JP5258037B2 - Photoelectric conversion element, manufacturing method thereof, and solar cell - Google Patents

Description

  The present invention belongs to a technical field related to a bulk heterojunction type organic thin film, and particularly relates to a photoelectric conversion element that improves photo-electric energy conversion efficiency, a manufacturing method thereof, and a solar cell.

In recent years, as a solar cell using an organic thin film, a bulk-heterojunction solar cell including an active layer in which a donor domain and an acceptor domain are mixed has attracted attention as realizing high power generation efficiency.
The active layer that has absorbed the irradiation light generates excitons inside the donor domain in which electrons and holes are paired and strongly bound to each other. Of the generated excitons, only those that reach the interface between the donor domain and the acceptor domain (hereinafter referred to as domain interface) are involved in power generation by charge separation.

The separated electrons move through the acceptor domain and reach the negative electrode, and the separated holes move through the donor domain and reach the positive electrode, generating a potential difference between the electrodes.
In bulk heterojunction solar cells, the domain interface formed inside the active layer is wide, so that many of the excitons generated reach the domain interface without charge deactivation and charge separation occurs. Efficient power generation is realized.

In order to further improve the power generation efficiency of the bulk heterojunction solar cell, studies have been made to add a dye to the active layer in order to generate many excitons (see, for example, Non-Patent Documents 1 and 2). In addition, studies have been made to optimize the domain sizes of donors and acceptors in order to charge-separate excitons that have been deactivated without reaching the domain interface (see, for example, Non-Patent Document 3).
Sol.Energy Mater.Sol.Cells, 91, 447 (2007) Eur.Phys.J.Appl.Phys., 40,169 (2007) Adv. Funct. Mater., 15, 1193 (2005)

However, attempts to add organic dyes to the active layer have been reported to reduce power generation efficiency, and no expected results have been achieved. The reason for this is not clear, but it is presumed that the conventionally used organic dyes are generally associated with high aggregation properties.
In addition, it is desirable to try to optimize the domain size, but it is desirable that the domain interface expands and the charge separation is promoted when the size is reduced. I can see it.

  The present invention provides a photoelectric conversion element, a manufacturing method thereof, and a solar cell, in which an organic dye is added to an active layer and a structure of a donor domain and an acceptor domain is controlled to improve photo-electric energy conversion efficiency. Make it an issue.

In order to solve the above-described problem, the present invention provides a photoelectric conversion element in which a potential difference is generated between a pair of electrode layers disposed opposite to both sides of an active layer when irradiated with light, and the active layer transmits the irradiated light. absorbed to have the structure of a bulk heterojunction type and the second domain are mixed for receiving the electronic first domain donates electrons excited, organic dye excited by absorbing the irradiation light, and bulk heterojunction characterized in that it is unevenly distributed to the interface between the second domain and the first domain.

  By configuring the invention in this way, the organic dye is thinly and widely distributed at the domain interface. As a result, excitons generated in the first domain reach the domain interface and are separated by charge to participate in power generation. In addition, excitons generated in the organic dye by absorbing the irradiation light are separated into charges on the spot where they are generated, and are involved in power generation with almost no deactivation.

The photoelectric conversion element of the present invention is characterized in that the organic dye contains a functional group that inhibits the overlap of adjacent π-conjugated molecular orbitals.
Furthermore, the organic dye is a complex with an atom capable of taking a non-planar coordination structure.

  By constituting the invention in this way, the organic dye is generally easy to aggregate in the laminating direction of the planar structure as a general property, but aggregation is inhibited by the functional group. As a result, the organic dye is stably fixed on the interface of the domain without self-aggregation.

The photoelectric conversion element of the present invention is characterized in that the absorption peak of the light absorption spectrum of the organic dye is located on the longer wavelength side than the absorption peak of the first domain or the second domain.
The HOMO level of the organic dye is lower than the HOMO level of the donor molecule to function the first domain, and higher than the HOMO level of the acceptor molecule to function the second domain, said organic dye The LUMO level is lower than the LUMO level of the donor molecule and higher than the LUMO level of the acceptor molecule, and the organic dye has a HOMO-LUMO gap smaller than that of the donor molecule. To do.

  By configuring the invention in this way, even an exciton generated at a position distant from the domain interface can efficiently reach the domain interface and excite the organic dye to achieve charge separation. Thereby, most excitons generated in the first domain can contribute to power generation without being deactivated.

Further, the method for producing a photoelectric conversion element of the present invention is a method for producing a photoelectric conversion element in which a potential difference is generated between a pair of electrode layers disposed opposite to both sides of an active layer when irradiated with light, which absorbs the irradiation light. Preparing a solution in which a total of 100 parts by weight of donor molecules that donate excited electrons and acceptor molecules that accept the electrons and 0.1 to 10 parts by weight of an organic dye are dissolved in a solvent, and the electrode layer A step of applying the solution onto a substrate provided with one of the above and volatilizing the solvent; and a bulk heterojunction in which the first domain consisting of the donor molecule and the second domain consisting of the acceptor molecule are phase-separated and mixed Rutotomoni to express structures of the mold, to form the active layer surface to the organic dye is unevenly distributed between the first domains bulk heterojunction with said second domain It includes a step, wherein the organic dye is smaller than that of the HOMO-LUMO gap the donor molecule, HOMO level is lower than the HOMO level of the donor molecule and than the HOMO level of the acceptor molecule High, the LUMO level is lower than the LUMO level of the donor molecule and higher than the LUMO level of the acceptor molecule, is incompatible with the donor molecule and the acceptor molecule, and is more self-aggregated than these It is characterized by smallness.

By configuring the invention in this way, an organic thin film in which donor molecules, acceptor molecules, and organic dyes are mixed can be formed on a substrate by applying the prepared solution by a known means such as a spin cast method. . Further, when the donor molecule is grown as the first domain and the acceptor molecule is grown as the second domain by heat treatment or the like, the organic dye is preferentially deposited on the domain interface.
Further, the organic dye is distributed in the domain interface even if it is an exciton generated at a position distant from the domain interface because the HOMO level and the LUMO level have the above-defined relationship. Can be contributed to power generation by separating the charge.

  According to the present invention, the added organic dye is thinly distributed at the domain interface between the donor and the acceptor, so that the photoelectric conversion element having excellent photo-electrical energy conversion efficiency, its manufacturing method, and solar cell Is provided.

Embodiments of the present invention will be described below with reference to the drawings.
(First embodiment)
As shown in the conceptual diagram of FIG. 1A, the photoelectric conversion element 10 according to the first embodiment includes an active layer 20 and a pair of positive electrode layers 11 (electrode layers) disposed opposite to both ends thereof. It is comprised from the negative electrode layer 12 (electrode layer).
Then, when the irradiation light H is applied from a transparent electrode (positive electrode layer 11 in the figure) of the pair of electrode layers 11 and 12, electrons move from the active layer 20 to the negative electrode layer 12 and from the active layer 20 to the positive electrode. When holes move to the layer 11 (synonymous with electrons moving from the positive electrode layer 11 to the active layer 20), a potential difference is generated between the electrode layers 11 and 12.

