure that branches from the conjugate plane of the main chain is preferable. It is a unit represented by D8 and D18.

  As long as the conjugated polymer compound of this embodiment has at least one partial structure represented by the above general formula 1, (1) a copolymer consisting of only the partial structure represented by the above general formula 1, Alternatively, (2) a copolymer including the partial structure represented by the general formula 1 and one or more other partial structures may be used.

  The partial structure of the general formula 1 has a structure in which a thienothiophene diylidene structure having an acceptor property is sandwiched between units that can function as a donor (donor unit). The partial structure functions as an acceptor. By combining with a unit (acceptor unit), the adjustment of the HOMO level and the absorption wavelength is improved, and higher photoelectric conversion efficiency can be obtained. For this reason, the conjugated polymer compound according to this embodiment may be a conjugated polymer compound having only the partial structure appearing in the general formula 1 as a repeating unit. It is preferable to further have an acceptor unit (second acceptor unit).

  In this specification, the “acceptor unit” generally means a portion having a LUMO level or a HOMO level deeper than a hydrocarbon aromatic ring having the same number of π electrons (benzene, naphthalene, anthracene, etc.). Structure (unit).

  Preferably, the conjugated polymer compound of this embodiment is a copolymer having a structure in which a donor unit (group) and an acceptor unit (group) are alternately arranged (hereinafter also referred to as “D-A polymer”). ). By using a D-A polymer, the absorption region can be expanded to a long wavelength region. Therefore, such a conjugated polymer compound can absorb light in a long wavelength region (for example, 700 to 1000 nm) in addition to the absorption region (for example, 400 to 700 nm) of a conventional p-type organic semiconductor. Become. As a result, it is possible to absorb a broad spectrum as a photoelectric conversion element and obtain a higher short-circuit current density.

That is, preferably, the conjugated polymer compound of this embodiment has a partial structure represented by the following general formula 2. When the structure represented by the general formula 1 is a polymer linked by a structure represented by -A- or -D ³ -A-, sunlight can be absorbed to a long wavelength. The conjugated polymer compound of the present embodiment includes one or more partial structures represented by the general formula 2. When there are two or more partial structures, X ¹ and X in each partial structure are present. ² , A, D ¹ , D ² , D ³ , p, q, r and s may be the same as or different from each other.

In the general formula 2, X ¹ and X ² represent ═O (oxygen atom) or ═CR ¹ R ² . The preferred forms of X ¹ and X ² are the same as described in the general formula 1.

In the general formula 1, R ¹ and R ² are a hydrogen atom (H), a halogen atom (F, Cl, Br, or I), a substituted or unsubstituted alkyl group having 1 to 24 carbon atoms, a carbon atom A fluorinated alkyl group having 1 to 24 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, a fluorinated cycloalkyl group having 3 to 20 carbon atoms, an alkoxy group having 1 to 24 carbon atoms, and 1 to 24 carbon atoms A fluorinated alkoxy group, an alkylthio group having 1 to 24 carbon atoms, a fluorinated alkylthio group having 1 to 24 carbon atoms, an aryl group having 6 to 30 carbon atoms, a fluorinated aryl group having 6 to 30 carbon atoms, A heteroaryl group having 1 to 20 carbon atoms, a fluorinated heteroaryl group having 1 to 20 carbon atoms, or a cyano group is represented. The preferred form of R ¹ and R ² is the same as described in the general formula 1.

  In the general formula 2, p and r each independently represent an integer of 1 to 4. p and r are preferably 1 to 2 in order to obtain a higher Voc. p and r may be the same or different.

  In the above general formula 2, q represents an integer of 1 to 4. q is preferably 1 to 2 in order to obtain a higher Voc.

  In the general formula 2, s represents an integer of 0 to 4. In order to obtain a higher Voc, s is preferably 1 to 2.

In the general formula 2, D ¹ , D ² , and D ³ are a donor unit (group) containing a heteroaromatic ring (more specifically, a donor heteroaromatic ring group and / or a donor heterofused aromatic group) Ring group). The donor units D ¹ , D ² , and D ³ in the general formula 2 may be the same or different. In addition, when each D ¹ , D ² , and D ³ is present in plural in one partial structure (p = 2 to 4, or q = 2 to 8, or s = 2 to 4), each D ¹ , D ² and D ³ may be used alone or in combination of two or more. Specific examples of D ¹ , D ² , and D ³ include donor units (D1 to D24) including the heteroaromatic ring exemplified as D ¹ and D ² in the general formula 1. The preferred forms of D ¹ , D ² , and D ³ are the same as the preferred forms of D ¹ and D ² in the general formula 1.

  In General Formula 2, A represents an acceptor unit (group) (more specifically, an acceptor aromatic ring group and / or an acceptor condensed aromatic ring group). In addition, acceptor unit A may be used alone or in combination of two or more. When a plurality of A are present in one partial structure (r = 2 to 4), A may be the same or different.

  Below, the preferable specific example of an acceptor property unit is shown.

  In the acceptor units A-1 to A-49, each R independently represents a hydrogen atom (H), a substituted or unsubstituted alkyl group having 1 to 24 carbon atoms, or 1 carbon atom. -24 fluorinated alkyl groups, cycloalkyl groups having 3 to 24 carbon atoms, fluorinated cycloalkyl groups having 3 to 20 carbon atoms, alkoxy groups having 1 to 24 carbon atoms, and fluorine groups having 1 to 24 carbon atoms. Alkoxy group, alkylthio group having 1 to 24 carbon atoms, fluorinated alkylthio group having 1 to 24 carbon atoms, aryl group having 6 to 30 carbon atoms, fluorinated aryl group having 6 to 30 carbon atoms, carbon atom This represents a heteroaryl group having 1 to 20 carbon atoms or a fluorinated heteroaryl group having 1 to 20 carbon atoms. When a plurality of Rs are contained in the unit, the plurality of Rs may be bonded to each other to form a ring that may have a substituent, or the plurality of Rs may be condensed.

Among these, R is preferably a hydrogen atom, an alkyl group having 1 to 24 carbon atoms, a fluorinated alkyl group, an alkoxy group, or an alkylthio group in that both solubility and crystallinity are easily achieved. Specific groups of R and substituents optionally present in R are the same as those described for R ¹ and R ² in the general formula 1.

  The acceptor unit A included in the conjugated polymer compound of this embodiment may include other partial structures (structures having electron withdrawing properties) in addition to the partial structures exemplified above. However, in order to achieve higher photoelectric conversion efficiency, it is preferable that the proportion of the partial structure is larger in the acceptor unit included in the conjugated polymer compound. Specifically, the number of the partial structures (A-1 to A-49) is preferably 50% or more, and 70% or more with respect to the number of all acceptor units contained in the conjugated polymer compound. Is more preferably 90% or more, particularly preferably 95% or more, and most preferably 100%.

  In a preferred embodiment, the acceptor unit represented by A is a divalent group derived from a heteroaromatic condensed polycycle (heteroaromatic condensed polycycle) in which two or more rings are condensed. For example, the acceptor units of A-1 to A-25, A-32 to A-40, and A-45 to A-49. This is because such a compound is expected to improve the short circuit current by increasing the wavelength of the p-type organic semiconductor material and improve the mobility by improving the π plane area. More preferably, A is a structure represented by the general formula 3A or 3B, that is, A-1 to A-18, A-40.

In the general formula 3A or 3B, Y ¹ and Y ² are —O—, —NR ⁵ —, —S—, —C (R ⁶ ) ═C (R ⁷ ) —, —N═C (R ⁸ ). -, or ^-CR 9 ^{R 10} - represents a. In General Formula 3B, each Y ² may be the same or different, but is preferably the same in terms of enhancing crystallinity and easily obtaining a material with high mobility.

Of these, more preferably, Y ¹ and Y ² are —S—. These compounds are expected to have both a deep HOMO level and a high mobility.

In the above formula, R ^{3 to} R ¹⁰ are each independently a hydrogen atom (H), a halogen atom (F, Cl, Br, or I), a substituted or unsubstituted alkyl group having 1 to 24 carbon atoms. , A fluorinated alkyl group having 1 to 24 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, a fluorinated cycloalkyl group having 3 to 20 carbon atoms, an alkoxy group having 1 to 24 carbon atoms, and the number of carbon atoms 1 to 24 fluorinated alkoxy groups, 1 to 24 carbon alkylthio groups, 1 to 24 carbon fluoride alkylthio groups, 6 to 30 aryl groups, 6 to 30 carbon fluorides An aryl group, a C1-C20 heteroaryl group, or a C1-C20 fluorinated heteroaryl group is represented. In General Formula 3A or General Formula 3B, each R ³ and each R ⁴ may be the same or different, but they are the same in terms of enhancing crystallinity and easily obtaining a material with high mobility. It is preferable. Each R ^{3 in the} general formula 3A or R ⁶ and R ⁷ or R ⁹ and R ¹⁰ in the general formula 3A or 3B may be bonded to each other to form a ring that may have a substituent, or It may be condensed.

R ³ or R ⁴ is preferably a hydrogen atom (H), a halogen atom (F, Cl, Br, or I), 1 carbon atom from the viewpoint of the planarity (improving mobility) of the conjugated polymer main chain. To 24 alkyl groups, fluorinated alkyl groups, alkoxy groups, and alkylthio groups, and more preferably, from the viewpoint of obtaining a deeper HOMO conjugated polymer (improvement of open-circuit voltage), a hydrogen atom (H), a halogen atom (F , Cl, Br, or I).

