Platinum complex and thin-film solar cell using the same

Abstract

To solve the problem in which, in an active layer of a thin-film solar cell, a p-type semiconductor and an n-type semiconductor are dissolved in a solvent to construct a bulk hetero-domain structure, thereby preventing recombination of carriers, however, it is not easy to control the size of the domain structure, and thus high efficiency has not been achieved.SOLUTION: A platinum complex such as a compound (5) represented by formula (5), in which a donor unit containing a thiophene skeleton and an acceptor unit coexist, is capable of preventing recombination of carriers in an active layer due to the presence of a heavy metal.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a platinum complex and a thin-film solar cell using the platinum complex as an acceptor. [Background technology]

[0002] Organic thin-film solar cells (OLEDs) are environmentally friendly, lightweight, and flexible solar cells that can be mass-produced inexpensively using low-temperature printing processes such as roll-to-roll on plastic substrates, and are expected to be used in a wide range of applications as ubiquitous power sources. These thin-film solar cells have an active layer made from a combination of p-type organic semiconductors (donor molecules or polymers) and n-type semiconductors (acceptor molecules or polymers). Various p-type and n-type organic semiconductors have been developed to improve their efficiency.

[0003] Generally, fullerene (C60) derivatives, such as PCBM, have been used as n-type semiconductors, but thin-film solar cells using non-fullerene acceptors, which are n-type semiconductors that are not fullerene (C60) derivatives, have been found to exhibit high photoelectric conversion properties and have attracted attention in recent years.

[0004] This is because the fullerene derivatives that have been mainly used in this field to date have low optical absorption properties in the visible region, and the acceptor layer has not directly contributed to the generation of carriers through optical absorption, whereas non-fullerene acceptors exhibit strong optical absorption properties in the visible region.

[0005] Therefore, in recent years, acceptor molecules with strong absorption in the visible region have been used instead of fullerene derivatives. As a result, thin-film solar cells showing high photoelectric conversion performance exceeding 19% have been reported recently, and research into organic thin-film solar cells has become increasingly active (e.g., Patent Document 1). However, solar cell materials exceeding 10% are very limited, and their photoelectric conversion performance still falls short of that of currently popular silicon solar cells. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2018-98517 Summary of the Invention [Problem to be solved by the invention]

[0007] Organic thin-film solar cells are formed by simultaneously dissolving a p-type semiconductor, which exhibits donor properties, and an n-type semiconductor, which exhibits acceptor properties, in an organic solvent such as chlorobenzene, and then applying the solution to a substrate using a method such as spin coating. When the p-type and n-type semiconductors form a domain structure of several tens of nanometers in size called a bulk heterodomain structure, the recombination of generated carriers is suppressed, resulting in high efficiency.

[0008] Therefore, controlling the domain size is the biggest challenge, but at present it is not possible to know what kind of domain structure will be formed without actually applying a solution of p-type and n-type semiconductors, which makes the development of organic thin-film solar cells difficult. [Means for solving the problem]

[0009] Although it is very difficult to control the structure of the bulk heterodomain, the addition of heavy metal ions is one of the possible methods to suppress carrier recombination. That is, materials containing heavy metals tend to have a higher dielectric constant than materials made of only organic substances. In semiconductors with this large dielectric constant, the Coulomb force acting between holes and electrons is weaker, which reduces the recombination of carriers. Therefore, the present invention provides a semiconductor material (platinum complex), and also provides a thin-film solar cell using the same.

[0010] More specifically, the semiconductor material according to the present invention is characterized by having a platinum complex using a ligand in which a donor unit and an acceptor unit containing a thiophene skeleton coexist, and the thin-film solar cell according to the present invention is characterized by using the platinum complex as an n-type semiconductor. [Effects of the Invention]

[0011] As shown in the examples, the thin-film solar cell using the platinum complex of the present invention as an acceptor has an extremely high open-circuit voltage V of 1.06 V. OC Some of these have shown promise, suggesting that they may be able to provide thin-film solar cells with high photoelectric efficiency. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram showing a synthesis procedure for a platinum complex according to the present invention. [Figure 2] FIG. 1 is a diagram showing a synthesis procedure for a platinum complex according to the present invention. [Figure 3] FIG. 1 is a diagram showing a synthesis procedure for a platinum complex according to the present invention. [Figure 4] FIG. 1 is a diagram showing photoelectric effect characteristics when compound (2) is used. [Figure 5] FIG. 1 is a diagram showing photoelectric effect characteristics when compound (5) is used. [Figure 6] FIG. 1 is a diagram showing photoelectric effect characteristics when compound (9) is used. [Figure 7] FIG. 1 is a diagram showing photoelectric effect characteristics when compound (12) is used. DETAILED DESCRIPTION OF THE INVENTION