  The active layer 20 is an organic thin film having a thickness of 10 nm to 1000 nm, and has a refined first domain 21 (hereinafter also referred to as “donor domain 21”) and second domain 22 (hereinafter referred to as “acceptor domain 22”). The organic dye 23 is unevenly distributed near the interface between both domains.

The donor domain 21 is excited when the irradiation light H is absorbed, and excitons are generated therein. Here, excitation means that the electron in the highest occupied molecular orbital (HOMO) in the molecule transitions to the lowest unoccupied molecular orbital (LUMO) as shown in FIG. Means state.
HOMO (Highest Occupied Molecular Orbital) means a molecular orbital in which unstable electrons are filled last, assuming that electrons are charged sequentially from a stable molecular orbital having a low energy level. On the other hand, LUMO (Lowest Unoccupied Molecular Orbital) means a molecular orbital whose energy level is one higher than that of HOMO, and an orbit in which electrons are not present in a higher energy level orbital.

An exciton refers to a state in which an electron transitioned to LUMO and a hole formed by vacancy of an HOMO electron are bound to each other and paired. The position of the generated excitons can be changed in the donor domain 21 by energy transfer, so that even excitons generated at positions away from the domain interface can reach the domain interface.
When the overlap between the emission spectrum of the donor molecule D forming the donor domain 21 and the absorption spectrum of the organic dye 23 is large, excitons generated in the donor molecule D transfer energy to the organic dye 23, and the domain efficiently. Can reach the interface.

In the exciton, when the absorbed light energy is consumed as fluorescence or heat, the electrons transitioned to LUMO return to HOMO again and are deactivated. In addition, electrons that have transitioned to LUMO are more stable when they enter a lower LUMO than a LUMO with a higher energy level, so if the difference is small, the electrons will pass through the domain interface and transfer charge to a material with a lower LUMO level. Can do.
For this reason, excitons that have been able to reach the domain interface by energy transfer before being deactivated are separated from the paired holes and electrons, and the electrons pass through LUMO in the direction of the negative electrode layer 12. The holes move and move toward the positive electrode layer 11 via the HOMO.

  When the donor domain 21 absorbs the irradiation light H, as shown in FIG. 1B, electrons in the HOMO energy level (HOMO level) are excited to the LUMO energy level (LUMO level). To do. Then, a plurality of excitons are simultaneously generated at an arbitrary position of the donor domain 21 (see (a) and (d) of FIG. 2).

  The donor molecule D constituting the donor domain 21 includes thiophene, phenylene vinylene, fluorene, ruthenium complex, fullerene, coumarin, carbazole, porphyrin, phthalocyanine, spiro, ferrocene, fluorenone, Frugide, imidazole, perylene, phenazine, phenothiazine, polyene, azo, quinone, indigo, diphenylmethane, triphenylmethane, polymethine, acridine, acridinone, carbostyril, coumarin , Diphenylamine, quinacridone, quinophthalone, phenoxazine, phthaloperinone, porphine, chlorophyll, phthalocyanine, crown, squarylium, thiafulvalene, etc. It is below.

The acceptor domain 22 is in contact with the donor domain 21 via a domain interface where the organic dye 23 is distributed, and accepts electrons from the donor domain 21 and the organic dye 23. The function of the acceptor domain 22 is not limited to accepting such electrons. The acceptor domain 22 itself absorbs and excites the irradiation light H to generate holes for the organic dye 23 or electrons for the negative electrode layer 12 (or electron transport). In some cases, it may be provided to layer 40 (FIG. 3).
The acceptor domain 22 preferably has an LUMO energy level (LUMO level) smaller than the LUMO levels of the donor domain 21 and the organic dye 23 and higher than the conduction band level of the negative electrode layer 12.
Specific examples of the acceptor molecule A constituting the acceptor domain 22 include substances such as fullerene, oxadiazole, oxador, perylene, perylene diimide, benzodiimidazole, naphthalene derivatives, and metal complexes.

In the active layer 20, as described above, excitons separate charges at the domain interface, so that the frequency of charge separation increases as the area of the domain interface increases. Then, the holes and electrons after the charge separation are transferred to the positive electrode layer 11 and the negative electrode layer 12 via the donor domain 21 and the acceptor domain 22, respectively. Therefore, each of the domains 21 and 22 needs to be in a two-phase mixed state so as to be in contact with the electrode layer corresponding to the charge transfer destination.
That is, even if the donor domain 21 or the acceptor domain 22 is a closed region and exists inside the active layer 20, the separated electrons and holes cannot reach the corresponding electrode layer, and thus recombine to contribute to power generation. It will not be possible.

The organic dye 23 is preferably uniformly distributed at a domain interface with a thickness of a single molecule to several tens of centimeters, but it is inevitable that there is a missing portion.
The organic dye 23 absorbs irradiated light, and electrons are transferred from HOMO to LUMO to generate excitons.
The absorption spectrum of the organic dye 23 has a good overlap with the emission spectrum of the donor molecule D that forms the domain responsible for light absorption (here, the donor domain 21), and the energy gap Eg2 of HOMO-LUMO is that of the donor domain 21. Those smaller than Eg1 are desirable.

Further, the HOMO and LUMO levels of the organic dye 23 are preferably located between those of the donor domain 21 and the acceptor domain 22, respectively.
Further, the organic dye 23 has a gap between the HOMO levels and a gap between the LUMO levels that are the minimum size required for charge separation with respect to the donor domain 21 and the acceptor domain 22 adjacent to both sides. It is preferred to be selected to take.

As the organic dye 23 (including the case of the donor molecule D), examples of the substance that generates excitons by light irradiation include those having a π-conjugated compound as a main component.
Here, the π-conjugated system refers to a bonded state in which covalent bonds between carbon atoms are alternately single bonds and double bonds. In such a bonded state, π electrons having a molecular orbital plane perpendicular to the straight line connecting the carbon atoms are spread (delocalized) throughout the molecule of the π conjugated compound. It has the property that pi-electrons can move around freely in molecular orbitals.

  The organic dye 23 is preferably incompatible with the donor domain 21 and the acceptor domain 22 and has a smaller self-aggregation property than molecules constituting them. Thereby, the organic pigment | dye 23 can be fixed to the domain interface extensively and stably. Further, as described later, in the process of developing the two-phase separation structure of the donor domain 21 and the acceptor domain 22, the organic dye 23 can be deposited at the domain interface.