R ^{5 to} R ¹⁰ are preferably a hydrogen atom (H), a halogen atom (F, Cl, Br, or I), from the viewpoint of the solubility of the conjugated polymer, and are easy to achieve both solubility and crystallinity. , A hydrogen atom, an alkyl group having 1 to 24 carbon atoms, a fluorinated alkyl group, an alkoxy group, and an alkylthio group, and more preferably a hydrogen atom (H) and 1 to 1 carbon atoms from the viewpoint of ease of synthesis. 24 alkyl groups.

Specific groups of ^R 3 ^{to R 10 and,} the optional substituents in R 3 ^{to R 10} are the same as described in ^{R 1} and ^{R 2} in the general formula 1.

  Hereinafter, although the preferable form (Exemplary compounds 1-54) of the conjugated polymer compound of this form is illustrated, this invention is not necessarily limited only to the following forms.

  In addition, the molecular weight of the conjugated polymer compound of this embodiment is not particularly limited, but it preferably has an appropriately large molecular weight in order to give a good morphology to the conjugated polymer compound. On the other hand, if the molecular weight is too high, the solubility may be lowered. From such a viewpoint, the number average molecular weight (Mn) of the conjugated polymer compound is preferably 10,000 to 100,000, more preferably 15,000 to 70,000, and 20,000 to More preferably, it is 50,000. In particular, when a bulk heterojunction photoelectric conversion layer is formed using the conjugated polymer compound of this embodiment as a p-type organic semiconductor, a low-molecular compound (for example, a fullerene derivative) is widely used as an n-type organic semiconductor. However, when the molecular weight of the conjugated polymer compound used as the p-type organic semiconductor is within the above range, a microphase separation structure is formed well, and thus carriers that carry holes and electrons generated at the pn junction interface. There is also an advantage that a path is easily formed. The number average molecular weight in this specification can be measured by gel permeation chromatography (GPC; standard material polystyrene).

  By using the conjugated polymer compound of the present embodiment as a p-type organic semiconductor of the photoelectric conversion layer, it is possible to obtain an element having excellent durability and sufficient photoelectric conversion efficiency. That is, an organic photoelectric conversion element according to one embodiment of the present invention includes a first electrode, a second electrode, an n-type organic semiconductor that exists between the first electrode and the second electrode, and p. The p-type organic semiconductor contains the conjugated polymer compound described above.

  Hereinafter, the present embodiment will be described with reference to the accompanying drawings. However, the technical scope of the present invention should be determined by the description of the scope of claims, and is not limited to the following embodiments. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. In addition, the dimensional ratios in the drawings are exaggerated for convenience of explanation, and may be different from the actual ratios.

  FIG. 1 is a schematic cross-sectional view schematically showing a normal layer type organic photoelectric conversion element according to an embodiment of the present invention. Specifically, the organic photoelectric conversion element 10 of FIG. 1 includes an anode (transparent electrode) 11, a hole transport layer 26, a photoelectric conversion layer 14, an electron transport layer 27, and a cathode (counter electrode) 12 on a substrate 25. Are stacked in this order. The substrate 25 is a member that is arbitrarily provided mainly for facilitating the formation of the anode (transparent electrode) 11 thereon by a coating method.

  When the organic photoelectric conversion element 10 shown in FIG. 1 is operated, light is irradiated from the substrate 25 side. In the present embodiment, the anode (transparent electrode) 11 is made of a transparent electrode material (for example, ITO) so that the irradiated light reaches the photoelectric conversion layer 14. The light irradiated from the substrate 25 side reaches the photoelectric conversion layer 14 through the transparent anode (transparent electrode) 11 and the hole transport layer 26.

  The hole transport layer 26 is made of a material having a high hole mobility, and functions to efficiently transport holes generated at the pn junction interface of the photoelectric conversion layer 14 to the anode (transparent electrode) 11. Is responsible. On the other hand, the electron transport layer 27 is formed of a material having high electron mobility, and has a function of efficiently transporting electrons generated at the pn junction interface of the photoelectric conversion layer 14 to the cathode (counter electrode) 12. Yes.

  FIG. 2 is a schematic cross-sectional view schematically showing a reverse layer type organic photoelectric conversion element according to another embodiment of the present invention. The organic photoelectric conversion element 20 in FIG. 2 has the anode 11 and the cathode 12 disposed at opposite positions as compared with the organic photoelectric conversion element 10 in FIG. 1, and the hole transport layer 26, the electron transport layer 27, and the like. Are different in that they are arranged at the opposite positions. That is, in the reverse layer type organic photoelectric conversion element, the first electrode is the cathode (transparent electrode) 12, the second electrode is the anode (counter electrode) 11, and the second electrode and the photoelectric conversion layer 14 It is characterized in that the hole transport layer 26 is included therebetween. In the organic photoelectric conversion element 20 of FIG. 2, a cathode (transparent electrode) 12, an electron transport layer 27, a photoelectric conversion layer 14, a hole transport layer 26, and an anode (counter electrode) 11 are stacked in this order on a substrate 25. It has the composition which becomes. By having such a configuration, electrons generated at the pn junction interface of the photoelectric conversion layer 14 are transported to the cathode (transparent electrode) 12 through the electron transport layer 27, and holes are transported through the hole transport layer 26. It is transported to the anode (counter electrode) 11.

  FIG. 3 is a schematic cross-sectional view schematically illustrating an organic photoelectric conversion element including a tandem (multi-junction type) photoelectric conversion layer according to another embodiment of the present invention. Compared with the organic photoelectric conversion element 10 in FIG. 1, the organic photoelectric conversion element 30 in FIG. 3 replaces the photoelectric conversion layer 14 with a first photoelectric conversion layer 14 a, a second photoelectric conversion layer 14 b, and these The difference is that a laminate of the charge recombination layer 38 interposed between the two photoelectric conversion layers is disposed. In the tandem organic photoelectric conversion element 30 shown in FIG. 3, photoelectric conversion materials (p-type organic semiconductor and n-type organic semiconductor) having different absorption wavelengths are used for the first photoelectric conversion layer 14a and the second photoelectric conversion layer 14b, respectively. By using this, light in a wider wavelength range can be efficiently converted into electricity.

  Hereinafter, each structure of the organic photoelectric conversion element which concerns on this invention is demonstrated in detail.

[electrode]
The organic photoelectric conversion element of this embodiment essentially includes a first electrode and a second electrode. The first electrode and the second electrode each function as an anode or a cathode. In the present specification, “first” and “second” are terms for distinguishing functions as an anode or a cathode. Therefore, the first electrode may function as an anode and the second electrode may function as a cathode. Conversely, the first electrode may function as a cathode and the second electrode may function as an anode. is there. As described above, the carriers (holes / electrons) generated in the photoelectric conversion layer 14 move between the electrodes, and the holes reach the anode 11 and the electrons reach the cathode 12. 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. Moreover, when taking a tandem structure, a tandem structure can be achieved by using a charge recombination layer (intermediate electrode). Furthermore, from the functional aspect of whether or not the electrode has translucency, the translucent electrode is sometimes referred to as a transparent electrode, and the non-translucent electrode is sometimes referred to as a counter electrode. In the case of a normal layer configuration, the anode is usually a transparent electrode having a light transmitting property, and the cathode is a counter electrode having no light transmitting property.

  The material used for the electrode of this embodiment is not particularly limited as long as it is driven as a photoelectric conversion element, and an electrode material that can be used in this technical field can be appropriately employed. In particular, the anode is preferably composed of a material having a relatively large work function compared to the cathode, and conversely, the cathode is composed of a material having a relatively small work function compared to the anode. preferable.

  The anode 11 in the normal layer type organic photoelectric conversion element 10 shown in FIG. 1 is preferably composed of a transparent electrode material having a relatively large work function and capable of transmitting light of 380 to 800 nm. . On the other hand, the cathode 12 has a relatively small work function (for example, 4 eV or less), and can usually be composed of an electrode material having low translucency.

In such a normal layer type organic photoelectric conversion element 10, examples of electrode materials used for the anode (transparent electrode) include metals such as gold, silver, and platinum; indium tin oxide (ITO), SnO _2. And transparent conductive metal oxides such as ZnO; carbon materials such as metal nanowires and carbon nanotubes. It is also possible to use a conductive polymer as the anode electrode material. Examples of the conductive polymer that can be used for the anode include PEDOT: PSS, polypyrrole, polyaniline, polythiophene, polythienylene vinylene, polyazulene, polyisothianaphthene, polycarbazole, polyacetylene, polyphenylene, polyphenylene vinylene, polyacene, and polyphenyl. Examples include acetylene, polydiacetylene, polynaphthalene, and derivatives thereof. These electrode materials may be used alone or as a mixture of two or more materials. It is also possible to form an electrode by laminating two or more layers made of each material. The thickness of the anode (transparent electrode) is not particularly limited, but is usually 10 nm to 10 μm, preferably 100 nm to 1000 nm.

