A small molecule co-sensitizer synergistic acid / alkali dye co-sensitized solar cell photoanode

Abstract

The application discloses a kind of small molecule co-sensitizer synergic acid / base dye co-sensitized solar cell photoanode, the photoanode is composed of FTO conductive glass substrate, titanium dioxide layer, dye sensitized layer, the titanium dioxide layer is intermediate layer, and dye sensitized layer is surface layer;The dye sensitized layer is composed of acid sensitizer, basic sensitizer, small molecule co-sensitizer compound composition.The acid / base dye co-sensitizer on the photoanode of the application has the characteristics of no competitive adsorption, while having complementary ultraviolet-visible absorption spectrum, and the addition of small molecule co-sensitizer can fill the gap of acid / base dye co-sensitizer, increase the dye load of photoanode, while inhibiting interface charge recombination and dye aggregation.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of dye-sensitized solar cells, and particularly relates to a solar cell photoanode with small-molecule co-sensitizer and acid / alkali dye co-sensitization. BACKGROUND

[0002] In recent years, environmental pollution and shortage of fossil fuels have stimulated the rapid growth of new energy. Photovoltaic technology provides a feasible method for solar energy, a new energy. Dye-sensitized solar cells are one of the third generation solar cells, and have the manufacturing characteristics of double-sided light trapping, multi-color transparency, flexible adjustment, low cost, high theoretical efficiency, etc. However, the energy conversion efficiency and long-term stability need to be further improved to ensure the successful commercial application of dye-sensitized solar cells in the future. Photosensitizers, also known as “photonic motors”, are the engine of dye-sensitized solar cells, aiming to obtain a wider absorption spectrum and high energy conversion efficiency. However, the current bottlenecks of dye-sensitized solar cells include aggregation caused by single dye sensitization, narrow light spectrum absorption range, long-term stability and low energy conversion efficiency. However, co-sensitization is an effective strategy to improve the performance of the device, which is to co-sensitize the working electrode of the dye-sensitized solar cell by two or more dye sensitizers with complementary absorption spectrum. SUMMARY

[0003] The technical problem to be solved by the present application is to provide a solar cell photoanode with small-molecule co-sensitizer and acid / alkali dye co-sensitization, which fills the gap of the acid / alkali dye co-sensitization system by using small-size co-sensitizer to improve the performance of the solar cell photoanode.

[0004] The solar cell photoanode with small-molecule co-sensitizer and acid / alkali dye co-sensitization solves the above technical problems, and the photoanode is composed of FTO conductive glass, a titanium dioxide layer and a dye-sensitized layer. The titanium dioxide layer is an intermediate layer, and the dye-sensitized layer is a surface layer. The dye-sensitized layer is composed of an acid sensitizer, an alkali sensitizer and a small-molecule co-sensitizer. The molar ratio of the acid sensitizer to the alkali sensitizer is 2:3-3:2, and the molar amount of the small-molecule co-sensitizer is 20%-100% of the total molar amount of the acid sensitizer and the alkali sensitizer.

[0005] The structural formula of the acid sensitizer is as follows:

[0006]

[0007] The structural formula of the alkali sensitizer is as follows:

[0008]

[0009] The structural formula of the small-molecule co-sensitizer is as follows:

[0010]

[0011] m, n, y in the above structural formula are independently an integer from 0 to 5; preferably, m, n, y are all 1.

[0012] Further preferably, the molar ratio of the acid sensitizer to the base sensitizer in the dye-sensitized layer is 3:2, and the molar amount of the small-molecule co-sensitizer is 60% or 100% of the total molar amount of the acid sensitizer and the base sensitizer.

[0013] The synthesis route and specific preparation method of the acid sensitizer (I) and the base sensitizer (II) are as follows:

[0014]

[0015] 1. Preparation of compound c

[0016] Compound a, compound b, tetrabutylammonium bromide, dichlorobis (di-tert-butyl- (4-dimethylaminophenyl) phosphine) palladium (II), potassium carbonate are added into a mixture of N, N-dimethylformamide and distilled water in a molar ratio of 1:1.2:2.5:0.02:3, and reacted at 75°C for 8 hours. After the reaction is completed, the reaction solution is cooled to room temperature, then poured into dichloromethane, washed with water until neutral, separated organic phase, concentrated under reduced pressure, and purified to obtain compound c.