However, the above-described π-conjugated compound has a general property that it easily aggregates due to the interaction between molecules caused by the overlap of molecular orbitals of π electrons.
Therefore, the organic dye 23 is preferably one in which aggregation between molecules is inhibited by a bulky substituent and does not strongly self-aggregate. Thereby, the organic pigment | dye 23 can be fixed to the domain interface extensively and stably.
Furthermore, it is preferable that the organic dye 23 exhibits a strong absorption peak similar to the solution state on the long wavelength side than the absorption peak on the longest wavelength side of the donor domain 21 in contact with the domain interface. Thereby, the organic dye 23 can efficiently receive the energy of excitons generated in the donor domain 21.

Such an organic dye 23 is preferably, for example, a molecular structure having a bulky substituent introduced therein, a complex with an atom capable of taking a non-planar coordination structure, or the like. Thereby, the intermolecular distance of the organic dye 23 is separated by several angstroms, and the overlap of the π electron molecular orbitals can be inhibited.
Examples of such a bulky substituent include, but are not limited to, those having a quaternizing element such as a tertiary butyl group, a quaternary ammonium salt, and an alkyl phosphate. The organic dye 23 having such a bulky substituent may be any organic dye having an absorption peak on the longer wavelength side than the absorption peak on the longest wavelength side of the donor, such as an azo dye, a quinone dye, Diaryl and triarylmethane dyes, cyanine dyes, porphyrin dyes, phthalocyanine dyes, naphthalocyanine dyes, indigo dyes, condensed polycyclic dyes, styryl dyes, spiropyran dyes, spirooxazine dyes, squarylium dyes, Examples thereof include, but are not limited to, croconium dyes and pyromethene dyes.

As the complex with it an atom to take a non-planar coordination geometry, azo metal complexes, metal porphyrins, metal Futaroshia two emissions, metal naphthalocyanines phthalocyanines, may be mentioned bipyridine complexes, also central atom Examples thereof include Si and Ge having a coordination number of 6, and examples of the axial ligand include trihexylsilyloxide.
Such a bulky functional group has a function of separating the intermolecular distance by several angstroms, but realizes a condition within 10 angstroms which is an intermolecular distance necessary for charge transfer constituting the photoelectric conversion element of the present invention, This functional group does not hinder the performance as a photoelectric conversion element.

In the positive electrode layer 11 (electrode layer), as shown in FIG. 1B, the energy level of the conduction band of free electrons (hereinafter referred to as the conduction band level) is higher than the HOMO level of the donor domain 21. It is preferable that the gap is small. This facilitates the movement of holes from the donor domain 21 to the positive electrode layer 11.
In the first embodiment, the positive electrode layer 11 is a transparent electrode through which the irradiation light H is transmitted. Specific examples of such a material constituting the transparent electrode include ITO (indium tin oxide), IZO (indium zinc oxide film), TiO ₂ , SnO ₂ , and ZnO.

The negative electrode layer 12 (electrode layer) has a conduction band level higher than the conduction band level of the positive electrode layer 11 described above, and lower than the LUMO level of the acceptor domain 22 in contact with the domain interface. Small is preferable. This facilitates the movement of electrons from the acceptor domain 22 to the negative electrode layer 12.
In the first embodiment, the negative electrode layer 12 is a metallic counter electrode facing the transparent electrode. Specific examples of such a material constituting the counter electrode include Ca, Mg, Al, Ag, and the like.

(Description of operation)
Based on FIG. 2 (see FIG. 1 as appropriate), the operation of the photoelectric conversion element according to the first embodiment will be described. FIG. 2 is an enlarged view of a broken line area portion in the active layer 20 of FIG.
First, when the irradiation light H passes through the transparent electrode (positive electrode layer 11 in FIG. 1) and enters the active layer 20, excitons are generated inside the donor domain 21 ((a) and (d) in FIG. 2). . The generated excitons transfer energy in the donor domain 21 and reach the domain interface.

As described above, the HOMO-LUMO energy gap Eg2 of the organic dye 23 unevenly distributed at the domain interface is smaller than the Eg1 of the donor molecule D, and the emission spectrum of the donor molecule and the absorption spectrum of the organic dye 23 overlap each other. For this reason, excitons generated in the donor domain 21 efficiently transfer energy to the organic dye 23 and immediately charge-separate (FIG. 2B).
Thus, excitons generated in the donor domain 21 are excitons generated in the donor domain 21 at a position away from the domain interface in order to separate charges after energy transfer to the organic dye 23 (see FIG. 2 (d)), leading to charge separation without deactivation (FIG. 2 (e)).
Due to this energy transfer, excitons generated in the organic dye 23 undergo charge separation at the domain interface, and the generated electrons move to the conduction band of the negative electrode layer 12 via the LUMO of the acceptor domain 22, and generated holes. Moves to the conduction band of the positive electrode layer 11 via the HOMO of the donor domain 21 (FIG. 2C).

Although not shown in the drawing, in a portion where the film of the organic dye 23 is thick, excitons generated in the donor domain 21 may move to either one of the interfaces at both ends of the organic dye 23 and then charge separate. .
In this case, the charge of one of the separated electrons and holes reaches the corresponding electrode layer via the domain responsible for charge transport, but the other charge passes through the organic dye 23 film. , Move to the domain responsible for transport and reach the corresponding electrode layer.
In this way, the domain interface where the film of the organic dye 23 is formed thickly causes energy loss due to charge transfer inside the organic dye 23 as compared with the thinly formed portion.

  Next, the irradiation light H that has passed without being absorbed by the donor domain 21 enters the organic dye 23 and directly generates excitons inside the organic dye 23 (FIG. 2 (f)). The excitons generated in the organic dye 23 in this way are separated in charge without moving, and the generated electrons move to the conduction band of the negative electrode layer 12 via the LUMO of the acceptor domain 22, The generated holes move to the conduction band of the positive electrode layer 11 via the HOMO of the donor domain 21 (FIG. 2 (g)).

  As described above, since the organic dye 23 unevenly distributed at the domain interface is distributed thinly and uniformly, most of the excitons generated in the active layer 20 by absorbing the irradiation light are deactivated. It is involved in power generation with a high probability without charge separation.

(Second Embodiment)
As shown in the conceptual diagram of FIG. 3A, the photoelectric conversion element 10 ′ according to the second embodiment includes a positive hole transport layer 30 between the positive electrode layer 11 and the active layer 20, and the negative electrode layer 12 and the active layer. An electron transport layer 40 is disposed between the layers 20.
The thickness of the hole transport layer 30 or the electron transport layer 40 is preferably optimized depending on the material used. For example, when a conductive polymer such as PEDOT-PSS described later is used as the hole transport layer 30, the thickness is desirably 10 nm to 200 nm. When a metal oxide such as TiOx described later is used as the electron transport layer 40, the thickness is preferably 0.5 nm to 50 nm. This is because when the thickness is larger than the optimum film thickness, the internal resistance of the photoelectric conversion element 10 'increases and the characteristics deteriorate, and when it is thin, the thickness unevenness increases and the characteristics and quality become unstable.