[0013] The thin-film solar cell according to the present invention will be described below with reference to the drawings and examples. Note that the following description exemplifies one embodiment of the present invention and one example, and the present invention is not limited to the following description. The following description can be modified within the scope of the present invention.

[0014] <Basic framework> The platinum complex according to the present invention is a complex using platinum as a heavy metal ion for suppressing carrier recombination, and has the following six types of basic structures.

[0015] [ka]

[0016] Here, R1 has the following structures R1_1 to R1_12.

[0017] [ka]

[0018] In addition, including Types 1 to 6, X represents hydrogen and halogen elements (H, F, Cl, Br, I), and R2 and R3 represent alkyl groups where n is 0 to 18.

[0019] The platinum complex according to the present invention has a ligand in which a donor unit (the portion indicated by "D" in the structural formula above, hereinafter referred to as "donor unit D") containing a thiophene skeleton and an acceptor unit (the portion indicated by "A" in the structural formula above, hereinafter referred to as "acceptor unit A") coexist. The donor unit and the acceptor unit are described in detail below.

[0020] <Donor Unit D> The donor unit D includes the following structures DU1 to DU41.

[0021] [ka]

[0022] [ka]

[0023] [ka]

[0024] [ka]

[0025] Here, R4 includes the following 12 structures, DR4_1 to DR4_12.

[0026] [ka]

[0027] In the compounds DU1 to DU41, X represents hydrogen and halogen elements (H, F, Cl, Br, I), and R5 and R6 represent alkyl groups where n is 0 to 18.

[0028] <Acceptor Unit A> The acceptor unit A contains 43 structures from AU1 to AU43.

[0029] [ka]

[0030] [ka]

[0031] [ka]

[0032] [ka]

[0033] [ka]

[0034] In addition, in AU1 to AU43, R7 and R8 include 12 structures, AR78_1 to AR78_12.

[0035] [ka]

[0036] Including AU1 to AU43, X1, X2, X3, and X4 represent hydrogen and halogen elements (H, F, Cl, Br, and I), and R9 and R 10 represents an alkyl group where n is 0 to 18.

[0037] Furthermore, A1 in AU1 to AU43 includes seven structures, AA1_1 to AA1_7.

[0038] [ka]

[0039] Furthermore, in the structures AA1_1 to AA1_7, R7 and R8 include 12 structures AA1R78_1 to AA1R78_12.

[0040] [ka]

[0041] Including AA1_1 to AA1_7, X1, X2, X3, and X4 represent hydrogen and halogen elements (H, F, Cl, Br, and I), and R9 and R 10 represents an alkyl group where n is 0 to 18.

[0042] The platinum complex according to the present invention can be used as an acceptor, mixed with a donor compound, and utilized in a thin-film solar cell. [Example]

[0043] In this study, a platinum complex coordinated with an acetylene derivative in which a donor unit containing a thiophene skeleton and an acceptor unit used for a non-fullerene acceptor coexist was newly synthesized, and its electronic state and physical properties were evaluated. In addition, an organic thin-film solar cell using these platinum complexes as an n-type semiconductor (acceptor) was fabricated, and its photoelectric conversion characteristics were evaluated.

[0044] Figure 1 shows the synthesis schemes of platinum complexes PtTIC and PtT2IC.

[0045] <Synthesis of trans-[Pt(ThCHO)2(PBu3)2] (ThCHO = 5-ethynylthiophene-2-carbaldehyde, referred to as compound (1)).> 5-Ethynylthiophene-2-carbaldehyde (333 mg, 2.45 mmol, 4 eq.) with deprotected trimethylsilyl group, tans-[PtCl2(PBu3)2] (411 mg, 0.613 mmol, 1 eq.), and CuI (6 mg, 0.03 mmol, 0.05 eq.) were added to a eggplant flask and purged with N2 for 15 minutes. Then dehydrated CH2Cl2 (10 mL) and NEt3 (10 mL) were added in sequence and stirred at room temperature for 15 minutes. 50 mL of H2O was added to quench the reaction, extracted with CH2Cl2, dehydrated with MgSO4, and concentrated using an evaporator. The crude product was purified by a silica gel column with 3 wt% NEt3 added to obtain pale yellow crystals in a yield of 90% (480 mg).