On the other hand, in the normal layer type organic photoelectric conversion element, as an electrode material used for the cathode (counter electrode), a metal, an alloy, an electron conductive compound, and a mixture thereof can be used. Specifically, 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 ) mixture, indium, Examples include lithium / aluminum mixtures, rare earth metals, gold, silver, platinum and other metals. Of these, a mixture of a first metal having a low work function and a second metal, which is a metal having a larger work function and more stable than the first metal, from the viewpoint of electron extraction performance and durability against oxidation, etc. For example, it is preferable to use a magnesium / silver mixture, a magnesium / aluminum mixture, a magnesium / indium mixture, an aluminum / aluminum oxide (Al ₂ O ₃ ) mixture, a lithium / aluminum mixture, aluminum which is a stable metal, or the like. In addition, it is also preferable to use a metal among these materials, so that light that is incident from the first electrode side and transmitted without being absorbed by the photoelectric conversion layer is reflected by the second electrode and is regenerated for photoelectric conversion. The photoelectric conversion efficiency can be improved. These electrode materials may be used alone or as a mixture of two or more materials. It is also possible to form an electrode by laminating two or more layers made of each material. The thickness of the cathode (counter electrode) is not particularly limited, but is usually 10 nm to 5 μm, preferably 100 to 1000 nm.

  In the reverse layer type organic photoelectric conversion element shown in FIG. 2, the cathode 12 is located on the substrate 25 side on which light is incident, and the anode 11 is located on the opposite side. Therefore, the anode 11 in the reverse layer type shown in FIG. 2 is preferably composed of an electrode material having a relatively large work function and usually low translucency. On the other hand, the cathode 12 has a relatively small work function and is made of a transparent electrode material.

  In the reverse layer type organic photoelectric conversion element, examples of the electrode material used for the cathode (transparent electrode) include metals such as gold, silver, copper, platinum, rhodium, ruthenium, aluminum, magnesium, and indium, metal compounds, And carbon materials such as carbon nanoparticles, carbon nanowires, and carbon nanostructures. Among these, it is preferable to use a transparent conductive metal oxide such as indium tin oxide (ITO). These electrode materials may be used alone or as a mixture of two or more materials. It is also possible to form an electrode by laminating two or more layers made of each material. Among these, it is preferable to use carbon nanowires because a transparent and highly conductive cathode can be formed by a coating method. In addition, when a metal material is used, an auxiliary electrode having a thickness of about 1 to 20 nm is formed on the side facing the anode (counter electrode) using, for example, aluminum, an aluminum alloy, silver, a silver compound, or the like. Then, a cathode (transparent electrode) can be obtained by providing a conductive polymer film exemplified as the anode (transparent electrode) material of the above-mentioned normal layer type organic photoelectric conversion element. The thickness of the cathode (transparent electrode) is not particularly limited, but is usually 10 nm to 10 μm, preferably 100 nm to 1 μm.

  On the other hand, in the reverse layer type organic photoelectric conversion element, the electrode material used for the anode (counter electrode) is preferably an electrode material having a relatively higher work function than the cathode (transparent electrode). For example, the anode (counter electrode) may be formed using a metal material such as silver, nickel, molybdenum, gold, platinum, tungsten, and copper. The thickness of the anode (counter electrode) is not particularly limited, but is usually 10 nm to 5 μm, preferably 100 to 1000 nm.

As described above, in the present invention, the organic photoelectric conversion element having the reverse layer structure of FIG. 2 in which a material that hardly deteriorates due to oxygen, moisture, or the like can be used for both the anode and the cathode is preferable. As described above, in the present invention, the reverse layer type organic photoelectric conversion element of FIG. 2 in which a material that is hardly deteriorated by oxygen, moisture, or the like can be used for both the anode and the cathode is preferable. Thus, by setting it as a reverse layer type organic photoelectric conversion element, degradation of the element resulting from oxidation of a counter electrode can be suppressed significantly, and still higher stability can be provided than a normal layer type element. That is, in the organic photoelectric conversion element of the present invention, the first electrode is a transparent electrode, the second electrode is a counter electrode, and between the photoelectric conversion layer and the second electrode, It is preferable that it is a reverse layer type organic photoelectric conversion element which has a positive hole transport layer. Examples of preferred anode / cathode combinations in the reverse layer configuration include, for example, 1) preferred anode / cathode combinations in the reverse layer configuration: 1) first electrode (cathode) ITO, second electrode (anode) silver 2) 1st electrode (cathode) PEDOT: PSS, 2nd electrode (anode) silver 3) 1st electrode (cathode) ITO, 2nd electrode (anode) copper 4) 1st electrode (cathode) PEDOT: PSS, 2nd Electrode (anode) gold 5) first electrode (cathode) ITO, second electrode (anode) PEDOT: PSS
Etc.

[Photoelectric conversion layer]
The photoelectric conversion layer has a function of converting light energy into electric energy using the photovoltaic effect. The organic photoelectric conversion element of this embodiment is characterized in that the photoelectric conversion layer essentially includes the n-type organic semiconductor and the conjugated polymer compound of the present invention as a p-type organic semiconductor. When light is absorbed by these photoelectric conversion materials, excitons are generated, which are separated into holes and electrons at the pn junction interface.

  The photoelectric conversion layer of this embodiment essentially contains the above-described conjugated polymer compound of the present invention, and may contain other p-type organic semiconductor materials as necessary. An example of another p-type organic semiconductor material is shown below.

  Examples of the condensed polycyclic aromatic low molecular weight compound include anthracene, tetracene, pentacene, hexacene, heptacene, chrysene, picene, fluorene, pyrene, peropyrene, perylene, terylene, quaterylene, coronene, ovalene, thacumanthracene, bisanthene, zeslene. , Heptazethrene, pyranthrene, violanthene, isoviolanthene, cacobiphenyl, anthradithiophene, etc., porphyrin, copper phthalocyanine, tetrathiafulvalene (TTF) -tetracyanoquinodimethane (TCNQ) complex, bisethylenedithiotetrathiafulvalene (BEDTTTTF) -perchloric acid complex, and derivatives and precursors thereof.

  Examples of the derivative having the above condensed polycycle include International Publication No. 03/16599, International Publication No. 03/28125, US Pat. No. 6,690,029, JP-A No. 2004-107216, etc. A pentacene derivative having the substituent described in U.S. Pat. No. 2003/136964, a pentacene precursor; 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 the like.

  As the conjugated polymer, for example, 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, a polythiophene-diketopyrrolopyrrole copolymer described in WO2008 / 000664, and a polythiophene-thiazolothiazole copolymer described in Adv Mater, 2007, p4160. Combined, 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.

  Among these compounds, compounds that have high solubility in organic solvents to the extent that solution processing is possible, can form a crystalline thin film after drying, and can achieve high mobility are preferable. More preferably, it is a compound (a compound capable of forming an appropriate phase separation structure) having appropriate compatibility with the fullerene derivative which is the n-type organic semiconductor material of the present invention.

  In addition, when forming an electron transport layer or a hole blocking layer by a solution process on the bulk heterojunction layer, if it can be further applied on the layer once applied, it can be easily laminated, When a layer is further laminated by a solution process on a layer made of a material that usually has good solubility, there is a problem that the layer cannot be laminated because the underlying layer is dissolved. Therefore, a material that can be insolubilized after application by a solution process is preferable.

  Examples of such materials include materials that can be insolubilized by polymerizing the coating film after coating, such as polythiophene having a polymerizable group described in Technical Digest of the International PVSEC-17, Fukuoka, Japan, 2007, P1225. Or a material in which soluble substituents react and become insoluble (pigmented) by applying energy such as heat, as described in US Patent Application Publication No. 2003/136964, and Japanese Patent Application Laid-Open No. 2008-16834 And so on.

  In addition, as long as the p-type organic semiconductor contained in the photoelectric converting layer of this form contains the above-mentioned conjugated polymer compound, the content of the other p-type organic semiconductor material is not particularly limited. However, in order to achieve higher photoelectric conversion efficiency, with respect to the total amount of the p-type organic semiconductor included in the photoelectric conversion layer (when two or more photoelectric conversion layers are included, the total amount in all layers), The larger the proportion of the conjugated polymer compound described above, the better. Specifically, the ratio of the conjugated polymer compound to the total amount of the p-type organic semiconductor is preferably 50% by mass or more, more preferably 70% by mass or more, and 90% by mass or more. More preferably, it is particularly preferably 95% by mass or more, and most preferably 100% by mass.

  The n-type organic semiconductor used in the photoelectric conversion layer of the present embodiment is not particularly limited as long as it is an organic compound that has an acceptor property (electron-accepting property) with respect to the p-type organic semiconductor, and can be used in this technical field. Materials can be adopted as appropriate. Such a compound may be a compound deeper by 0.2 to 0.5 eV or more than the LUMO level of the p-type organic semiconductor, such as fullerene, carbon nanotube, octaazaporphyrin, and the p-type organic semiconductor. Perfluoro compounds in which hydrogen atoms are substituted with fluorine atoms (for example, perfluoropentacene and perfluorophthalocyanine), naphthalenetetracarboxylic anhydride, naphthalenetetracarboxylic diimide, perylenetetracarboxylic anhydride, perylenetetracarboxylic diimide And the like, and polymer compounds containing an aromatic carboxylic acid anhydride and the imidized product thereof as a skeleton.

  Of these, fullerenes, carbon nanotubes, or derivatives thereof are preferably used from the viewpoint that charge separation can be efficiently performed with a p-type organic semiconductor at high speed (up to 50 fs). More specifically, fullerene C60, fullerene C70, fullerene C76, fullerene C78, fullerene C84, fullerene C240, fullerene C540, mixed fullerene, fullerene nanotube, multi-walled carbon nanotube, single-walled carbon nanotube, carbon nanohorn (conical type), etc. , And some of these are hydrogen atoms, halogen atoms (fluorine atoms, chlorine atoms, bromine atoms, iodine atoms), substituted or unsubstituted alkyl groups, alkenyl groups, alkynyl groups, aryl groups, heteroaryl groups, And a fullerene derivative substituted with a cycloalkyl group, a silyl group, an ether group, a thioether group, an amino group, or the like.