The hole transport layer 30 preferably has a HOMO level between the conduction band level of the positive electrode layer 11 and the HOMO level of the donor domain 21 and a small gap interval. By configuring the hole transport layer 30 in this manner, holes from the active layer 20 can be smoothly moved to the positive electrode layer 11.
Substances used for the hole transport layer 30 include thiophene, ferrocene, paraphenylene vinylene, carbazole, pyrrole, aniline, diamine, phthalocyanine, and hydrazone functional groups, and V _2. Specific examples include metal oxides such as O ₅ , MoO ₃ , and NiO.

The electron transport layer 40 preferably has a LUMO level or a conduction band level between the conduction band level of the negative electrode layer 12 and the LUMO level of the acceptor domain 22 and a small gap interval. By configuring the electron transport layer 40 in this manner, electrons from the active layer 20 can be smoothly moved to the negative electrode layer 12.
Specific examples of the material used for the electron transport layer 40 include metal oxides such as TiOx, ZnO, and CsO, and derivatives such as bathocuproine, fullerene, oxadiazole, oxador, perylene, and naphthalene, and metal complexes. .

  The power generation principle of the photoelectric conversion element according to the second embodiment will be described with reference to FIG. In FIG. 3B, the hole transport layer 30 is mainly composed of PEDOT-PSS (see FIG. 6 as appropriate), the donor domain 21 is composed mainly of poly (3-hexylthiophene) (P3HT) as the donor molecule D, The organic dye 23 has a silicon phthalocyanine derivative (SiPc) as a main component, the acceptor domain 22 has a fullerene derivative (C61-PCBM) as a main component as an acceptor molecule A, and the electron transport layer 40 has a main component of TiOx. The energy level of each HOMO / LUMO / conduction band is expressed with the vacuum level as a reference (Evac = 0).

Here, by the irradiation light H, excitons are generated in the donor domain 21 (P3HT), in which HOMO electrons having an energy level of −5.1 eV are transitioned to LUMO having an energy level of −3.2 eV.
The excitons generated in the donor domain 21 transfer energy to the organic dye 23, and the HOMO electrons having an energy level of −5.2 eV are transitioned to LUMO having an energy level of −3.5 eV.
The electrons that have transitioned to LUMO (−3.5 eV) undergo charge separation at the domain interface, and then pass through the LUMO (−3.7 eV) of the acceptor domain 22 and the conduction band (−4.1 eV) of the electron transport layer 40. Thus, it reaches the negative electrode layer 12 of Al having a conduction band level of −4.3 eV.

  On the other hand, some excitons generated in the donor domain 21 convert the electrons transitioned to LUMO (−3.2 eV) into LUMO (−3.5 eV) of the organic dye 23 and LUMO (−3.7 eV) of the acceptor domain 22. ), The charge is transferred via the conduction band (−4.1 eV) of the electron transport layer 40 to reach the Al negative electrode layer 12 having a conduction band level of −4.3 eV.

By the irradiation light H, an exciton is generated in the organic dye 23 in which an electron of HOMO having an energy level of −5.2 eV transitions to LUMO having an energy level of −3.5 eV.
The electrons that have transitioned to LUMO (−3.5 eV) undergo charge separation at the domain interface, and then pass through the LUMO (−3.7 eV) of the acceptor domain 22 and the conduction band (−4.1 eV) of the electron transport layer 40. Thus, it reaches the negative electrode layer 12 of Al having a conduction band level of −4.3 eV.

The holes generated by the charge separation have a conduction band level of −4.5 eV via the HOMO (−5.1 eV) of the donor domain 21 and the HOMO (−5.0 eV) of the hole transport layer 30. It reaches the positive electrode layer 11 made of ITO.
As a result, a potential difference is generated between the pair of electrode layers 11 and 12 facing each other.

(Third embodiment)
As shown in the conceptual diagram of FIG. 4A, the photoelectric conversion element 10 ″ according to the third embodiment applies a transparent electrode (ITO) as the negative electrode layer 12 as an electrode layer disposed on both sides of the active layer 20. In this case, the applied positive electrode layer 11 uses Au (−5.2 eV) whose conduction band level is lower than ITO (−4.5 eV).
The configuration of the photoelectric conversion element 10 ″ according to the third embodiment is different from the photoelectric conversion element 10 ′ according to the second embodiment in that the hole transport layer 30 is omitted and the electrodes used for the positive electrode layer 11 and the negative electrode layer 12 are used. As described above, the description is common except that the combination of Au and ITO is applied instead of the combination of ITO and Al. Therefore, the description of the second embodiment is cited for the description of the power generation principle and the like of the photoelectric conversion element 10 ″. The description will be omitted.

By the way, in specific examples of the photoelectric conversion element 10 exemplified in the second and third embodiments, the values of LUMO level, HOMO level, and conduction band level obtained by electrochemical measurement or spectroscopic measurement are as follows: It does not necessarily have an ideal energy gradient.
However, in reality, even if it does not have such an ideal energy gradient, if the energy levels of HOMO and LUMO of two substances in contact via the domain interface are close, this domain interface is The electrons and holes move through.

(Configuration of solar cell)
FIG. 5 is an enlarged cross-sectional view showing an embodiment of the solar cell of the present invention. Here, as the photoelectric conversion element 10 ′ applied to the solar cell 50, the one described in the second embodiment is illustrated.
The solar cell 50 includes a transparent electrode substrate 13 as a support for the photoelectric conversion element 10 ′, wiring that is fixed to the terminal contacts 14, 14 on the positive electrode layer 11 and the negative electrode layer 12 and connected to the external load 26. Consists of The solar cell 50 photoelectrically converts the irradiation light H incident from the electrode substrate 13, guides the current to the external load 26, and causes the external load 26 to work.

The electrode substrate 13 may be anything as long as it transmits the irradiation light H without absorbing it and stably supports the photoelectric conversion element 10, and may be any transparent substrate such as glass or plastic. can do. In addition, an electrode layer (positive electrode layer 11) is provided on one surface of the electrode substrate 13 by a known method, but an ITO film deposited is commercially available and widely distributed.
In addition, the use of the photoelectric conversion element 10, 10 ', 10 "of this invention is not limited to the solar cell 50, For example, it can utilize also for uses, such as an optical sensor.