[0017] 2. Preparation of acid sensitizer (I) and base sensitizer (II)

[0018] Compound c, cyanoacetic acid and ammonium acetate are added into glacial acetic acid in a molar ratio of 1:3:3, and refluxed for 9 hours. After the reaction is completed, the reaction solution is slowly added to deionized water, and a solid is precipitated. The crude product is obtained by suction filtration, and purified by column chromatography to obtain the acid sensitizer (I).

[0019] Under the condition of nitrogen protection, compound c and 4-methylpyridine are added into acetic anhydride in a molar ratio of 1:2, and reacted at 140°C for 24 hours. After the reaction is completed, the reaction solution is poured into saturated potassium hydroxide aqueous solution, dichloromethane is added, stirred, the organic phase is separated, concentrated under reduced pressure, and purified to obtain the base sensitizer (II).

[0020] The synthesis route and specific preparation method of the small-molecule co-sensitizer (III) are as follows:

[0021]

[0022] 1. Preparation of compound f

[0023] Compound d, compound e, dichlorobis(di-tert-butyl-(4-dimethylamino phenyl) phosphine) palladium (II), potassium acetate are added into dioxane in a molar ratio of 1:1.5:0.05:5, and constant temperature reaction is carried out at 90 DEG C for 8 hours; after the reaction is completed, the reaction liquid is reduced to room temperature, then poured into dichloromethane, washed with water until neutral, the organic phase is separated, concentrated under reduced pressure, and purified to obtain compound f.

[0024] 2, Preparation of compound h

[0025] Compound f, compound g, tetrabutylammonium bromide, dichlorobis(di-tert-butyl-(4-dimethylamino phenyl) phosphine) palladium (II), potassium carbonate are added into a mixture of N, N-dimethylformamide and distilled water in a molar ratio of 1:1.1:2.5:0.02:3, and reaction is carried out at 75 DEG C for 4 hours; after the reaction is completed, the reaction liquid is reduced to room temperature, then poured into dichloromethane, washed with water until neutral, the organic phase is separated, concentrated under reduced pressure, and purified to obtain compound h.

[0026] 3, Preparation of small molecule co-sensitizer (III)

[0027] Compound h, cyanoacetic acid and ammonium acetate are added into glacial acetic acid in a molar ratio of 1:3:3, and reflux reaction is carried out for 5 hours; after the reaction is completed, the reaction liquid is slowly added into deionized water, and solid is precipitated; then dichloromethane is added, washed with water until neutral, the organic phase is separated, concentrated under reduced pressure, and purified to obtain small molecule co-sensitizer (III).

[0028] The preparation method of the solar cell photoanode of the application comprises the following steps:

[0029] Step one: acid sensitizer, base sensitizer and small molecule co-sensitizer are respectively added into a mixed solution of t-butyl alcohol and acetonitrile in a volume ratio of 1:1, and ultrasonic dispersion is carried out to obtain 0.4 mmol / L acid sensitizer solution, base sensitizer solution and small molecule co-sensitizer solution respectively;

[0030] Step two: the acid sensitizer solution, base sensitizer solution and small molecule co-sensitizer solution of step one are mixed to obtain a dye bath; the molar ratio of the acid sensitizer to the base sensitizer in the dye bath is 2:3-3:2, and the molar amount of the small molecule co-sensitizer is 20%-100% of the total molar amount of the acid sensitizer and the base sensitizer;

[0031] Step three: under light-proof conditions, the titanium dioxide loaded FTO conductive glass is immersed in the dye bath for 24 hours, then taken out, washed with dichloromethane and dried to obtain the solar cell photoanode.

[0032] In step two, the molar ratio of the acid sensitizer to the base sensitizer in the dye bath is preferably 3:2, and the molar amount of the small molecule co-sensitizer is 60% or 100% of the total molar amount of the acid sensitizer and the base sensitizer.

[0033] The beneficial effects of the present application are as follows:

[0034] The acid / base dyes on the photoanode of the present application have the feature of non-competitive adsorption, and the ultraviolet-visible absorption spectrum of the photoanode has a complementary effect when the acid / base dyes are co-sensitized. At the same time, the addition of small molecule co-sensitizer can fill the gap of the acid / base dyes, which is conducive to the increase of the dye loading capacity on the photoanode, reduces the interface charge recombination and dye aggregation, and makes the obtained photoanode have higher photoelectron density, thereby improving the energy conversion efficiency of the whole device. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 is the ultraviolet-visible absorption spectrum of the acid sensitizer (I-1), the base sensitizer (II-1) and the small molecule sensitizer (III-1) prepared in Example 1 in dichloromethane solution.