[0046] <Synthesis of trans-[Pt(Th-inden)2(PBu3)2] (Th-indene = 2-(2-((5-ethynylthiophen-2-yl)methylene)-3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile, referred to as PtTIC, compound (2)).> trans-[Pt(ThCHO)2(PBu3)2] (460 mg, 0.529 mmol, 1 eq.) and 2-(3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile (512 mg, 2.64 mmol, 5 eq.) were added to a two-neck flask and the mixture was purged with N2 for 15 min. Anhydrous CHCl3 (50 mL) was then added to dissolve the mixture, and pyridine (0.5 mL) was added at room temperature. The reaction solution immediately turned dark red and became blue after heating at 60 °C overnight.

[0047] 30 mL of EtOH was added to this reaction solution, and the chloroform alone was concentrated using a rotary evaporator. After filtration, a deep blue crystal was obtained in an 84% yield (542 mg). This compound was then dissolved in CHCl3 and gently added MeOH in a glass tube to obtain crystals suitable for single-crystal X-ray structural analysis. The structure of compound (2) is shown below.

[0048] [ka]

[0049] <Synthesis of 5-((trimethylsilyl)ethynyl)thieno[3,2-b]thiophene-2-carbaldehyde (referred to as compound (3))> 5-bromothieno[3,2-b]thiophene-2-carbaldehyde (1.61 g, 6.52 mmol, 1 eq.), CuI (62 mg, 0.33 mol, 0.05 eq.), and PdCl2(PPh3)2 (114 mg, 0.163 mmol, 0.025 eq.) were added to a recovery flask and the atmosphere was purged with N2 for 15 minutes. Then, THF (40 mL) and NEt3 (20 mL) were added, followed by TMSA (0.99 mL, 7.17 mmol, 1.1 eq.), and the mixture was stirred overnight at room temperature in the dark. The solution was then diluted with HO (60 mL). ) was added to quench the reaction, and extraction was carried out using ethyl acetate. After dehydration with MgSO4, it was concentrated using a rotary evaporator. This crude product was purified using silica gel chromatography to obtain white crystals with a yield of 64% (1.10 g). Subsequently, deprotection was carried out using a mixed solvent of 2 M KOH, CHCl3, and MeOH (crude yield 98%). Since the deprotected intermediate was air-unstable, it was used in the next reaction without further purification and analysis.

[0050] <Synthesis of trans-[Pt(TTCHO)2(PBu3)2] (TTCHO = 5-ethynylthieno[3,2-b]thiophene-2-carbaldehyde, referred to as compound (4).)> 5-Ethynylthieno[3,2-b]thiophene-2-carbaldehyde (658 mg, 3.42 mmol, 4 eq.) with the trimethylsilyl group deprotected, tans-[PtCl2(PBu3)2] (574 mg, 0.856 mmol, 1 eq.), and CuI (8 mg, 0.04 mmol, 0.05 eq.) were added to a eggplant flask and purged with N2 for 15 minutes. Then, dehydrated CH2Cl2 (15 mL) and NEt3 (9 mL) were added in sequence and stirred at room temperature for 15 minutes. After adding 50 mL of H2O to quench the reaction, extraction was carried out with CH2Cl2, followed by dehydration with MgSO4 and concentration using an evaporator. The crude product of this crude was purified using a silica gel column with 3 wt% NEt3 added to obtain pale yellow crystals with a yield of 81% (681 mg).

[0051] <Synthesis of trans-[Pt(TT-inden)2(PBu3)2] (TT-indene = 2-(2-((5-ethynylthieno[3,2-b]thiophen-2-yl)methylene)-3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile) (PtTTIC: referred to as compound (5).)> trans-[Pt(TTCHO)2(PBu3)2] (200 mg, 0.204 mmol, 1 eq.) and 2-(3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile (198 mg, 1.02 mmol, 5 eq.) were added to a two-neck flask and the atmosphere was flushed with N2 for 15 min. Anhydrous CHCl3 (30 mL) was then added to dissolve the mixture, and pyridine (0.3 mL) was added at room temperature. The reaction solution immediately turned dark red, but after heating at 60 °C overnight, it became blue. 30 mL of EtOH was added to the reaction solution, and the chloroform was concentrated on a rotary evaporator. After filtration, dark green crystals were obtained in 75% yield (203 mg). This compound was also dissolved in CHCl3 and gently added MeOH in a glass tube to obtain crystals suitable for single-crystal X-ray structural analysis. The structure of compound (5) is shown below.