(Description of manufacturing method)
Next, an embodiment of a method for manufacturing a photoelectric conversion element according to the present invention will be described based on the process diagrams shown in FIGS. 6 (a), 6 (b), 7 (c), 7 (d), and 7 (e).
First, as shown in FIG. 6A, a hole transport layer 30 is formed on an ITO transparent electrode (positive electrode layer 11 in the figure) provided on a substrate by a known method. (In the case where the ITO transparent electrode is the negative electrode layer 12, the electron transport layer 40 is formed first.)
Next, the donor molecule D (P3HT) which is the main component of the donor domain 21, the acceptor molecule A (C61-PCBM) and the organic dye 23 (SiPc) which are the main components of the acceptor domain 22 are mixed in an organic solvent and stirred. A uniform mixed solution is prepared.
Here, 0.1 to 10 parts by weight of the organic dye 23 is added to the organic solvent with respect to 100 parts by weight of the donor molecule D and the acceptor molecule A in total.

  Here, when the compounding quantity of the organic pigment | dye 23 is more than 10 weight part, as FIG. 12 mentioned later shows, the electric power generation characteristic of a photoelectric conversion element will fall. This is presumably because the film of the organic dye 23 deposited on the domain interface becomes thick or agglomerated, so that the energy loss accompanying the charge transfer in the organic dye 23 increases as described above. Moreover, when the compounding quantity of the organic pigment | dye 23 is less than 0.1 weight part, it is thought that the ratio of the exciton which does not reach charge separation but is deactivated is not improved.

  Next, the prepared mixed solution is applied on the substrate of the hole transport layer 30 provided on the electrode substrate 13 (see FIG. 6B). As a method for applying the solution on the substrate in this way, a spin coating method is typified, but other known methods may be adopted.

Spin coating is a method in which a predetermined rotational speed is applied to the fixed electrode substrate 13, a mixed solution is dropped from above, and a liquid film is uniformly applied on the substrate by the action of centrifugal force.
Then, the electrode substrate 13 thus coated with the mixed solution is removed from the electrode substrate 13 in an atmosphere adjusted to a predetermined temperature, pressure, and non-oxidation property (desolvation), and the donor molecule D, the acceptor molecule A, and the organic material are removed. An organic thin film layer in which the dye 23 is mixed is obtained (FIG. 7C).

  In this organic thin film layer, as shown in FIG. 7C, an organic dye 23 (not shown) having a weak cohesive force is formed on an aggregate of fine aggregates of donor molecules D and acceptor molecules A formed by self-aggregation. It is thought that it is in a distributed state.

And in order to control the structure | tissue of the donor domain 21, the acceptor domain 22, and the organic pigment | dye 23 in the active layer 20, it heat-processes for a predetermined time by predetermined temperature in non-oxidizing atmosphere. The heat treatment is desirably performed at a temperature higher than the glass transition temperature of the donor molecule D and the acceptor molecule A.
Interfacial tension acts to reduce the interface free energy by making the interface as small as possible at the domain interface. As described above, when the mobility of the molecular chain is improved by setting the temperature higher than the glass transition temperature, adjacent masses of the same kind are connected to make the domain interface smaller, so that the donor domain 21 and the acceptor domain 22 are connected. Will grow.

  Due to such interfacial tension and cohesive force, as the donor domain 21 and the acceptor domain 22 grow, the dissolved organic dye 23 is preferentially deposited on the phase-separated domain interface. This is because the organic dye 23 (SiPc) is incompatible with P3HT and C61-PCBM constituting the domain and has a small self-aggregation property. As a result, a structure in which the organic dye 23 is unevenly distributed appears at the domain interface having a structure in which the donor domain 21 and the acceptor domain 22 are mixed in phase separation (FIG. 7D).

Finally, an electron transport layer 40 (a hole transport layer 30 when an ITO transparent electrode is used as the negative electrode layer 12) and a counter electrode (the negative electrode layer 12 in the figure) are formed to complete the photoelectric conversion element.
The electron transport layer 40 is provided by a known method in the same manner as the hole transport layer. The counter electrode can be produced by vapor-depositing a metal such as Al (FIG. 7E).

Hereinafter, with reference to FIGS. 6 to 17, an embodiment in which the effect of the present invention has been confirmed will be described.
<Preparation of hole transport layer 30>
The hole transport layer 30 is composed mainly of PEDOT-PSS, which is a complex of polyethylenedioxythiophene (PEDOT) and polystyrenesulfonic acid (PSS).

  A 1.0-1.4 wt% aqueous solution of PEDOT-PSS was cast on the surface of the ITO transparent electrode cleaned by sonication with toluene, acetone, and ethanol solutions for 15 minutes each, and spin-coated. The rotation speed was 400 rpm for the first 10 seconds and then 3000 rpm for 99 seconds. The solvent was removed by drying the polymer film obtained by this spin coating at 140 ° C. for 10 minutes to obtain a 40 nm-thick hole transport layer 30 (see FIG. 6A).

<Preparation of active layer 20>
Next, 10 mg of poly (3-hexylthiophene) (P3HT: poly (3-hexylthiophene)) as an acceptor molecule 22 as the main component of the acceptor domain 22 is added to 1 mL of chlorobenzene as the donor molecule D as the main component of the donor domain 21. 10 mg of fullerene derivative (C61-PCBM: phenyl-C61-butyric acid methyl ester) is added as A, and 0.7 mg of silicon phthalocyanine derivative (SiPc: silicon (IV) phthalocyanine bis (trihexylsilyloxide)) is added as organic dye 23 to obtain a uniform solution Got.

  This solution was cast on the surface of the hole transport layer 30 and spin coated. The rotation speed was 1200 rpm for 60 seconds. An organic thin film is obtained by this spin coating (FIG. 6B). When the obtained organic thin film is vacuum dried to remove the solvent, an organic thin film (FIG. 7C) in which SiPc is dispersed in an aggregate of P3HT microcrystals and C61-PCBM microcrystals is obtained. Next, when annealing (heat treatment) is performed at 150 ° C. for 30 minutes in a nitrogen atmosphere, the microcrystals are connected and grow to form domains 21 and 22, and SiPc is deposited at the interface (FIG. 7D). ).

<Preparation of Electron Transport Layer 40>
Next, a solution obtained by diluting titanium isopropoxide 100 times with dehydrated ethanol is spin-coated on the surface of the active layer 20 under the condition of 4000 rpm for 60 seconds, and stored overnight in a cool and dark place in the atmosphere. A TiOx layer is obtained as the electron transport layer 40 by the gel method (FIG. 7E).

<Preparation of counter electrode 12>
Aluminum was vapor-deposited on the electron carrying layer 40 using the vacuum evaporation apparatus, and it was set as the counter electrode. The conditions were as follows: vapor deposition was performed at a vapor deposition rate of <1 nm · s ⁻¹ for 400 seconds to obtain an aluminum electrode layer 12 having a thickness of 70 nm (FIG. 7E).
As described above, the photoelectric conversion element according to the example was manufactured (see FIG. 3).