[0036] Figure 2 is the ultraviolet-visible absorption spectrum of the acid sensitizer (I-1), the base sensitizer (II-1), the small molecule sensitizer (III-1) respectively sensitized, the acid dye sensitizer (I-1) and the base dye sensitizer (II-1) co-sensitized, and the acid dye sensitizer (I-1), the base dye sensitizer (II-1) and the small molecule dye sensitizer (III-1) ternary co-sensitized on the titanium dioxide film. DETAILED DESCRIPTION

[0037] The present application will be further described in detail below in combination with the drawings and examples, but the protection scope of the present application is not limited to these examples.

[0038] The acid sensitizer (I-1) is synthesized, and the specific synthesis route and method are as follows:

[0039]

[0040] 1. Preparation of compound c-1

[0041] Into a 150 mL three-necked flask with a thermometer, 0.70 g (1.52 mmol) of compound a-1, 0.50 g (1.82 mmol) of compound b, 1.22 g (3.79 mmol) of tetrabutylammonium bromide were added in turn, then 20 mL of N,N-dimethylformamide, 21.48 mg (0.30 mmol) of dichlorobis(di-tert-butyl-(4-dimethylaminophenyl)phosphine)palladium(II) were added, after stirring uniformly, 6 mL (4.55 mmol) of potassium carbonate aqueous solution was slowly dropped, and the reaction was carried out at 75°C for 6 hours. After the reaction was completed, the reaction liquid was reduced to room temperature, then poured into dichloromethane, washed with water until neutral, the organic phase was separated, and concentrated under reduced pressure to obtain a crude product. After purification by column chromatography (developing agent: a mixture of dichloromethane and petroleum ether in a volume ratio of 1:1, filler: 200-300 mesh silica gel), 0.76 g of compound c-1 was obtained, with a yield of 82.00%.

[0042] 2. Preparation of acidic sensitizer (I-1)

[0043] Into a 150 mL three-necked flask with a thermometer, 0.73 g (1.20 mmol) of compound c-1, 0.30 g (3.59 mmol) of cyanoacetic acid and 0.28 g (3.59 mmol) of ammonium acetate were added in turn, then 30 mL of glacial acetic acid was added, and the reaction was carried out under reflux for 9 hours. After the reaction was completed, the reaction liquid was slowly dropped into a beaker containing 150 mL of deionized water, and a magnetic stirrer was started to slowly stir. Purple solid was precipitated, and a crude product was obtained by suction filtration. After purification by column chromatography (developing agent: a mixture of ethyl acetate and petroleum ether in a volume ratio of 2:5, filler: 200-300 mesh silica gel), 0.46 g of acidic sensitizer (I-1) was obtained, with a yield of 58.23%.

[0044] The nuclear magnetic resonance data of the prepared acidic sensitizer (I-1) are as follows: 1 H NMR (600 MHz, DMSO-d6) δ 8.46 (s, 1H), 7.95 (d, J = 4.1 Hz, 1H), 7.60-7.45 (m, H), 7.38 (d, J = 3.9 Hz, 1H), 7.03 (d, J = 8.8 Hz, 4H), 6.91 (d, J = 8.9 Hz, 4H), 6.73 (d, J = 8.7 Hz, 2H), 3.95 (t, J = 6.6 Hz, 4H), 1.77 (dp, J = 13.4, 6.7 Hz, 2H), 1.60 (q, J = 6.7 Hz, 4H), 0.93 (d, J = 6.7 Hz, 12H).

[0045] Synthesis of basic sensitizer (II-1), and the specific synthesis route and method are as follows:

[0046]

[0047] Into a 25 mL sealed tube with a magnetic bar, 0.50 g (0.82 mmol) of compound c-1, 0.15 g (1.64 mmol) of 4-methylpyridine, 7 mL of acetic anhydride were sequentially added under nitrogen protection, vacuumized, and reacted at 140 °C for 24 hours. The reaction liquid was first poured into 100 mL of ice water, then 200 mL of saturated potassium hydroxide aqueous solution was added, 50 mL of dichloromethane was added, and the organic phase was separated after stirring for 30 min, concentrated under reduced pressure, and purified by column chromatography (eluent: methanol and dichloromethane in a volume ratio of 1:15, filler: 200-300 mesh silica gel) to obtain 0.08 g of basic sensitizer (II-1), with a yield of 14.23%.