[0052] [ka]

[0053] <Synthesis of 4,4'-bis(4-dodecylthiophen-2-yl)-2,2'-bipyridine (referred to as compound (6))> Next, with reference to Figure 2, the synthesis of Compound 9 from Compound 6 will be described. 4,4'-dibromo-2,2'-bipyridine (0.966 mg, 3.07 mmol, 1 eq.), tributyl(4-dodecylthiophen-2-yl)stannane (10 g, 18.46 mmol, 6 eq.), PdCl2(PPh3)2 (108 The reaction mixture (200 mg, 0.153 mmol, 0.05 eq.) was added to a three-neck flask and the atmosphere was purged with N2 for 15 minutes. Toluene (20 mL) was then added and the mixture was stirred overnight at 120 °C. The reaction solution was concentrated using a rotary evaporator and purified using a silica gel column containing 3 wt% NEt3, yielding a pale yellow precipitate in 98% yield (1.97 g).

[0054] <Synthesis of 4,4'-bis(4-dodecyl-5-(tributylstannyl)thiophen-2-yl)-2,2'-bipyridine (referred to as compound (7))> 4,4'-bis(4-dodecylthiophen-2-yl)-2,2'-bipyridine (500 mg, 0.761 mmol, 1 eq.) was added to a recovery flask and the mixture was purged with N2 for 15 minutes. Then, anhydrous THF (35 mL) was added and LDA (1.67 mL, 1.67 mmol, 2.2 eq.) was added dropwise at -78 °C, followed by stirring at -78 °C for 1 hour. After 1 hour, tributylchlorostannane (742 mg, 2.28 mmol, 3 eq.) was added and the mixture was allowed to warm to room temperature while stirring overnight. The reaction was quenched by the addition of H2O (30 mL), extracted with hexane, dehydrated with MgSO4, and concentrated using an evaporator. The crude product was purified using a silica gel column containing 3 wt% NEt3 to give a clear oil in 98% yield (921 mg).

[0055] <Synthesis of 2,2'-((([2,2'-bipyridine]-4,4'-diylbis(3'-dodecyl-3-hexyl-[2,2'-bithiophene]-5',5-diyl))bis(methaneylylidene))bis(3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile (BPIC; referred to as compound (8))> 4,4'-bis(4-dodecyl-5-(tributylstannyl)thiophen-2-yl)-2,2'-bipyridine (347 mg, 0.281 mmol, 1 eq.), 2-(2-((5-bromo-4-hexylthiophen-2-yl)methylene)-3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile (380 mg, 0.841 mmol, 3 eq.), and PdCl2(PPh3)2 (10 mg, 0.014 mmol, 0.05 eq.) were added to a three-neck flask and the mixture was purged with N2 for 15 min. Toluene (15 mL) was then added and the mixture was stirred at 120 °C overnight. 100 mL of hexane was added to the reaction solution, and the mixture was filtered to obtain a purple precipitate in a 31% yield (122 mg).

[0056] <Synthesis of [PtCl(BPIC)] (BPIC = 2,2'-((([2,2'-bipyridine]-4,4'-diylbis(3'-dodecyl-3-hexyl-[2,2'-bithiophene]-5',5-diyl))bis(methaneylylidene))bis(3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile) (PtBPIC; referred to as compound (9))> 2,2'-((([2,2'-bipyridine]-4,4'-diylbis(3'-dodecyl-3-hexyl-[2,2'-bithiophene]-5',5-diyl))bis(methaneylylidene))bis(3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile (60 mg, 0.043 mmol, 1 eq.) and PtCl2(DMSO)2 (18.1 mg, 0.043 mmol, 1 eq.) were added to a recovery flask and the atmosphere was purged with N2 for 15 minutes. THF (15 mL) was then added and the mixture was stirred at 60 °C for 24 hours. The reaction solution was concentrated using an evaporator and purified using a silica gel column containing 3 wt% NEt3 to obtain a purple precipitate in a 76% yield (54 mg). The structure of compound (9) is shown below.