<Comparative Example 1>
Next, as Comparative Example 1, a photoelectric conversion element in which annealing treatment was not performed as compared with the Example was manufactured.
Let the organic thin film produced by the same method as an example (Drawing 7 (c)) be an active layer concerning comparative example 1. The electron transport layer 40 and the counter electrode 12 are produced without performing annealing treatment on this, and the photoelectric conversion element according to Comparative Example 1 is obtained (FIG. 7F).

<Comparative example 2>
Next, as Comparative Example 2, a photoelectric conversion element in which the organic dye 23 was not included and annealing treatment was not performed as compared with the Example was manufactured.
On the hole transport layer 30 of the electrode substrate produced by the same method as in the example, a solution was applied by the same method except that SiPc was not blended (FIG. 6 (b ′)), and the solvent was volatilized. An active layer according to Comparative Example 2 is obtained (FIG. 8 (c ′)). The electron transport layer 40 and the counter electrode 12 are produced without performing annealing treatment on this, and the photoelectric conversion element according to Comparative Example 2 is obtained (FIG. 8 (f ′)).

<Comparative Example 3>
Next, as Comparative Example 3, a photoelectric conversion element in which the organic dye 23 was not included as compared with the Example but was annealed was produced.
The active layer according to Comparative Example 2 (FIG. 8 (c ′)) is annealed to obtain an active layer according to Comparative Example 3 (FIG. 8 (d ′)), and further, the electron transport layer 40 and the counter electrode 12 are obtained. To obtain a photoelectric conversion element according to Comparative Example 3 (FIG. 8 (e ′)).

<Comparative example 4>
Next, as Comparative Example 4 (see FIG. 14), a zinc phthalocyanine derivative (ZnPc) having no axial ligand is used as an organic dye instead of SiPc as compared with the Example, and annealing treatment is not performed. An active layer was prepared. This ZnPc has the property of being more cohesive than SiPc because it does not have an axial ligand.
A solution containing ZnPc instead of SiPc was applied on the hole transport layer 30 of the electrode substrate produced by the same method as in the example (FIG. 14 (b ″)), and the solvent was volatilized for comparison. 4 is obtained (FIG. 14 (c ″)). The electron transport layer 40 and the counter electrode 12 are produced without performing annealing treatment on this, and the photoelectric conversion element according to Comparative Example 4 is obtained (FIG. 14 (f ″)).

<Comparative Example 5>
Next, as Comparative Example 5, an active layer was produced in the case where ZnPc having high cohesiveness was employed instead of SiPc as an organic dye as compared with the Example.
The organic thin film according to Comparative Example 4 (FIG. 14C ″) is annealed to obtain an active layer according to Comparative Example 5 (FIG. 14D ″). The electron transport layer 40 and the counter electrode 12 are produced without performing annealing treatment on this, and the photoelectric conversion element according to Comparative Example 5 is obtained (FIG. 14 (e ″)).

<Results of comparative study>
FIG. 9 is a measurement graph of absorbance for each wavelength of irradiation light in the active layers according to Examples and Comparative Examples 1, 2, and 3.
This measurement result of absorbance is a result of ultraviolet-visible light passing through an active layer provided on the transparent substrate 11 to obtain an ultraviolet-visible absorption spectrum, and then subtracting the spectrum of only the transparent substrate 11 later.

The absorption band of 400 to 650 nm in the absorbance measurement graph (FIG. 9) is derived from P3HT, and the sharp peak-shaped absorption band of 670 nm is derived from SiPc. Although scaled out, an absorption band derived from C61-PCBM is observed in the vicinity of 340 nm.
From this, it is observed that the absorbance derived from SiPc does not change, but the absorbance derived from P3HT is improved by performing the annealing treatment. This is because the crystal structure of SiPc does not change by annealing, but amorphous (amorphous) crystallizes in P3HT.

FIG. 10 is a measurement graph of a JV curve under irradiation of simulated sunlight in the photoelectric conversion elements according to Examples and Comparative Examples 1, 2, and 3.
A 500 W xenon lamp was used as the irradiation light source, and 100 mW · cm ⁻² , AM1.5G artificial sunlight (light rays) was irradiated from the ITO substrate side.
As is clear by comparing the results of Comparative Example 1 and Comparative Example 2, the short-circuit current density is about 1.8 mA · cm ⁻² regardless of the presence or absence of SiPc when annealing is not performed. Was not observed.
However, the short circuit current density if SiPc formulation is not by performing the annealing treatment was increased to 6.2 mA · ^{cm -2,} if further blended with SiPc short-circuit current density increases until 8.0 mA · ^{cm -2} .

FIG. 11 is a measurement graph of external quantum yield (EQE) with respect to each wavelength of irradiation light in the photoelectric conversion elements according to Examples and Comparative Examples 1, 2, and 3.
From this measurement result, by performing the annealing treatment, the EQE spectrum derived from SiPc is improved, and the improvement of the EQE spectrum derived from P3HT is also observed.
Then, it can be said that the degree of improvement in the EQE spectrum derived from P3HT due to this annealing treatment is more remarkable than the degree of improvement in the absorption spectrum in FIG.
This confirms that a structure in which the donor domain 21 of P3HT grown by crystallization and the acceptor domain 22 of C61-PCBM are phase-separated and mixed is formed. That is, it is presumed that charges (electrons and holes) after charge separation at the domain interface can smoothly reach the corresponding electrode layer without being inhibited by the other domain interface.
Further, from the comparison between the annealed example and the comparative example 3, the improvement in the EQE spectrum derived from P3HT is observed in the example in which the SiPc is blended compared to the unblended comparative example 3. On the other hand, in Comparative Examples 1 and 2 where annealing has not been performed, the presence or absence of SiPc is irrelevant to the change in the EQE spectrum derived from P3HT.

FIG. 15 is a measurement graph of absorbance for each wavelength of irradiated light in the active layers according to Comparative Examples 2, 3, 4, and 5.
From the measurement results of Comparative Examples 4 and 5 containing ZnPc as an organic dye, it can be said that when ZnPc having high cohesiveness is applied, the intensity of the light absorption spectrum near 670 nm derived from this organic dye is extremely weak.

Although the description of the measurement results is omitted, when an absorption spectrum is observed by re-dissolving the active layer containing ZnPc in a solvent, a high-intensity spectrum derived from ZnPc is detected in the vicinity of 670 nm. ZnPc is definitely present in the active layer.
When the organic thin film is formed in this manner, the absorption spectrum derived from ZnPc disappears because the ZnPc added as an organic dye aggregates inside the active layer to form a lump and is locally scattered. This is thought to be because the effective area incident on the organic dye was substantially reduced.