[0048] The nuclear magnetic resonance data of the prepared basic sensitizer (II-1) are as follows: 1 H NMR (600 MHz, CDCl3) δ 8.47 (s, 2H), 7.31-7.25 (m, 3H), 7.21 (d, J = 5.2 Hz, 2H), 7.05 (d, J = 3.8 Hz, 1H), 7.016.97 (m, 6H), 6.95 (d, J = 3.8 Hz, 1H), 6.83 (d, J = 8.7 Hz, 2H), 6.75 (d, J = 8.9 Hz, 4H), 6.66 (d, J = 16.0 Hz, 1H), 3.88 (t, J = 6.6 Hz, 4H), 1.76 (dt, J = 13.4, 6.7 Hz, 2H), 1.60 (q, J = 6.7 Hz, 4H), 0.89 (d, J = 6.7 Hz, 12H).

[0049] The small molecule co-sensitizer (III-1) was synthesized, and the specific synthesis route and method are as follows:

[0050]

[0051] 1. Preparation of compound f-1

[0052] Into a 150 mL three-necked flask with a thermometer, 3.50 g (13.79 mmol) of compound e, 20 mL of dioxane were added successively, after compound e was dissolved completely, 2.00 g (6.89 mmol) of d-1, 5.41 g (55.14 mmol) of potassium acetate and 0.25 mg (0.34 mmol) of dichlorobis (di-tert-butyl- (4-dimethylaminophenyl) phosphine) palladium (II) were added, then 10 mL of dioxane was added, the reaction system was reacted at 90°C for 8 hours, after the reaction was completed, the reaction liquid was cooled to room temperature, then poured into dichloromethane, washed with water until neutral, the organic phase was separated, concentrated under reduced pressure, to obtain the crude product, after purification by column chromatography (eluent: dichloromethane and petroleum ether in a volume ratio of 4:1, packing material: 200-300 mesh silica gel), 0.50 g of compound f-1 was obtained, with a yield of 25.00%.

[0053] 4, Preparation of compound h-1

[0054] Into a 150 mL three-necked flask with a thermometer, 0.50 g (2.01 mmol) of compound g, 0.64 g (2.21 mmol) of compound f-1, 1.62 g (6.02 mmol) of tetrabutylammonium bromide and 28.43 mg (0.40 mmol) of dichlorobis (di-tert-butyl- (4-dimethylaminophenyl) phosphine) palladium (II) were added successively, after the reaction liquid was stirred uniformly, 5 mL (6.02 mmol) of potassium carbonate aqueous solution was slowly added dropwise, the reaction system was reacted at 75°C for 4 hours, after the reaction was completed, the reaction liquid was cooled to room temperature, then poured into dichloromethane, washed with water until neutral, the organic phase was separated, concentrated under reduced pressure, to obtain the crude product, after purification by column chromatography (eluent: dichloromethane and petroleum ether in a volume ratio of 1:2, packing material: 200-300 mesh silica gel), 0.47 g of compound h-1 was obtained, with a yield of 71.00%.

[0055] 5, Preparation of small molecule co-sensitizer (III-1)

[0056] Into a 150 mL three-necked flask with a thermometer, 0.40 g (1.20 mmol) of compound h-1, 0.30 g (3.61 mmol) of cyanoacetic acid and 0.28 g (3.61 mmol) of ammonium acetate, 25 mL of glacial acetic acid were added successively, refluxed for 5 hours, after the reaction was completed, the reaction liquid was slowly added to deionized water, a solid was precipitated, then dichloromethane was added, washed with water until neutral, the organic phase was separated, concentrated under reduced pressure, to obtain the crude product, after purification by column chromatography (eluent: dichloromethane and petroleum ether in a volume ratio of 1:2, packing material: 200-300 mesh silica gel), 0.22 g of small molecule co-sensitizer (III-1) was obtained, with a yield of 45.83%.

[0057] The nuclear magnetic data of the prepared small molecule co-sensitizer (III-1) are as follows: 1 H NMR (600 MHz, DMSO-d6) δ 8.08 (s, 1H), 7.66 (d, J = 8.8 Hz, 2H), 7.02 (d, J = 8.9 Hz, 2H), 4.41 (dd, J = 21.3, 4.4 Hz, 4H), 4.03 (t, J = 6.6 Hz, 2H), 1.83 - 1.73 (m, 1H), 1.64 - 1.56 (m, 2H), 0.94 (d, J = 6.7 Hz, 6H).