  In particular, [6,6] -phenyl-C61-butyric acid methyl ester (abbreviation PC60BM, PC61BM), [6,6] -phenyl-C61-butyric acid-nbutyl ester (PCBnB), [6,6] -Phenyl-C61-butyric acid-isobutyl ester (PCBiB), [6,6] -Phenyl-C61-butyric acid-n hexyl ester (PCBH), [6,6] -Phenyl-C71-butyric acid methyl Esters (abbreviation PC70BM), Adv. Mater. , Vol. 20 (2008), p2116, aminated fullerene described in JP-A 2006-199674, metallocene fullerene described in JP-A 2008-130889, US Pat. No. 7,329,709 It is preferable to use a fullerene derivative whose solubility is improved by a substituent, such as fullerene having a cyclic ether group described in the specification. In this embodiment, the n-type organic semiconductor may be used alone or in combination of two or more.

  There is no particular limitation on the junction form of the p-type organic semiconductor and the n-type organic semiconductor in the photoelectric conversion layer of this embodiment, and it may be a planar heterojunction or a bulk heterojunction (bulk heterojunction). Good. A planar heterojunction is a junction in which a p-type organic semiconductor layer containing a p-type organic semiconductor and an n-type organic semiconductor layer containing an n-type organic semiconductor are stacked, and the surface where these two layers contact is the pn junction interface. It is a form. On the other hand, a bulk heterojunction is formed by applying a mixture of a p-type organic semiconductor and an n-type organic semiconductor. In this single layer, a domain of the p-type organic semiconductor and a domain of the n-type organic semiconductor are formed. It has a microphase separation structure. Therefore, in a bulk heterojunction, many pn junction interfaces exist throughout the layer as compared to a planar heterojunction. Therefore, most of the excitons generated by light absorption can reach the pn junction interface, and the efficiency leading to charge separation can be increased. For these reasons, the junction between the p-type organic semiconductor and the n-type organic semiconductor in the photoelectric conversion layer of this embodiment is preferably a bulk heterojunction.

  The bulk heterojunction layer is formed of a single layer (i layer) in which a normal p-type organic semiconductor material and an n-type organic semiconductor layer are mixed, and the i layer is made of a p-type organic semiconductor. In some cases, it has a three-layer structure (p-i-n structure) sandwiched between a p layer and an n layer made of an n-type organic semiconductor. Such a pin structure has higher rectification of holes and electrons, reduces loss due to recombination of charge-separated holes and electrons, and can achieve higher photoelectric conversion efficiency. .

  In the present invention, the mixing ratio of the p-type organic semiconductor and the n-type organic semiconductor contained in the photoelectric conversion layer is preferably in the range of 2: 8 to 8: 2, more preferably 3.3: 6.7. It is the range of -5: 5. Moreover, the film thickness of one photoelectric conversion layer is preferably 50 to 400 nm, more preferably 80 to 300 nm, and particularly preferably 100 to 200 nm. In general, from the viewpoint of absorbing more light, it is preferable that the thickness of the photoelectric conversion layer is larger. However, as the film thickness increases, the extraction efficiency of carriers (holes / electrons) decreases, so the photoelectric conversion efficiency decreases. Tend to. However, when a photoelectric conversion layer is formed using the conjugated polymer compound of the present embodiment described above as a p-type organic semiconductor material, a film having a thickness of 100 nm or more is formed as compared with a photoelectric conversion layer using a conventional p-type organic semiconductor material. Even when the thickness is increased, the extraction efficiency of carriers (holes / electrons) is unlikely to decrease, so that high photoelectric conversion efficiency can be maintained. Therefore, in the reverse layer type photoelectric conversion element, sufficient photoelectric conversion efficiency can be achieved even when the film thickness of the photoelectric conversion layer is increased.

(substrate)
The organic photoelectric conversion element of the present invention may include a substrate as necessary. The substrate has a role as a member to be coated with a coating solution when the electrode is formed by a coating method.

  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, polyolefins such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyester resin film such as modified polyester, polyethylene (PE) resin film, polypropylene (PP) resin film, polystyrene resin film, cyclic olefin resin, etc. Resin films, vinyl resin films such as polyvinyl chloride and polyvinylidene chloride, polyether ether ketone (PEEK) resin films, polysulfone (PSF) resin films, polyether sulfone (PES) resin films, polycarbonate (PC) resin films , Polyamide resin film, polyimide resin film, acrylic resin film, triacetyl cellulose (TAC) resin film, and the like. If the resin film transmittance of 80% or more in from zero to eight hundred nanomolar), 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. More preferred are a stretched polyethylene terephthalate film and a biaxially stretched polyethylene naphthalate film.

  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.

  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.

(Hole transport layer)
The organic photoelectric conversion element of this form can contain a positive hole transport layer as needed. The hole transport layer has a function of transporting holes and a property of extremely small ability to transport electrons (for example, 1/10 or less of the mobility of holes). The hole transport layer is provided between the photoelectric conversion layer and the anode and prevents recombination of electrons and holes by blocking the movement of electrons while transporting holes to the anode. Can do.

  There is no restriction | limiting in particular in the hole transport material used for a hole transport layer, The material which can be used in this technical field can be employ | adopted suitably. As an example, for example, PEDOT: PSS such as product name BaytronP manufactured by Clevios, polythienothiophenes described in European Patent No. 1647566, sulfonated polythiophenes described in JP 2010-206146, polyaniline, and the like Examples thereof include cyan compounds described in International Publication No. 2006/019270.

  Also, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives , Stilbene derivatives, silazane derivatives, aniline copolymers, and conductive polymer oligomers, particularly thiophene oligomers, can also be used.

  Besides these, a porphyrin compound, an aromatic tertiary amine compound, a styrylamine compound, and the like can be used, and among these, it is preferable to use an aromatic tertiary amine compound. In some cases, the hole transport layer may be formed using an inorganic compound such as a metal oxide such as molybdenum, vanadium, or tungsten, or a mixture thereof.

  Further, a polymer material in which a structural unit contained in the above compound is introduced into a polymer chain, or a polymer material having the above compound as a polymer main chain can also be used as a hole transport material. JP-A-11-251067, J. Org. Huang et. al. , Applied Physics Letters, 80 (2002), p. A p-type hole transport material as described in 139 can also be used. Furthermore, a hole transport material with high p property doped with impurities can be used. For example, JP-A-4-297076, JP-A-2000-196140, JP-A-2001-102175, J. Pat. Appl. Phys. 95, 5773 (2004), and the like. In addition, these hole transport materials may be used individually by 1 type, and may use 2 or more types together. It is also possible to form a hole transport layer by laminating two or more layers made of each material.

  The thickness of the hole transport layer is not particularly limited, but is usually 1 to 2000 nm. From the viewpoint of further improving the leak prevention effect, the thickness is preferably 5 nm or more. Further, from the viewpoint of maintaining high transmittance and low resistance, the thickness is preferably 1000 nm or less, and more preferably 200 nm or less.

In general, the conductivity of the hole transport layer is preferably as high as possible. However, if the conductivity is too high, the ability to prevent electrons from moving may be reduced, and rectification may be reduced. Therefore, the conductivity of the hole transport layer is preferably 10 ⁻⁵ to 1 S / cm, and more preferably 10 ⁻⁴ to 10 ⁻² S / cm.

(Electron transport layer)
The organic photoelectric conversion element of this form can contain an electron carrying layer as needed. The electron transport layer has a property of transporting electrons and having a remarkably small ability to transport holes. The electron transport layer is provided between the photoelectric conversion layer and the cathode, and prevents the recombination of electrons and holes by blocking the movement of holes while transporting electrons to the cathode. it can.

  There is no restriction | limiting in particular in the electron transport material used for an electron carrying layer, The material which can be used in this technical field can be employ | adopted suitably. For example, octaazaporphyrin, a perfluoro body of a p-type organic semiconductor (perfluoropentacene, perfluorophthalocyanine, etc.) can be used. The electron transport layer having a deep HOMO level is provided with a hole blocking function having a rectifying effect so that holes generated in the photoelectric conversion layer do not flow to the cathode side. Therefore, more preferably, a material deeper than the HOMO level of the n-type organic semiconductor is used as the electron transport material. Examples of such electron transport materials include phenanthrene compounds such as bathocuproine, n-type organic semiconductors such as naphthalenetetracarboxylic anhydride, naphthalenetetracarboxylic acid diimide, perylenetetracarboxylic acid anhydride, perylenetetracarboxylic acid diimide, and oxidation. N-type inorganic oxides such as titanium, zinc oxide, and gallium oxide, and alkali metal compounds such as lithium fluoride, sodium fluoride, and cesium fluoride can be used. Moreover, the layer which consists of a n-type organic semiconductor single-piece | unit used for the photoelectric converting layer can also be used. In addition, these electron transport materials may be used individually by 1 type, and may use 2 or more types together. It is also possible to form an electron transport layer by stacking two or more layers made of each material.

  As described above, in the case of an inverted layer type element that is advantageous from the viewpoint of durability, the photoelectric conversion layer is formed after the electron transport layer is formed on the first electrode. A compound that is insoluble in the coating liquid to be contained is preferred as the electron transport material. From such a viewpoint, the electron transport material is preferably an inorganic substance such as titanium oxide or zinc oxide, or a crosslinkable organic substance such as polyethyleneimine or an aminosilane coupling agent described in International Publication No. 2008-134492. Of these, aminosilane coupling agents (3- (2-aminoethyl) -aminopropyltrimethoxysilane, for example) are preferably used.