[0057]

Chem.

[0058] For the obtained platinum complexes PtTIC (Compound (2)) and PtT2IC (Compound (5)), their crystal structures were clarified by single-crystal X-ray structural analysis, and their ultraviolet-visible absorption spectra were measured. Both platinum complexes showed a deep blue color in solution and strong light absorption around 600 nm, indicating that these platinum complexes have high potential as materials for solar cells.

[0059] Next, PtCDTIC (Compound 12) was synthesized. The synthesis process is shown in Figure 3. <trans-[Pt(CDT-inden)2(PBu3)2](CDT-inden=(Z)-2-(2-((6-ethynyl-4,4-dihexyl-4H-cyclopenta[2,1-b:3,4-b’]dithiophen-2-yl)methylene)-3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile) (Synthesis of PtCDTIC: Compound 12)>

[0060] <4,4-dihexyl-6-((trimethylsilyl)ethynyl)-4H-cyclopenta[2,1-b:3,4-b’]dithiophene-2-carbaldehyde (Synthesis of Compound 10)> 6-bromo-4,4-dihexyl-4H-cyclopenta[2,1-b:3,4-b’]dithiophene-2-carbaldehyde (1.04 g, 2.29 mmol, 1 eq.), CuI (22 mg, 0.115 mmol, 0.05 eq.), PdCl2(PPh3)2 (40 mg, 0.06 mmol, 0.025 eq.) were added to a round-bottom flask, and N2 was passed through for 15 minutes. Next, THF (40 mL) and NEt3 (20 mL) were added, followed by TMSA (0.38 mL, 2.75 mmol, 1.2 eq.).

[0061] The solution was protected from light and stirred at room temperature for 17 hours. H2O (60 mL) was added to this solution to quench the reaction, and hexane was used for extraction. After dehydration with MgSO4, the solution was concentrated using a rotary evaporator. Purification by silica gel chromatography gave a yellow oil with a yield of 87%. Next, deprotection was carried out with a mixture of 2 M KOH, CHCl3 and MeOH. Since the deprotected intermediate was unstable in air, it was used in the next reaction without further purification and analysis.

[0062] <Synthesis of trans-[Pt(CDTCHO)2(PBu3)2] (CDTCHO = 6-ethynyl-4,4-dihexyl-4H-cyclopenta[2,1-b:3,4-b’]dithiophene-2-carbaldehyde) (Compound 11)> 6-Ethynyl-4,4-dihexyl-4H-cyclopenta[2,1-b:3,4-b’]dithiophene-2-carbaldehyde (756 mg, 1.89 mmol, 3 eq.) deprotected with trimethylsilyl group, tans-[PtCl2(PBu3)2] (424 mg, 0.63 mmol, 1 eq.), and CuI (6 mg, 0.03 mmol, 0.05 eq.) were added to a round-bottom flask, and N2 was passed through for 15 minutes.

[0063] Thereafter, dehydrated CH2Cl2 (40 mL) and NEt3 (20 mL) were sequentially added, and the mixture was stirred at room temperature for 30 minutes. 50 mL of H2O was added to quench the reaction, and the mixture was extracted with CH2Cl2, dehydrated with MgSO4, and concentrated using an evaporator. The crude product was purified by a silica gel column containing 3 wt% NEt3 to obtain a red oil with a yield of 92%.

[0064] trans-[Pt(CDTCHO)2(PBu3)2] (Compound 11) (400 mg, 0.287 mmol, 1 eq.) and 2-(3-oxo-2,3-dihydro-1H-inden-1-ylidene) malononitrile (334 mg, 1.72 mmol, 6 eq.) were added to a two-necked flask, and N2 was passed through for 15 minutes. Thereafter, dehydrated CHCl3 (30 mL) was added to dissolve the mixture, and pyridine (0.3 mL) was added at room temperature.

[0065] The reaction mixture immediately turned dark green, and after heating at 60°C for 17 hours, it became a green solution. 30 mL of EtOH was added to the reaction mixture, and the chloroform was concentrated on a rotary evaporator and filtered to obtain a black solid. This solid was purified on a silica gel column containing 3 wt% NEt3 to obtain a dark blue solid (446 mg) in 89% yield. The structure of compound (12) is shown below.