[0058] The acid sensitizer (I-1), the basic sensitizer (II-1) and the small molecule co-sensitizer (III-1) were respectively dissolved in dichloromethane to prepare a solution with a concentration of 1×10 -5 mol / L. The UV-Vis absorption spectrum of the solution was tested by using a UV-Vis spectrophotometer (model UV-2250, produced by Shimadzu Corporation, Japan), and the result is shown in Figure 1 . The test result shows that the maximum absorption wavelengths are 494 nm, 439 nm and 412 nm respectively, and the molar absorption coefficients are 57803 M -1 cm -1 , 52985 M -1 cm -1 and 49400 M -1 cm -1 .

[0059] The three-dimensional spatial configuration and the molecular size of the acid sensitizer (I-1), the basic sensitizer (II-1) and the small molecule co-sensitizer (III-1) were obtained by using the density functional theory calculation through the Gaussian 03 software (RB3LYP / 6-311G(d, p) level), which are and respectively. It is indicated that the small molecule co-sensitizer has excellent molecular matching structure with the acid / basic dye co-sensitization system.

[0060] Example 1

[0061] Preparation of a solar cell photoanode

[0062] Step one: the acid sensitizer (I-1), the basic sensitizer (II-1) and the small molecule co-sensitizer (III-1) were respectively added into a mixed solution of t-butyl alcohol and acetonitrile with a volume ratio of 1:1, and were uniformly dispersed by ultrasonic treatment to obtain an acid sensitizer solution, a basic sensitizer solution and a small molecule co-sensitizer solution with a concentration of 0.4 mmol / L respectively;

[0063] Step two: mix the acid sensitizer solution, the basic sensitizer solution and the small molecule co-sensitizer solution of step one to obtain a dye bath; the molar ratio of the acid sensitizer to the basic sensitizer in the dye bath is 3:2, and the molar amount of the small molecule co-sensitizer is 100% of the total molar amount of the acid sensitizer and the basic sensitizer respectively;

[0064] Step three: immerse the FTO conductive glass loaded with titanium dioxide in the dye bath under light-proof conditions for 24 hours, then take it out, rinse it with dichloromethane, and dry it to obtain a solar cell light anode.

[0065] An ultraviolet-visible spectrophotometer is used to test the ultraviolet-visible absorption spectrum of the solar cell light anode. The acid sensitizer (I-1), the basic sensitizer (II-1) and the small molecule co-sensitizer (III-1) are respectively used to individually sensitize the light anode, and the acid sensitizer (I-1) and the basic sensitizer (II-1) are mixed in a molar ratio of 3:2 to co-sensitize the light anode. The test results are shown in Figure 2 . The test results show that the acid sensitizer (I-1) and the basic sensitizer (II-1) co-sensitized in the ultraviolet-visible absorption spectrum achieve good absorption complementary effect, and the molar extinction coefficient is greatly improved after adding the small molecule co-sensitizer (III-1).

[0066] Example 2

[0067] In step two of this example, the molar ratio of the acid sensitizer to the basic sensitizer in the dye bath is 3:2, and the molar amount of the small molecule co-sensitizer is 20% of the total molar amount of the acid sensitizer and the basic sensitizer respectively. The other steps are the same as those in Example 1 to obtain a solar cell light anode.

[0068] Example 3

[0069] In step two of this example, the molar ratio of the acid sensitizer to the basic sensitizer in the dye bath is 3:2, and the molar amount of the small molecule co-sensitizer is 40% of the total molar amount of the acid sensitizer and the basic sensitizer respectively. The other steps are the same as those in Example 1 to obtain a solar cell light anode.

[0070] Example 4

[0071] In step two of this example, the molar ratio of the acid sensitizer to the basic sensitizer in the dye bath is 3:2, and the molar amount of the small molecule co-sensitizer is 60% of the total molar amount of the acid sensitizer and the basic sensitizer respectively. The other steps are the same as those in Example 1 to obtain a solar cell light anode.

[0072] Example 5

[0073] In step two of the present example, the molar ratio of the acid sensitizer to the base sensitizer in the dye bath is 3:2, and the molar amount of the small-molecule co-sensitizer is 80% of the total molar amount of the acid sensitizer and the base sensitizer. The other steps are the same as those in Example 1, and a solar cell photoanode is obtained.

[0074] Example 6

[0075] In step two of the present example, the molar ratio of the acid sensitizer to the base sensitizer in the dye bath is 2:3, and the molar amount of the small-molecule co-sensitizer is 100% of the total molar amount of the acid sensitizer and the base sensitizer. The other steps are the same as those in Example 1, and a solar cell photoanode is obtained.