  Moreover, as a material insoluble with respect to the solvent used when apply | coating a photoelectric converting layer, (pi) conjugated polymer etc. soluble in alcohol can be mentioned, APPLIED PHYSICS LETTERS 95 (2009), p043301, Adv. . Funct. Mat. 2010, p. 1977, Adv. Mater. , 2011, 23, 3086, J.A. Am. Chem. Soc. , 2011, p. 8416, Advanced Materials, 2011 (Vol 23, no. 40), p4636-4463, and the like, and the following polyfluorenes may be used. These polymers are preferable because they can be formed on a normal layer structure, that is, a photoelectric conversion layer, unlike the silane coupling agent and the like described above. In addition, it can function as an electron transport layer / hole blocking layer not only for metal oxides such as ITO but also for metal electrodes such as gold, silver, copper, etc. A metal can be used for the cathode, which is preferable.

  The thickness of the electron transport layer is not particularly limited, but is usually 1 to 2000 nm. From the viewpoint of further enhancing the leak prevention effect, the thickness is preferably 2 nm or more, and more preferably 5 nm or more. Further, from the viewpoint of maintaining high transmittance and low resistance, the thickness is preferably 100 nm or less, and more preferably 20 nm or less.

(Charge recombination layer; intermediate electrode)
In a tandem (multi-junction type) organic photoelectric conversion element having two or more photoelectric conversion layers as shown in FIG. 3, a charge recombination layer (intermediate electrode) is disposed between the photoelectric conversion layers.

  The material used for the charge recombination layer (intermediate electrode) is not particularly limited as long as it is a material having both conductivity and translucency, and examples thereof include ITO, AZO, FTO, and titanium oxide exemplified above. Transparent metal oxides, metals such as Ag, Al, and Au, carbon materials such as carbon nanoparticles and carbon nanowires, and conductive polymers such as PEDOT: PSS and polyaniline can be used. These materials may be used alone or in combination of two or more. It is also possible to form a charge recombination layer by laminating two or more layers made of each material.

The electric conductivity of the charge recombination layer is preferably high from the viewpoint of obtaining high conversion efficiency. Specifically, it is preferably 5 to 50000 S / cm, more preferably 100 to 10,000 S / cm. preferable. The thickness of the charge recombination layer is not particularly limited, but is preferably 1 to 1000 nm, and preferably 5 to 50 nm. By setting the thickness to 1 nm or more, the film surface can be smoothed. On the other hand, by setting the thickness to 1000 nm or less, it is possible to reduce the decrease in the short-circuit current density J _sc (mA / cm ² ).

(Other layers)
The organic photoelectric conversion device of this embodiment may further include other members (other layers) in addition to the above-described members (each layer) in order to improve photoelectric conversion efficiency and improve the lifetime of the device. . Examples of other members include 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. Further, a layer such as a silane coupling agent may be provided in order to make the metal oxide fine particles unevenly distributed in the upper layer more stable. Further, a metal oxide layer may be laminated adjacent to the photoelectric conversion layer of the present invention.

  Moreover, the organic photoelectric conversion element of this invention may have various optical function layers for the purpose of more efficient light reception of sunlight. Examples of the optical functional layer include a light condensing layer such as an antireflection film and a microlens array, and a light diffusion layer that can scatter light reflected by the cathode and enter the power generation layer again.

  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.

<Method for producing organic photoelectric conversion element>
There is no restriction | limiting in particular in the manufacturing method of the organic photoelectric conversion element of the above-mentioned this form, It can manufacture by referring a conventionally well-known method suitably. Hereinafter, the manufacturing method of the reverse layer type organic photoelectric conversion element as shown in FIG. 2 will be described as an example, and a preferable manufacturing method of the organic photoelectric conversion element of this embodiment will be described. However, each process in the manufacturing method is applied not only to the reverse layer type organic photoelectric conversion element but also to the normal layer type organic photoelectric conversion element as shown in FIG. 1 and the tandem type manufacturing as shown in FIG. Is possible.

  The method for producing an organic photoelectric conversion element of the present embodiment includes a step of forming a cathode, a step of forming a photoelectric conversion layer including a p-type organic semiconductor material and an n-type organic semiconductor material on the cathode, and the photoelectric conversion. Forming an anode on the layer. Hereinafter, each process of the manufacturing method of the organic photoelectric conversion element of this form is demonstrated in detail.

  In the manufacturing method of this embodiment, first, a cathode is formed. The method of forming the cathode is not particularly limited, but is easy to operate and can be produced on a roll-to-roll basis using a device such as a die coater. Preferably, the method is a method of applying and drying. Besides this, a commercially available thin film electrode material may be used as it is.

  After forming the cathode as described above, an electron transport layer may be formed on the cathode as necessary. The means for forming the electron transport layer may be either vapor deposition or solution coating, but is preferably solution coating. In the case of forming an electron transport layer using a solution coating method, a solution obtained by dissolving and dispersing the above-described electron transport material in a suitable solvent is coated on the cathode using a suitable coating method and dried. That's fine.

  The coating methods used for the solution coating method include cast method, spin coating method, blade coating method, wire bar coating method, gravure coating method, spray coating method, dipping (dipping) coating method, bead coating method, air knife coating method. Ordinary methods such as a curtain coating method, an ink jet method, a screen printing method, a relief printing method, an intaglio printing method, an offset printing method, a flexographic printing method, and a Langmuir-Blodgett (LB) method can be used. Among these, it is particularly preferable to use a blade coating method.

  The solid content concentration of the solution used in the coating method may vary depending on the coating method and the film thickness, but is preferably 0.01 to 15% by mass, more preferably 0.05 to 10% by mass. In addition, the temperature of the coating liquid and / or the coating surface during coating is not particularly limited, but is preferably 30 to 120 ° C. from the viewpoint of preventing precipitation and unevenness due to temperature fluctuations during coating and drying. More preferably, it is 50-110 degreeC. Furthermore, there is no restriction | limiting in particular also about the specific form of drying, A conventionally well-known knowledge can be referred suitably. An example of the drying conditions is exemplified by conditions such as a temperature of about 80 to 140 ° C. and about several tens of seconds to several tens of minutes. Examples of the apparatus used for drying include a hot plate, hot air drying, an infrared heater, a microwave, and a vacuum dryer. Of course, other drying apparatuses can be used.

  Subsequently, a photoelectric conversion layer including a p-type organic semiconductor and an n-type organic semiconductor is formed on the cathode or the electron transport layer formed as described above. Here, the manufacturing method of this embodiment essentially includes the above-described conjugated polymer compound of the present invention as a p-type organic semiconductor. A specific method for forming the photoelectric conversion layer is not particularly limited, but preferably, a solution in which a p-type organic semiconductor and an n-type organic semiconductor are dissolved or dispersed in an appropriate solvent, respectively or collectively. Then, it may be applied on the cathode or the electron transport layer by using a suitable application method (the specific form is as described above) and dried. A solution in which a p-type organic semiconductor and an n-type organic semiconductor are collectively dissolved and dispersed in a solvent is applied by a coating method. After that, it is preferable to perform heating in order to cause removal of residual solvent, moisture, gas, and improvement of mobility and absorption absorption by 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 photoelectric conversion layer can have an appropriate phase separation structure. As a result, the mobility of holes and electrons (carriers) in the photoelectric conversion layer is improved, and high efficiency can be obtained. In this way, the p-type organic semiconductor and the n-type organic semiconductor are uniformly mixed, and a bulk heterojunction organic photoelectric conversion element can be obtained.

  On the other hand, in the case of forming a photoelectric conversion layer (for example, a p-i-n structure) composed of a plurality of layers having different mixing ratios of a p-type organic semiconductor and an n-type organic semiconductor, the layer is applied after applying one layer. It can be formed by insolubilizing (pigmenting) and then applying another layer.

  Note that the steps after the step of forming the photoelectric conversion layer are preferably performed in a glove box under a nitrogen atmosphere so as not to be exposed to oxygen or moisture. Thus, by performing in a nitrogen atmosphere, it is possible to prevent the p-type organic semiconductor from being deteriorated by oxygen or moisture in the air, and to increase the durability of the element. Specifically, the concentration of oxygen and moisture in the glove box is preferably 1000 ppm or less, and more preferably 100 ppm or less. Most preferably, it is 10 ppm or less.

  Next, an anode is formed on the photoelectric conversion layer formed above. The means for forming the anode is not particularly limited and may be either a vapor deposition method or a solution coating method, but a vapor deposition method (for example, a vacuum vapor deposition method) is preferably used.

  In addition, when providing a positive hole transport layer between a photoelectric converting layer and an anode, a positive hole transport layer is formed using a vapor deposition method or a solution coating method, Preferably a solution coating method. In addition, it is preferable to perform the process of forming the said positive hole transport layer within the glove box of nitrogen atmosphere similarly to the process of forming the said photoelectric converting layer. Thus, by performing in a nitrogen atmosphere, deterioration of the photoelectric conversion layer due to oxygen or moisture in the air can be prevented, and the durability of the element can be improved. Moreover, the conjugated polymer compound according to the present invention has high solvent affinity. Therefore, when forming the hole transport layer using the solution coating method, it is possible to effectively prevent the coating solution containing the hole transport material from being repelled on the surface of the photoelectric conversion layer. The film property can be improved.

  Furthermore, when layers other than the various layers described above are included, a step for forming these layers can be appropriately added by using a solution coating method, a vapor deposition method, or the like.