[0066] [ka]

[0067] <Fabrication and evaluation of thin-film solar cells> After cleaning the glass substrate with the ITO film pattern, it was subjected to UV ozone treatment. Next, a zinc acetate solution in 2-methoxyethanol was spin-coated at 4000 rpm for 60 seconds and thermally annealed in air for 1 hour. The substrate with the zinc oxide film was placed in a glove box, and platinum complexes PtTIC (compound (2)) or PtT2IC (compound (5)) as acceptors and PTB7-Th, PM6, and P3HT as donors were dissolved in a chlorobenzene solution containing 0.5 wt% 1,8-diiodooctane. A photoactive layer (100 nm thick) was then formed by spin-coating.

[0068] PTB7-Th is Poly([2,6'-4,8-di(5-ethylhexylthienyl)benzo[1,2-b;3,3-b]dithiophene]{3-fluoro-2[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl}), PM6 is Poly[(2,6-(4,8-bis(5-(2-ethylhexyl)-4-fluorothiophen-2-yl)-benzo[1,2-b:4,5-b']dithiophene))-alt-(5,5-(1',3'-di-2-thienyl-5',7'-bis(2-ethylhexyl)benzo[1',2'-c:4',5'-c']dithiophene-4,8-dione))], and P3HT is Poly(3-hexylthiophene-2,5-diyl).

[0069] In addition, the non-platinum complex BPIC (compound (8)) and the platinum complex PtBPIC (compound (9)) were prepared by dissolving PTB7-Th as a donor in a chlorobenzene solution containing 1 wt% 1,8-diiodooctane, and spin-coating the solution to form a photoactive layer (film thickness 120 nm).

[0070] Next, an 8-nm-thick molybdenum trioxide (MoO3) film was deposited on the active layer as a hole extraction layer, followed by an 80-nm-thick silver film as an electrode layer using a resistance heating vacuum deposition method, producing an organic thin-film solar cell element measuring 0.035 cm square. The resulting organic thin-film solar cell was irradiated with a constant amount of light using a solar simulator (AM1.5G filter, irradiance 100 mW / cm2), and the generated current and voltage were measured.

[0071] The results for the platinum complex PtTIC (compound (2)) as the acceptor and PTB7-Th, PM6, and P3HT as the donors are shown in Figure 4. The results for the platinum complex PtT2IC (compound (5)) as the acceptor and PTB7-Th, PM6, and P3HT as the donors are shown in Figure 5. The results for the non-platinum complex BPIC (compound (8)) and the platinum complex PtBPIC (compound (9)) as the acceptor and PTB7-Th as the donor are shown in Figure 6.

[0072] In Figures 4 to 6, (a) shows the voltage-short-circuit current density characteristics, (b) shows wavelength-ICPE (incident photon to electron conversion efficiency), (c) shows the structural formula of the compound, (d) shows manufacturing specifications, and (e) shows the values ​​of various photoelectric conversion characteristics read from graphs (a) and (b). Also, (f) shows the structure of the prototype battery.

[0073] In (d), "DA ratio" indicates the ratio (weight ratio) of the donor to the acceptor, and "DIO" indicates 1,8-Diiodooctane. In Figure 4(f), the notation "donor: PtTIC" means that the material shown in Figure 4(e) was used as the donor, and PtTIC was used as the acceptor. This is also true for Figures 5 to 7.

[0074] The ITO and zinc oxide films on the SiO2 substrate, the molybdenum trioxide layer on top of the donor-acceptor (active layer), and the silver film of the electrode are the same in Figures 4 to 6. In other words, only the structure of the active layer is different.

[0075] 4 to 6, the device with PTB7-Th:PtT2IC as the active layer had the highest photoelectric conversion efficiency PCE of 2.33% (Fig. 5), but the PM6:PtT2IC device showed an extremely high open circuit voltage VOC of 1.06 V (Fig. 5).

[0076] The properties of PtCDTIC (compound 12) as an acceptor were also confirmed by fabricating a device. After cleaning a glass substrate with an ITO film pattern, it was subjected to UV ozone treatment. Next, a zinc acetate solution in 2-methoxyethanol was spin-coated at 4000 rpm for 60 seconds and thermally annealed in air for 1 hour. The substrate with the zinc oxide film was then brought into a glove box, and a photoactive layer (100 nm thick) was formed by spin-coating using a chlorobenzene solution containing PtCDTIC and PTB7-Th,PM6 in 1,8-diiodooctane at 1.0 wt%.