[0076] Example 7

[0077] In step two of the present example, the molar ratio of the acid sensitizer to the base sensitizer in the dye bath is 1:1, and the molar amount of the small-molecule co-sensitizer is 100% of the total molar amount of the acid sensitizer and the base sensitizer. The other steps are the same as those in Example 1, and a solar cell photoanode is obtained.

[0078] The photoanodes obtained in Examples 1-5 above are respectively prepared into dye-sensitized solar cells, and the dye-sensitized solar cells are tested by using a J-V characteristic test system (QTest Hifinity 5 Solar Cell IPCE Test System). Meanwhile, dye-sensitized solar cells prepared by using photoanodes sensitized by the acid sensitizer (I-1), the base sensitizer (II-1), and the small-molecule co-sensitizer (III-1) respectively, and a photoanode sensitized by mixing the acid sensitizer (I-1) and the base sensitizer (II-1) in a molar ratio of 3:2 are tested for comparison, and the results are shown in Table 1.

[0079] Table 1: Test results of solar cell performance

[0080]

[0081]

[0082] As shown in Table 1, compared with the base sensitizer (II-1), the photoelectric conversion efficiency of the solar cell prepared by using the photoanode sensitized by the acid sensitizer (I-1) and the base sensitizer (II-1) in a molar ratio of 3:2 is increased by 57.05%. Compared with the small-molecule co-sensitizer (III-1), the photoelectric conversion efficiency of the solar cell prepared by using the ternary co-sensitizer is increased from 2.63% to 6.40%.

Claims

1. A solar cell photoanode co-sensitized by a small molecule co-sensitizer and an acid / base dye, wherein the photoanode comprises FTO conductive glass, a titanium dioxide layer, and a dye-sensitized layer, wherein the titanium dioxide layer is an intermediate layer and the dye-sensitized layer is a surface layer; characterized in that, The dye-sensitized layer is composed of an acid sensitizer, a base sensitizer and a small molecule co-sensitizer. The acid sensitizer has the following structural formula: The base sensitizer has the following structural formula: The small molecule co-sensitizer has the following structural formula: In the structural formula, m, n and y are independently 0-5. In the dye-sensitized layer, the molar ratio of the acid sensitizer to the base sensitizer is 2:3-3:2, and the molar amount of the small molecule co-sensitizer is 20%-100% of the total molar amount of the acid sensitizer and the base sensitizer.

2. The solar cell photoanode sensitized by small molecule co-sensitizer in cooperation with acid / base dye co-sensitizer according to claim 1, characterized in that, In the dye-sensitized layer, the molar ratio of the acid sensitizer to the base sensitizer is 3:2, and the molar amount of the small molecule co-sensitizer is 60% or 100% of the total molar amount of the acid sensitizer and the base sensitizer.

3. The solar cell photoanode sensitized by small molecule co-sensitizer in cooperation with acid / base dye co-sensitizer according to claim 1, characterized in that, The values of m, n and y are all 1.

4. The solar cell photoanode sensitized by small molecule co-sensitizer in cooperation with acid / base dye co-sensitizer according to claim 1, characterized in that, The preparation method of the photoanode is as follows: Step one: the acid sensitizer, the base sensitizer and the small molecule co-sensitizer are respectively added into a mixed solution of t-butyl alcohol and acetonitrile with a volume ratio of 1:1, and are uniformly dispersed by ultrasonic, to obtain 0.4 mmol / L acid sensitizer solution, base sensitizer solution and small molecule co-sensitizer solution respectively; Step two: the acid sensitizer solution, the base sensitizer solution and the small molecule co-sensitizer solution in step one are mixed to obtain a dye bath; in the dye bath, the molar ratio of the acid sensitizer to the base sensitizer is 2:3-3:2, and the molar amount of the small molecule co-sensitizer is 20%-100% of the total molar amount of the acid sensitizer and the base sensitizer; Step three: under the condition of avoiding light, the FTO conductive glass loaded with titanium dioxide is immersed in the dye bath for 24 hours, is then taken out, washed with dichloromethane, dried, and a solar cell photoanode is obtained.

5. The solar cell photoanode sensitized by small molecule co-sensitizer in cooperation with acid / base dye co-sensitizer according to claim 4, characterized in that, In step two, in the dye bath, the molar ratio of the acid sensitizer to the base sensitizer is 3:2, and the molar amount of the small molecule co-sensitizer is 60% or 100% of the total molar amount of the acid sensitizer and the base sensitizer.

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