  On the other hand, when examining the absorption spectra (FIG. 9) of Examples and Comparative Example 1 in which SiPc having low cohesiveness is used as the organic dye, the absorption spectra derived from SiPc were observed with the same intensity regardless of the presence or absence of annealing treatment. Has been. From this, when SiPc having low cohesion is adopted as the organic dye, the effective area where the irradiated light enters the organic dye does not substantially change even after annealing, and the amount of excitons generated is the same. It is shown that.

FIG. 16 is a measurement graph of a JV curve under irradiation with simulated sunlight in the photoelectric conversion elements according to Comparative Examples 2, 3, 4, and 5.
When the results of Comparative Example 4 and Comparative Example 5 are compared, even when ZnPc is blended, an increase in short-circuit current density is observed by performing the annealing treatment, but when no organic dye is blended (Comparative Example 2 → Comparison Its effectiveness is inferior to that of Example 3).

FIG. 17 is a measurement graph of external quantum yield (EQE) for each wavelength of irradiation light in the photoelectric conversion elements according to Comparative Examples 2, 3, 4, and 5.
From a comparison of the results of Comparative Example 4 and Comparative Example 5, even when ZnPc is used as the organic dye, an improvement in the EQE spectrum derived from P3HT is observed by performing the annealing treatment. However, the result that the intensity | strength of the improved EQE spectrum was weaker than the case where an organic pigment | dye is not mix | blended (comparative example 2-> comparative example 3) was obtained.
That is, when ZnPc having high cohesiveness is employed as the organic dye, it does not contribute to the improvement of the characteristics of the photoelectric conversion element, but decreases. This is presumably because ZnPc aggregated in a lump shape by annealing treatment further grows and inhibits the smooth movement of charges separated at the domain interface.

Next, an example in which SiPc having an axial ligand as a functional group and suppressed cohesiveness is employed as an organic dye will be examined.
In the measurement results of the example of FIG. 11 and the comparative example 1, the EQE spectrum intensity derived from SiPc is increased by the annealing treatment. Therefore, in the Example, it has shown that the electric current generation by the light absorption of the organic pigment | dye (SiPc) increased by annealing treatment.
This is because, in the absorption spectrum derived from SiPc (FIG. 9), there was no change in intensity due to the presence or absence of annealing treatment, and thus the exciton generated in SiPc is deactivated when annealing treatment is not performed. Means high.
That is, it is suggested that when annealing is performed, excitons generated in the organic dye (SiPc) undergo charge separation in situ, and the generated holes and electrons move quickly to P3HT and C61-PCBM, respectively. ing. From this measurement result, it is confirmed that when annealing is performed, SiPc precipitates at the domain interface and is widely distributed thinly.

Furthermore, from the comparison between the example in FIG. 11 and the comparative example 3, in the photoelectric conversion element that has been annealed, an improvement in photocurrent in the absorption spectrum derived from P3HT is also observed due to the SiPc compounding. . From this, when SiPc is not blended, the rate of deactivation is high even if excitons are generated in P3HT, but by incorporating SiPc, excitons are efficiently collected at the domain interface, leading to charge separation. This suggests that the proportion will increase.
That is, due to the relationship between the HOMO-LUMO Eg (1.7 eV) of SiPc and the Eg (1.9 eV) of P3HT (see FIG. 3), the absorption spectrum of SiPc and the emission spectrum of P3HT overlap well. This confirms that even P3HT excitons generated at a position far from the domain interface excite SiPc after energy transfer over a long distance to the domain interface to separate charges.

  From the above measurement results, when annealing is performed, a domain structure in which P3HT and C61-PCBM are two-phase separated and mixed is formed, and SiPc is precipitated and a structure that is unevenly distributed at the domain interface is formed. I support that. Thus, SiPc is unevenly distributed at the domain interface of P3HT and C61-PCBM because when P3HT and C61-PCBM, which have high crystallinity, undergo domain growth by crystallization, both phases of P3HT and C61-PCBM This is probably because SiPc precipitates and gathers at the interface.

12 and Table 1 measure the J-V curve under simulated sunlight irradiation by changing the blending amount of the organic dye (SiPc) in the photoelectric conversion element (FIG. 7 (e)) according to the example. The measured values of short-circuit current density (Jsc), fill factor (FF), and energy conversion efficiency (η) are shown. For reference, measured values of the photoelectric conversion element according to Comparative Example 5 are also appended.
In the measurement, the weight ratio of the donor molecule (P3HT) and the acceptor molecule (C61-PCBM) is 1: 1, and the relative weight of SiPc blended with respect to 100 parts by weight of P3HT and C61-PCBM is 0, A photoelectric conversion element provided with an active layer changed to 0.5, 1.5, 3.5, and 10 parts by weight was prepared. The EQE spectra of 0 parts by weight and 3.5 parts by weight are the results corresponding to Comparative Example 3 and Example in FIGS.

  From FIG. 12 and Table 1, from 0 to 3.5 parts by weight, various performances of short-circuit current density (Jsc) and energy conversion efficiency (η) improve as the blending amount of the organic dye (SiPc) increases. On the other hand, when it exceeds 3.5 parts by weight, various performances decrease as the blending amount increases, and when it exceeds 10 parts by weight, the energy conversion efficiency (η) becomes worse than the case of 0 part by weight. From this, the knowledge that the organic dye (SiPc) improves the characteristics of the photoelectric conversion element is obtained within a range where the blending amount does not exceed 10 parts by weight.

FIG. 13 is a measurement graph of external quantum yield (EQE) with respect to each wavelength of irradiation light in the photoelectric conversion element according to the example in which the blending amount of the organic dye (SiPc) shown in Table 1 is changed.
According to the measurement result of FIG. 13, the intensity of the EQE spectrum derived from the organic dye (SiPc) is improved corresponding to the amount of SiPc. On the other hand, it is understood that the intensity of the EQE spectrum derived from the donor molecule (P3HT) has a maximum value with respect to the amount of SiPc. This is considered to be because the distribution area of SiPc occupying the domain interface increases as the amount of SiPc increases until the EQE spectrum shows a maximum value. On the other hand, after the EQE spectrum exceeds the maximum value, the SiPc film becomes thicker as the SiPc content increases, and it is considered that the energy loss due to charge transfer through the film increases.

  From the above measurement results, it is clear that the performance of the solar cell is improved when absorption of the dye added to the light absorption spectrum of the active layer is observed.