  The electrodes (cathode / anode), photoelectric conversion layer, hole transport layer, electron transport layer, and the like can be patterned as necessary. The patterning method is not particularly limited, and a known method can be appropriately applied. For example, when patterning soluble materials used in bulk heterojunction type photoelectric conversion layers, hole transport layers, electron transport layers, etc., even if only unnecessary portions are wiped off after the entire surface of die coating, dip coating, etc. Alternatively, direct patterning may be performed at the time of application using a method such as an inkjet method or screen printing. On the other hand, in the case of an insoluble material used for an electrode or the like, mask deposition can be performed at the time of deposition by vacuum deposition, or patterning can be performed by a known method such as etching or lift-off. Alternatively, the pattern may be formed by transferring a pattern formed on another substrate.

  Moreover, the organic photoelectric conversion element of this embodiment can be sealed as necessary in order to prevent deterioration due to oxygen, moisture, and the like in the environment. There is no restriction | limiting in particular in the sealing method, It can carry out by the well-known method used with an organic photoelectric conversion element, an organic electroluminescent element, etc. For example, (1) a method of sealing by bonding a cap made of aluminum or glass with an adhesive; (2) a plastic film on which a gas barrier layer such as aluminum, silicon oxide, or aluminum oxide is formed, and organic photoelectric conversion (3) A method of spin-coating an organic polymer material (polyvinyl alcohol, etc.) having a high gas barrier property; (4) An inorganic thin film (silicon oxide, aluminum oxide, etc.) having a high gas barrier property Alternatively, a method of depositing an organic film (parylene or the like) under vacuum; and (5) a method of laminating these in a composite manner may be mentioned.

<Uses of organic photoelectric conversion elements>
According to the other form of this invention, the solar cell which has the above-mentioned organic photoelectric conversion element is provided. Since the organic photoelectric conversion element of this embodiment has excellent durability and can achieve sufficient photoelectric conversion efficiency, it can be suitably used for a solar cell using this as a power generation element.

  Moreover, according to the further another form of this invention, the optical sensor array by which the organic photoelectric conversion element mentioned above is arranged in the array form is provided. That is, the organic photoelectric conversion element of this embodiment can also be used as an optical sensor array that converts an image projected on the optical sensor array into an electrical signal using the photoelectric conversion function.

  The effect of this invention is demonstrated using a following example and a comparative example. However, the technical scope of the present invention is not limited only to the following examples.

<Synthesis of conjugated polymer compound>
[Synthesis of Exemplified Compound 11]

  Chemische Berichte; vol. 125 (1992); p. With reference to 1235, compound 11-1 was synthesized. Macromolecules, 2010, vol. 43, p. 9779 and Journal of Polymer Science, Part A, 2010, vol. 48, p. With reference to 1714, compound 11-2 was synthesized.

  Compound 11-1 3.28 g (10 mmol), Compound 11-2 7.9 g (22 mmol), and tetrakistriphenylphosphine palladium 1.16 g (1 mmol) were dissolved in 200 ml of dehydrated toluene and reacted at 110 ° C. for 8 hours. It was. After completion of the reaction, the residue was purified by silica gel column chromatography (heptane: toluene = 10: 0 to 8: 2 (volume ratio)) to obtain 5.0 g (9.0 mmol) of compound 11-3 (yield 90%). .

  Subsequently, 558 mg (1.0 mmol) of Compound 11-3 and 390 mg (2.2 mmol) of N bromosuccinimide (NBS) were added to a mixed solvent of 30 ml of methylene chloride and 30 ml of acetic acid, and stirred at room temperature for a whole day and night. After completion of the reaction, brine was added and washed, the organic phase was extracted and dried over magnesium sulfate, and the solvent was distilled off. Subsequently, it was purified by silica gel column chromatography (heptane: toluene = 10: 0 to 8: 2 (volume ratio)) to obtain 667 mg (0.93 mmol) of Compound 11-4 (yield 93%).

  Subsequently, 180 mg (0.25 mmol) of the above compound 11-4 and 2,6-bis (trimethyltin) -4,8-di (2-ethylhexyloxy) cibenzo [1,2-b: 4,5-b ′ 193 mg of dithiophene (synthesized with reference to Journal of the American Chemical Society, 2009, vol. 131, p. 7792, 0.25 mmol) was dissolved in 20 ml of anhydrous toluene. After purging this solution with argon, 6.3 mg (0.007 mmol) of tris (dibenzylideneacetone) dipalladium (0) and 16.7 mg (0.055 mmol) of tris (o-tolyl) phosphine were added. It was. This solution was purged with argon for an additional 15 minutes. Thereafter, the solution was heated to 110 to 120 ° C. and reacted for 72 hours. Furthermore, in order to perform an end cap, 2-tributyltin thiophene (11 mg, 0.03 mmol) was added, and it recirculate | refluxed for 10 hours. Further 2-bromothiophene (10 mg, 0.06 mmol) was added and refluxed for 10 hours. After completion of the reaction, reprecipitation in methanol (500 ml), the polymer product collected by filtration was purified by Soxhlet extraction, and 110 mg of pure polymer (Mn = 15,000) (Exemplary Compound 11) was obtained by reprecipitation in methanol. )

  [Synthesis of Exemplified Compound 19]

  Organic Letters, 2010, p. Compound 19-1 was synthesized with reference to 5478. In addition, Compound 19-2 was synthesized with reference to International Publication No. 2011/131280.

  3.19 g (10 mmol) of Compound 19-1, 7.9 g (22 mmol) of Compound 19-2, and 1.16 g (1 mmol) of tetrakistriphenylphosphine palladium were dissolved in 200 ml of dehydrated toluene and reacted at 110 ° C. for 8 hours. It was. After completion of the reaction, the residue was purified by silica gel column chromatography (heptane: toluene = 10: 0 to 8: 2 (volume ratio)) to obtain 3.8 g (6.8 mmol) of compound 19-3 (yield 68%). .

  Compound 19-3 556 mg (1.0 mmol) was dissolved in 20 ml of dehydrated tetrahydrofuran (THF) under nitrogen, and 1.4 ml (2.2 mmol) of 1.6 M n-butyllithium hexane solution was added dropwise at −78 ° C. 30 After stirring for 30 minutes, 3.0 ml (3.0 mmol) of a 1.0 M trimethyltin chloride 1.0 M hexane solution was added, followed by further stirring for 30 minutes, and then the temperature was raised to room temperature and stirring was performed overnight. After completion of the reaction, ethyl acetate and water were added and washed, and the organic phase was extracted, then magnesium sulfate was added and dried, and the solvent was distilled off. This crude product is subjected to column chromatography on silica gel previously treated with triethylamine (heptane: ethyl acetate = 10: 0 to 9: 1 (volume ratio)), whereby 700 mg (0. 8 mmol) (yield 80%).

  Subsequently, 100 mg of a pure polymer (Mn = 29, 82 mg (0.25 mmol)) and Compound 19-4 (220 mg, 0.25 mmol) were used in the same manner as in the synthesis of Exemplified Compound 11 except that the compound 11-4 (220 mg, 0.25 mmol) was used. 000) (Exemplary Compound 19).

  [Synthesis of Exemplary Compound 21]

  In the synthesis of Exemplified Compound 11, 180 mg of pure polymer (Mn = 25,000) was similarly used except that Compound 21-1 256 mg (0.25 mmol) was used instead of Compound 11-5 (Exemplary Compound 21) Got.

  [Synthesis of Exemplified Compound 25]

  Compound 11-3 1.12 g (2.0 mmol) was dissolved in 50 ml of dehydrated tetrahydrofuran (THF) under nitrogen, and 2.8 ml (4.4 mmol) of 1.6M n-butyllithium hexane solution was added dropwise at −78 ° C. After stirring for 30 minutes, 6.0 ml (6.0 mmol) of 1.0 M trimethyltin chloride 1.0 M hexane solution was added, and the mixture was further stirred for 30 minutes, and then the temperature was raised to room temperature and stirring was performed overnight. After completion of the reaction, ethyl acetate and water were added and washed, and the organic phase was extracted, then magnesium sulfate was added and dried, and the solvent was distilled off. This crude product is subjected to column chromatography on silica gel previously treated with triethylamine (heptane: ethyl acetate = 10: 0 to 9: 1 (volume ratio)), whereby 1.77 g of compound 25-1 ( 2.0 mmol) obtained (quantitative).

  Subsequently, Exemplified Compound 11 was used except that 221 mg (0.25 mmol) of Compound 25-1 and 147 mg of Compound 25-2 (Synthetic with reference to Journal of the American Chemical Society, 2011, p4625, 0.25 mmol) were used. In the same manner as in the synthesis, 200 mg of a pure polymer (Mn = 31,000) (Exemplary Compound 25) was obtained.

  [Synthesis of Exemplified Compound 26]

  Compound 26-2 was synthesized in the same manner as in compound 25-1, except that compound 19-2 was used instead of compound 11-2.

  Next, Synthesis of Exemplified Compound 11 except that 221 mg (0.25 mmol) of Compound 26-2 and 180 mg of Compound 26-3 (Synthesis with reference to Journal of Materials Chemistry, 2011, p 3226, 0.25 mmol) were used. In the same manner, 220 mg of a pure polymer (Mn = 48,000) (Exemplary Compound 26) was obtained.