[0077] A photoactive layer (100 nm thick) was formed by spin coating using a chlorobenzene solution containing 0.5 wt% 1,8-diiodooctane as P3HT. Furthermore, an 8 nm thick molybdenum trioxide (MoO3) film was deposited on the active layer as a hole extraction layer, followed by an 80 nm thick silver film as an electrode layer, using a resistance heating vacuum deposition method, to produce an organic thin-film solar cell element measuring 0.035 cm square. The obtained organic thin-film solar cell was then subjected to solar simulation using a solar simulator (AM1.5G filter, irradiance 100 mW / cm). 2 The generated current and voltage were measured using a constant light source. The results are shown in Figure 7.

[0078] In Figure 7, (a) shows the voltage-short-circuit current density characteristics, (b) shows wavelength-ICPE (incident photon to electron conversion efficiency), (c) shows the structural formula of the compound, (d) shows manufacturing specifications, and (e) shows the values ​​of various photoelectric conversion characteristics read from graphs (a) and (b). (f) shows the structure of the prototype battery.

[0079] In Figure 7, the photoelectric conversion efficiency (PCE) of the device using PTB7-Th:PtCDTIC as the active layer was 3.08%, which was higher than that of PTB7-Th:PtT2IC in Figure 5. The open circuit voltage (VOC) also showed a high value of 0.94 V.

[0080] As described above, the present invention relates to n-type semiconductors (non-fullerene acceptors) for organic thin-film solar cells, and provides new platinum-containing non-fullerene acceptors. These materials are dyes that exhibit strong absorption in the visible to near-infrared region and are useful as n-type semiconductor materials for organic thin-film solar cells. [Industrial Applicability]

[0081] The platinum complex according to the present invention can be suitably used as an acceptor unit in the active layer of a thin-film solar cell, and can be suitably used in a thin-film solar cell using this active layer.

Claims

1. Platinum complexes having structures of Type 1 to Type 6 in which a donor unit D and an acceptor unit A coexist. 【Chemistry 101】 Here, R １ has the following structures R1_1 to R1_12 【Chemical Engineering 102】 Incidentally, in all types from Type 1 to Type 6, X represents hydrogen and halogen elements (H, F, Cl, Br, I), and R ２ and R ３ represents an alkyl group where n is 0 to 18. The donor unit D includes the following structures DU1 to DU41: 【Chemistry 103】 【Chemical 104】 【Chemistry 105】 【Chemistry 106】 Here, R ４ contains the following 12 structures, DR4_1 to DR4_12: 【Chemistry 107】 In addition, including DU1 to DU41, X represents hydrogen and halogen elements (H, F, Cl, Br, I), and R ５ and R ６ represents an alkyl group where n is 0 to 18. The acceptor unit A contains 43 structures from AU1 to AU43. 【Chemistry 108】 【Chemistry 109】 【Chemical 110】 【Chemistry 111】 【Chemistry 112】 In addition, in AU1 to AU43, R ７ and R ８ Contains 12 structures, AR78_1 to AR78_12 【Chemistry 113】 In addition, including AU1 to AU43, X １ , X ２ , X ３ , X ４ represents hydrogen and halogen elements (H, F, Cl, Br, I), and R ９ and R １０ represents an alkyl group where n is 0 to 18. A in AU1 to AU43 １ contains seven structures from AA1_1 to AA1_7 【Chemical 114】 In addition, in the structures of AA1_1 to AA1_7, R ７ and R ８ contains 12 structures, AA1R78_1 to AA1R78_12 【Chemical 115】 In addition, including AA1_1 to AA1_7, X １ , X ２ , X ３ , X ４ represents hydrogen and halogen elements (H, F, Cl, Br, I), and R ９ and R １０ represents an alkyl group where n is 0 to 18.

2. A thin-film solar cell having an active layer comprising an acceptor and a donor, A thin-film solar cell comprising the platinum complex according to claim 1 as an acceptor in the active layer.

3. 3. The thin-film solar cell according to claim 2, wherein the acceptor comprises any one of PtTIC, PtT2IC, PtBPIC, and PtCDTIC.

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