(A) is a conceptual diagram which shows 1st Embodiment of the photoelectric conversion element of this invention, (b) is explanatory drawing of the electric power generation principle. It is the elements on larger scale which expand and show the boundary part of the domain which constitutes the active layer of the photoelectric conversion element concerning this embodiment. (A) is a conceptual diagram which shows 2nd Embodiment of the photoelectric conversion element of this invention, (b) is explanatory drawing of the electric power generation principle. (A) is a conceptual diagram which shows 3rd Embodiment of the photoelectric conversion element of this invention, (b) is explanatory drawing of the electric power generation principle. (A) is an expanded sectional view which shows embodiment of the solar cell of this invention. (A) (b) is a conceptual diagram which shows embodiment of the application | coating process in the manufacturing method of the photoelectric conversion element of this invention, Comprising: The molecular structural formula of an organic pigment | dye (SiPc) and another component is illustrated. Further, (b ′) shows the molecular structural formulas of the constituent components of the comparative example. (C) (d) is a conceptual diagram which shows embodiment of the heat processing process in the manufacturing method of the photoelectric conversion element of this invention, Comprising: (e) has shown the same photoelectric conversion element as Fig.3 (a). Also, (f) shows a comparative example 1 in which a photoelectric conversion element is manufactured by omitting the annealing process from the stage of FIG. (C ′), (d ′), and (e ′) show, as Comparative Example 3, a process of manufacturing a photoelectric conversion element through an annealing process from the stage of FIG. Further, (f ′) shows a comparative example 2 in which a photoelectric conversion element is manufactured by omitting the annealing process from the stage of FIG. In the active layer which concerns on an Example and Comparative Examples 1, 2, 3, it is a measurement graph of the light absorbency with respect to each wavelength of irradiated light. In the photoelectric conversion element which concerns on an Example and Comparative Examples 1, 2, and 3, it is a measurement graph of the JV curve under pseudo-sunlight irradiation. In the photoelectric conversion element which concerns on an Example and Comparative Examples 1, 2, and 3, it is a measurement graph of the external quantum yield (EQE) with respect to each wavelength of irradiation light. In the photoelectric conversion element according to the example, the short-circuit current density (Jsc), fill factor (FF), energy conversion efficiency (η) of the JV curve under simulated sunlight irradiation measured by changing the blending amount of the organic dye ) Measured value. In the photoelectric conversion element which concerns on an Example, it is a measurement graph of the external quantum yield (EQE) with respect to each wavelength of irradiation light at the time of changing the compounding quantity of an organic pigment | dye. (B ″) (c ″) (d ″) (e ″) are photoelectric conversions in the case where an organic dye (ZnPc) having no axial ligand is used as Comparative Examples 4 and 5, unlike the examples. The device fabrication process is shown. Further, (f ″) shows a comparative example 4 in which a photoelectric conversion element was manufactured by omitting the annealing process from the stage of FIG. 14 (c ″). In the active layer which concerns on the comparative examples 2, 3, 4, and 5, it is a measurement graph of the light absorbency with respect to each wavelength of irradiated light. In the photoelectric conversion element which concerns on the comparative examples 2, 3, 4, and 5, it is a measurement graph of the JV curve under pseudo-sunlight irradiation. In the photoelectric conversion element concerning the comparative examples 2, 3, 4, and 5, it is a measurement graph of the external quantum yield (EQE) with respect to each wavelength of irradiation light.

Explanation of symbols

10, 10 ', 10 "photoelectric conversion element 11 positive electrode layer (electrode layer)
12 Negative electrode layer (electrode layer)
20 Active layer 21 Donor domain (first domain)
22 Acceptor domain (second domain)
23 organic dye 30 hole transport layer 40 electron transport layer 50 solar cell A acceptor molecule D donor molecule H irradiation light R axis ligand R ′ substituent

Claims (11)

A photoelectric conversion element that generates a potential difference between a pair of electrode layers disposed opposite to both sides of an active layer when irradiated with light,
The active layer is
A bulk heterojunction structure in which a first domain that absorbs the irradiated light to donate excited electrons and a second domain that accepts the electrons are mixed;
The organic dye is excited by absorbing the irradiation light, you are unevenly distributed in the interface between the first domains bulk heterojunction with said second domain
The photoelectric conversion device characterized and this. The organic dye, a functional group that inhibits overlap of π-conjugated molecular orbital adjacent to each other including
The photoelectric conversion device according to claim 1, wherein the this. The organic dye is Ru complex der with which can take a non-planar coordination geometry atoms
The photoelectric conversion device according to claim 2, wherein the this. Absorption peak of light absorption spectrum of the organic dye, located on the longer wavelength side than the absorption peak of the first domain or the second domain
The photoelectric conversion device according to any one of claims 1 to 3, characterized and this. HOMO level of the organic dye is lower than the HOMO level of the donor molecule to function the first domain, and higher than the HOMO level of the acceptor molecule to function the second domain,
The LUMO level of the organic dye is lower than the LUMO level of the donor molecule and higher than the LUMO level of the acceptor molecule,
HOMO-LUMO gap of the organic dyes, have smaller than that of said donor molecules
The photoelectric conversion device according to any one of claims 1 to 4, characterized and this.   The organic dye is a metal porphyrin having an axial ligand, a metal phthalocyanine, or a metal naphthalocyanine
The photoelectric conversion element according to any one of claims 1 to 5, wherein the photoelectric conversion element is provided.   The organic dye has a chemical formula

Is represented by
The photoelectric conversion element according to any one of claims 1 to 6, wherein the photoelectric conversion element is characterized. At least one of the hole transport layer and the electron transport layer is Ru disposed between the electrode layer and the active layer
The photoelectric conversion device according to any one of claims 1 to 7, characterized and this. Comprising a photoelectric conversion device according to any one of claims 1 to 8, Ru is the work to the external load coupled
A solar cell characterized by that . Ultraviolet said active layer - visible - Ru least part of the light absorption spectra of an organic dye as measured near-infrared light absorption spectrum is observed
The photoelectric conversion device according to claim 1, wherein the this. A method for producing a photoelectric conversion element in which a potential difference is generated between a pair of electrode layers disposed opposite to both sides of an active layer when irradiated with light,
A solution is prepared by dissolving a total of 100 parts by weight of a donor molecule that absorbs the irradiated light and donates excited electrons and an acceptor molecule that accepts the electrons and 0.1 to 10 parts by weight of an organic dye in a solvent. Stages,
Applying the solution onto a substrate provided with one of the electrode layers and volatilizing the solvent;
The interface between the first domain and said acceptor is molecular second domain phase separation consisting of expressing the structure of bulk heterojunction type mixed with Rutotomoni, the second domain and the first domain that bulk heterojunction composed of the donor molecule wherein said forming said active layer an organic dye is unevenly distributed, to,
The organic dye is
The HOMO-LUMO gap is smaller than that of the donor molecule ,
HOMO level lower than the HOMO level of the donor molecules, and is higher than the HOMO level of the acceptor molecule,
The LUMO level is lower than the LUMO level of the donor molecule and higher than the LUMO level of the acceptor molecule ;
Wherein and a donor molecule and incompatible with respect to the acceptor molecule self cohesion than these is less
Method of manufacturing a photoelectric conversion element characterized and this.

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