  [Synthesis of Exemplary Compound 30]

  221 mg (0.25 mmol) of the compound 26-2 and 310 mg of the compound 30-1 (synthesized with reference to J. Am. Chem. Soc., 2012, 134 (7), pp 3498, 0.25 mmol) were used. Except for the above, 220 mg of a pure polymer (Mn = 40,000) (Exemplary Compound 30) was obtained in the same manner as in the synthesis of Exemplified Compound 11.

  [Synthesis of Exemplary Compound 36]

  Compound 36-1 1.23 g (synthesized with reference to Tetrahedron Letters, 1991, p4367, 2 mmol) was dissolved in 25 ml of methylene chloride and 25 ml of acetic acid, and 1.0 g (6.3 mmol) of bromine was added and reacted at room temperature for 96 h. Went. After completion of the reaction, the extract was washed with brine, extracted with methylene chloride, dried over magnesium sulfate, evaporated to remove the solvent, and purified by silica gel column chromatography to obtain 540 mg of Compound 36-2 (yield 35%). .

  In the synthesis of Exemplified Compound 21, 160 mg of a pure polymer (Mn = 20,000) (Exemplary Compound 36) was similarly obtained except that 193 mg (0.25 mmol) of Compound 36-1 was used instead of Compound 11-4. Obtained.

<Preparation of reverse layer type organic photoelectric conversion element>
With reference to the description of International Publication No. 2008-134492 Panfoot, a reverse layer type organic photoelectric conversion device was produced as follows.

[Comparative Example 1]
An indium tin oxide (ITO) transparent conductive film 150 nm deposited (sheet resistance 12 Ω / square cm ² ) as a first electrode (cathode) on a PET substrate using a normal photolithography technique and wet etching. The first electrode was formed by patterning to a width of 10 mm. The patterned first electrode was cleaned 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. After this, the substrate was brought into the glove box and operated under a nitrogen atmosphere.

  On this first electrode, a 0.05 mass% methoxyethanol solution of 3- (2-aminoethyl) -aminopropyltrimethoxysilane manufactured by Aldrich was used with a blade coater so that the dry film thickness was about 5 nm. And dried. Thereafter, a heat treatment was performed at 120 ° C. for 1 minute on a hot plate to form an electron transport layer.

  Next, 0.8% by mass of Comparative Compound 1 (Patent Document 2: synthesized based on International Publication No. 2011-119446), which is a p-type organic semiconductor material, is added to o-dichlorobenzene by an n-type organic semiconductor material. A solution in which a certain PC60BM (nanom spectra E100H made by Frontier Carbon) was mixed at 1.6% by mass was prepared (p-type organic semiconductor material: n-type organic semiconductor material = 33: 67 (mass ratio)), and heated to 110 ° C. After being dissolved by stirring all day and night while heating, it was applied using a blade coater that kept the substrate temperature at 80 ° C. so that the dry film thickness was about 200 nm, and dried at 80 ° C. for 2 minutes as it was. Was formed.

After the drying of the photoelectric conversion layer, as a hole transport layer, PEDOT-PSS (CLEVIOS (registered trademark) PVP AI 4083, manufactured by Helios Co., Ltd., conductivity: 1 × 10 ⁻³ ) composed of a conductive polymer and a polyanion. (S / cm) was diluted with an equal amount of isopropanol, and applied and dried using a blade coater so that the dry film thickness was about 30 nm. Then, it heat-processed for 20 second with 90 degreeC warm air, and formed the positive hole transport layer (organic material layer) which consists of organic substance. The temperature and humidity of the atmosphere at the time of application were 23 ° C. and 65%.

Next, the element was set so that the shadow mask with a width of 10 mm was orthogonal to the transparent electrode, the inside of the vacuum deposition apparatus was depressurized to 1 × 10 ⁻³ Pa or less, and then Ag metal was deposited at a deposition rate of 0.5 nm / second. A second electrode (anode) was formed by laminating 200 nm.

The obtained laminate was transferred to a nitrogen chamber and sandwiched between UBF-9L (water vapor transmission rate 5.0 × 10 ⁻⁴ g / m ² / d) manufactured by Sumitomo 3M, and UV curing as an adhesive. After sealing using resin (manufactured by Nagase ChemteX Corp., UV RESIN XNR5570-B1), it was taken out into the atmosphere, and an organic photoelectric conversion element 1 having a light receiving portion of about 10 × 10 mm size was obtained.

[Examples 1 to 6]
In the formation of the photoelectric conversion layer, a reverse layer type organic photoelectric conversion element was produced in the same manner as in Comparative Example 1 except that each of the compounds shown in Table 1 below was used as the p-type organic semiconductor. .

<Preparation of normal layer type organic photoelectric conversion element>
[Synthesis of Compound P (Electron Transport Material)]
Compound P was synthesized by the following reaction.

  Adv. Mater. Poly (9,9-bis (6-bromohexyl) -4,7-fluorene) was synthesized with reference to 2007, 19, 2010. The weight average molecular weight of this compound was 4400. 1.0 g of this compound and 9.0 g of 3,3′-iminobis (N, N-dimethylpropylamine) (manufactured by Aldrich) were dissolved in a mixed solvent of 100 ml of tetrahydrofuran and 100 ml of N, N-dimethylformamide, and room temperature ( The reaction was carried out at 48 ° C. for 48 hours. After completion of the reaction, the solvent was distilled off under reduced pressure, and reprecipitation was further performed in water to obtain 1.3 g of Compound P (yield 90%). About the obtained compound, the structure was specified by H-NMR. The results are shown below. 7.6-8.0 ppm (br), 2.88 ppm (br), 2.18 ppm (m), 2.08 ppm (s), 1.50 ppm (m), 1.05 ppm (br).

[Example 7]
An indium tin oxide (ITO) transparent conductive film deposited with a thickness of 150 nm (sheet resistance 12 Ω / square) as a first electrode (anode) on a PET substrate is 10 mm wide using a normal photolithography technique and wet etching. To form a first electrode. The patterned first electrode was cleaned 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. Next, PEDOT-PSS (CLEVIOS (registered trademark) PVP AI 4083, manufactured by Helios Co., Ltd., conductivity: 1 × 10 ⁻³ S / cm) made of a conductive polymer and a polyanion is used as a hole transport layer. An isopropanol solution containing 0% by mass was prepared, and the substrate was applied and dried using a blade coater whose temperature was adjusted to 65 ° C. so that the dry film thickness was about 30 nm. Then, it heat-processed with the warm air of 120 degreeC for 20 second, and formed the positive hole transport layer on said 1st electrode. After this, the substrate was brought into the glove box and operated under a nitrogen atmosphere.

  First, the substrate was heat-treated at 120 ° C. for 3 minutes in a nitrogen atmosphere.

  Subsequently, the organic compound which mixed 0.8 mass% of said exemplary compound 37 as a p-type organic-semiconductor material, and 1.6 mass% of PC60BM (nanospectra E100H made from a frontier carbon) which is an n-type organic-semiconductor material in o-dichlorobenzene. A photoelectric conversion material composition solution was prepared (p-type organic semiconductor material: n-type organic semiconductor material = 33: 67 (mass ratio)), and completely dissolved by stirring (60 minutes) while heating to 100 ° C. on a hot plate. After that, the substrate was applied using a blade coater adjusted to 40 ° C. so that the dry film thickness was about 170 nm, and dried at 120 ° C. for 2 minutes, and the photoelectric conversion layer was placed on the hole transport layer. A film was formed.

  Subsequently, the compound P was dissolved in a mixed solvent of 1-butanol: hexafluoroisopropanol = 1: 1 so as to be 0.02% by mass, respectively, to prepare a solution. This solution was applied and dried using a blade coater whose temperature was adjusted to 65 ° C. so that the dry film thickness was about 5 nm. Thereafter, heat treatment was performed for 2 minutes with warm air at 100 ° C. to form an electron transport layer on the photoelectric conversion layer.

Next, the substrate on which the electron transport layer was formed was placed in a vacuum deposition apparatus. Then, the element was set so that the shadow mask with a width of 10 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 silver was deposited at a deposition rate of 2 nm / second, and 100 nm was deposited. Then, a second electrode (cathode) was formed on the electron transport layer.

The obtained organic photoelectric conversion element was moved to a nitrogen chamber, and sandwiched between ^two 3M Ultra Barrier Solar Film UBL-9L (water vapor transmission rate <5 × 10 ⁻⁴ g / m ² / d) and adhered. After sealing using a UV curable resin (manufactured by Nagase ChemteX Corporation, UV RESIN XNR5570-B1) as an agent, the organic photoelectric conversion element 9 having a light receiving portion of about 10 × 10 mm size is taken out under the atmosphere. Produced.

<Evaluation of organic photoelectric conversion element>
<Measurement of hole mobility>
Formed from Au having a thickness of 100 nm on an n-type Si wafer having a specific resistance of 0.02 Ω · cm having a silicon oxide film having a thickness of 230 nm formed by thermal oxidation, a shape having W = 1000 μm and L = 10 μm The to-source / drain electrode pattern was formed.

  The substrate having the source / drain electrode pattern was washed with acetone / isopropanol, and then dry-cleaned at 70 ° C. for 10 minutes using a UV ozone cleaner UV-1 manufactured by SAMCO.

  Next, a monomolecular film made of pentafluorobenzenethiol (hereinafter sometimes abbreviated as “PFBT”) on the source / drain electrodes is immersed in a 0.1M ethanol solution of PFBT for 2 minutes, and then washed several times with ethanol. Formed by doing.

  Then, hexamethyldisilazane (HMDS) is spin-coated at 4000 rpm for 30 seconds on the above substrate, dried at 90 ° C. for 90 seconds, washed with toluene, and a monomolecular film made of HMDS on the silicon oxide film surface. Formed.

  Next, the comparative compound and the exemplary compound of the present invention (organic semiconductor material) were each dissolved in dichlorobenzene at a concentration of 0.5% by mass, and this solution was added at 1000 rpm on the monomolecular film formed above. Was spin-coated for 30 seconds to form an organic semiconductor layer.

  For each organic semiconductor material, using each organic thin film transistor, using a semiconductor parameter measuring apparatus B1500 manufactured by Agilent Technologies, the drain bias is −80 V, the gate bias is swept from 0 V to −80 V, and the positive characteristics are obtained from the IV characteristics. The hole mobility was calculated, and the average value for the four elements was calculated as the carrier mobility of the organic semiconductor material.

(Evaluation of open circuit voltage, fill factor, and photoelectric conversion efficiency)
The organic photoelectric conversion elements obtained in Examples 1 to 7 and Comparative Example 1 were sealed with an epoxy resin and a glass cap, respectively. A solar simulator (AM1.5G filter) is used to irradiate light with an intensity of 100 mW / cm ² , a mask with an effective area of 1 cm ² is overlaid on the light receiving part, and IV characteristics are evaluated, thereby short-circuit current density J _sc (mA / cm ² ), open circuit voltage V _oc (V), and fill factor FF were measured. From the obtained values of J _sc , V _oc and FF, photoelectric conversion efficiency η [%] was calculated according to the following formula 1. The results are shown in Table 1.

(Durability evaluation)
Each of the organic photoelectric conversion elements obtained in Examples 1 to 7 and Comparative Example 1 was stored in a container maintained at a temperature of 80 ° C. and a humidity of 80%, taken out periodically, and measured for IV characteristics. The conversion efficiency was set to 100, and the time when the initial efficiency was reduced to 80% was evaluated as LT80 [time]. It means that durability is so favorable that the value of LT80 is large. The results are shown in Table 1.

  From the results of Table 1, the example using the conjugated polymer compound of the present invention shows that the mobility of the p-type organic semiconductor layer is better than that of the comparative example, and a high photoelectric conversion efficiency η can be obtained. Indicated. In addition, regarding the durability evaluation (LT80) of the device, the durability of each of the examples was significantly improved as compared with the comparative example.

  Furthermore, it was shown that an organic thin film solar cell with higher durability can be obtained by placing the compound of the present invention in an organic photoelectric conversion element having a reverse layer structure.

10, 20, 30 organic photoelectric conversion element,
11 Anode,
12 cathode,
14 photoelectric conversion layer,
14a 1st photoelectric conversion layer,
14b second photoelectric conversion layer,
25 substrates,
26 hole transport layer,
27 electron transport layer,
38 Charge recombination layer.

Claims (11)

A first electrode;
A second electrode;
A photoelectric conversion layer including an n-type organic semiconductor and a p-type organic semiconductor, which exists between the first electrode and the second electrode;
Have
The p-type organic semiconductor includes an organic photoelectric conversion element including a conjugated polymer compound having a partial structure represented by the following general formula 1;
In the formula, X ¹ and X ² each independently represent ═O or ═CR ¹ R ² ,
R ¹ and R ² each independently represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 24 carbon atoms, a fluorinated alkyl group having 1 to 24 carbon atoms, or 3 carbon atoms. -20 cycloalkyl group, fluorinated cycloalkyl group having 3 to 20 carbon atoms, alkoxy group having 1 to 24 carbon atoms, fluorinated alkoxy group having 1 to 24 carbon atoms, alkylthio having 1 to 24 carbon atoms Group, a fluorinated alkylthio group having 1 to 24 carbon atoms, an aryl group having 6 to 30 carbon atoms, a fluorinated aryl group having 6 to 30 carbon atoms, a heteroaryl group having 1 to 20 carbon atoms, or a carbon atom Represents a fluorinated heteroaryl group of number 1 to 20, or a cyano group,
D ¹ and D ² each independently represent a donor unit containing a heteroaromatic ring,
p represents an integer of 1 to 4,
q represents the integer of 1-4. The organic photoelectric conversion device according to claim 1, wherein X ¹ and X ² are ═O. The organic photoelectric conversion element according to claim 1 or 2, wherein the conjugated polymer compound has a partial structure represented by the following general formula 2.
In the formula, X ¹ and X ² each independently represent ═O or ═CR ¹ R ² ,
R ¹ and R ² each independently represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 24 carbon atoms, a fluorinated alkyl group having 1 to 24 carbon atoms, or 3 carbon atoms. -20 cycloalkyl group, fluorinated cycloalkyl group having 3 to 20 carbon atoms, alkoxy group having 1 to 24 carbon atoms, fluorinated alkoxy group having 1 to 24 carbon atoms, alkylthio having 1 to 24 carbon atoms Group, a fluorinated alkylthio group having 1 to 24 carbon atoms, an aryl group having 6 to 30 carbon atoms, a fluorinated aryl group having 6 to 30 carbon atoms, a heteroaryl group having 1 to 20 carbon atoms, or a carbon atom Represents a fluorinated heteroaryl group of number 1 to 20, or a cyano group,
D ¹ , D ² , and D ³ each independently represent a donor unit containing a heteroaromatic ring;
A represents an acceptor unit,
p and r each independently represents an integer of 1 to 4;
q represents an integer of 1 to 4,
s represents an integer of 0 to 4.   The organic photoelectric conversion device according to claim 3, wherein A is a heteroaromatic condensed polycycle in which two or more rings are condensed. The organic photoelectric conversion device according to claim 3 or 4, wherein A is represented by the following general formula 3A or 3B.
In the formula, Y ¹ and Y ² are each independently —O—, —NR ⁵ —, —S—, —C (R ⁶ ) ═C (R ⁷ ) —, —N═C (R ⁸ ). -, or ^-CR 9 ^{R 10} - represents,
R ^{3 to} R ¹⁰ each independently represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 24 carbon atoms, a fluorinated alkyl group having 1 to 24 carbon atoms, or 3 carbon atoms. -20 cycloalkyl group, fluorinated cycloalkyl group having 3 to 20 carbon atoms, alkoxy group having 1 to 24 carbon atoms, fluorinated alkoxy group having 1 to 24 carbon atoms, alkylthio having 1 to 24 carbon atoms Group, a fluorinated alkylthio group having 1 to 24 carbon atoms, an aryl group having 6 to 30 carbon atoms, a fluorinated aryl group having 6 to 30 carbon atoms, a heteroaryl group having 1 to 20 carbon atoms, or a carbon atom Represents a fluorinated heteroaryl group of 1 to 20, wherein each R ³ or R ⁶ and R ⁷ or R ⁹ and R ¹⁰ are bonded to each other to form an optionally substituted ring. The Well, or, it may be condensed. The organic photoelectric conversion device according to claim 5, wherein Y ¹ and Y ² are —S—;   The organic photoelectric conversion element according to claim 1, wherein the conjugated polymer compound has a number average molecular weight of 10,000 to 100,000. The first electrode is a transparent electrode;
The second electrode is a counter electrode;
The organic photoelectric conversion element according to any one of claims 1 to 7, further comprising a hole transport layer between the photoelectric conversion layer and the second electrode.   The solar cell which has an organic photoelectric conversion element of any one of Claims 1-9. A conjugated polymer compound having a partial structure represented by the following general formula 1.
X ¹ and X ² each independently represent ═O or ═CR ¹ R ² ,
R ¹ and R ² each independently represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 24 carbon atoms, a fluorinated alkyl group having 1 to 24 carbon atoms, or 3 carbon atoms. -20 cycloalkyl group, fluorinated cycloalkyl group having 3 to 20 carbon atoms, alkoxy group having 1 to 24 carbon atoms, fluorinated alkoxy group having 1 to 24 carbon atoms, alkylthio having 1 to 24 carbon atoms Group, a fluorinated alkylthio group having 1 to 24 carbon atoms, an aryl group having 6 to 30 carbon atoms, a fluorinated aryl group having 6 to 30 carbon atoms, a heteroaryl group having 1 to 20 carbon atoms, or a carbon atom Represents a fluorinated heteroaryl group of number 1 to 20, or a cyano group,
D ¹ and D ² each independently represent a donor unit containing a heteroaromatic ring,
p represents each independently an integer of 1 to 4,
q represents the integer of 1-4. A conjugated polymer compound having a partial structure represented by the following general formula 2.
In the formula, X ¹ and X ² each independently represent ═O or ═CR ¹ R ² ,
R ¹ and R ² each independently represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 24 carbon atoms, a fluorinated alkyl group having 1 to 24 carbon atoms, or 3 carbon atoms. -20 cycloalkyl group, fluorinated cycloalkyl group having 3 to 20 carbon atoms, alkoxy group having 1 to 24 carbon atoms, fluorinated alkoxy group having 1 to 24 carbon atoms, alkylthio having 1 to 24 carbon atoms Group, a fluorinated alkylthio group having 1 to 24 carbon atoms, an aryl group having 6 to 30 carbon atoms, a fluorinated aryl group having 6 to 30 carbon atoms, a heteroaryl group having 1 to 20 carbon atoms, or a carbon atom Represents a fluorinated heteroaryl group of number 1 to 20, or a cyano group,
D ¹ , D ² , and D ³ each independently represent a donor unit containing a heteroaromatic ring;
A represents an acceptor unit,
p and r each independently represents an integer of 1 to 4;
q represents an integer of 1 to 4,
s represents an integer of 0 to 4.