Tin-based perovskite precursor solution and preparation method and application thereof

Abstract

The invention belongs to the technical field of tin-based perovskite batteries, and particularly discloses a tin-based perovskite precursor solution and a preparation method and application thereof. According to the invention, 2-benzyl-2-isothiourea hydrochloride is added into a tin-based perovskite precursor solution, amino (-NH2) and thioether (C-S-C) contained in the 2-benzyl-2-isothiourea hydrochloride play a role of Lewis base and can be combined with Sn < 2 + > with insufficient coordination to inhibit oxidation of Sn < 2 + > to Sn < 4 + >, so that the crystallization rate of perovskite is reduced, and the growth defect of a passivation film is overcome; the charge transport performance of the tin-based perovskite light absorption layer is improved, the photoelectric conversion efficiency is improved, and good stability is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of novel thin-film solar cells, and in particular relates to a tin-based perovskite precursor solution and a preparation method and application thereof. Background Art

[0002] In the field of photovoltaic technology, perovskite solar cells have broad application prospects. Among them, tin-based perovskite solar cells are developing rapidly because of their advantages such as low toxicity, near-ideal band gap, high carrier mobility, long carrier diffusion distance, and strong light absorption. However, the extranuclear electronic structure of tin atoms determines its easy oxidation characteristics, which makes the tin-based perovskite light-absorbing layer susceptible to erosion by water and oxygen environment and oxidative decomposition. In addition, the crystallization rate of tin-based perovskites is too fast and difficult to control, resulting in unstable film quality, which is manifested as small film grain size, high defect density, and a large number of pinholes. Under the combined effect of these factors, the photoelectric conversion efficiency of tin-based perovskite solar cells has always been difficult to improve, and the device stability is also poor. Therefore, in order to fill the gap in the market, a large number of studies have been devoted to improving the efficiency and stability of tin-based perovskite solar cell devices.

[0003] Sufficient research has shown that the use of appropriate additives can effectively inhibit Sn 2+ Oxidation slows down the crystallization rate and obtains a dense, pinhole-free, large-grained tin-based perovskite film. Most existing studies adopt the interface modification layer scheme, that is, inserting a modified functional layer (such as CN 114284440A) between the perovskite light-absorbing layer and the charge transport layer to passivate defects, isolate water and oxygen, or promote charge transport. However, the newly added modification layer may have an adverse effect on the perovskite light-absorbing layer, and will also make the energy level matching conditions between the functional layers of the battery more complex and demanding, resulting in a weakening effect on the battery performance that is greater than the promotion effect. Summary of the invention

[0004] The object of the present invention is to provide a tin-based perovskite solar cell and a preparation method thereof. The light-absorbing layer of the tin-based perovskite solar cell contains 2-benzyl-2-isothiourea hydrochloride. The light-absorbing layer after adding 2-benzyl-2-isothiourea hydrochloride has a dense and smooth surface morphology, a low defect density, and a small number of pinholes, which is conducive to carrier transmission and has a significant improvement in photoelectric conversion efficiency and stability.

[0005] The invention provides a tin-based perovskite precursor solution containing 2-benzyl-2-isothiourea hydrochloride.

[0006] In an embodiment of the present invention, 2-benzyl-2-isothiourea hydrochloride, methylamine bromide, formamidine iodine, stannous iodide, stannous fluoride, phenethylammonium iodide, and tin powder are uniformly dissolved in an organic solvent under a protective atmosphere, and stirred at 25 to 30° C. for 8 to 10 hours to obtain a tin-based perovskite precursor solution.

[0007] Preferably, the protective atmosphere is nitrogen.

[0008] Preferably, the molar ratio of methylamine bromide, formamidine iodine, stannous iodide, stannous fluoride, phenethylammonium iodide, and tin powder is 0.25:0.75:1:0.1:0.135:0.04-0.05.

[0009] Preferably, the concentration of stannous iodide in the tin-based perovskite precursor solution is 0.9M.

[0010] Preferably, the mass concentration of the 2-benzyl-2-isothiourea hydrochloride in the tin-based perovskite precursor solution is 0.2 to 1.3 mg / mL.

[0011] Preferably, the organic solvent selected is N,N-dimethylformamide and dimethyl sulfoxide in a volume ratio of 3:1 to 4:1.

[0012] The present invention provides a method for preparing a light absorbing layer from the above-mentioned tin-based perovskite precursor solution containing 2-benzyl-2-isothiourea hydrochloride, wherein the above-mentioned tin-based perovskite precursor solution is coated on a hole transport layer under a protective atmosphere, a multi-step spin coating method is adopted and an anti-solvent is added dropwise at an appropriate time, and then a two-step annealing treatment is performed to complete the preparation of the tin-based perovskite light absorbing layer.

[0013] Preferably, the protective atmosphere is nitrogen.

[0014] Preferably, the multi-step spin coating method parameters are set to first rotate at 1000 rpm for 8 to 10 seconds, and then rotate at 6000 to 8000 rpm for 35 to 50 seconds; the annealing treatment is set to first anneal at 40 to 45° C. for 3 to 5 minutes, and then anneal at 80 to 85° C. for 10 to 20 minutes.

[0015] Preferably, the volume ratio of the precursor solution to the anti-solvent is 1:3 to 1:4.

[0016] Preferably, the anti-solvent is added dropwise for 10 to 16 seconds during the second spin coating step.

[0017] Preferably, the anti-solvent is chlorobenzene or toluene.

[0018] Preferably, the thickness of the tin-based perovskite thin film light-absorbing layer is 200-400 nm.

[0019] The present invention also provides a method for preparing a tin-based perovskite solar cell comprising the above-mentioned light absorbing layer, and the specific steps are as follows:

[0020] (1) ultrasonically dispersing the filtered hole transport layer material at a temperature of 5 to 10° C. for 20 to 40 minutes, then coating the material on a transparent conductive substrate by spin coating and annealing to form a hole transport layer;

[0021] (2) preparing a light absorbing layer on the hole transport layer according to the method for preparing a light absorbing layer from a tin-based perovskite precursor solution containing 2-benzyl-2-isothiourea hydrochloride;

[0022] (3) placing the fully dissolved and filtered electron transport layer material solution on a hot plate at 30 to 40° C., standing for 20 to 30 minutes until the solution temperature stabilizes, and then coating the solution on the tin-based perovskite light absorbing layer by spin coating and annealing to form an electron transport layer;

[0023] (4) placing a fully dissolved and filtered isopropanol saturated solution of 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) at 20-25° C. for 20-30 min, and coating the solution on the electron transport layer by spin coating and annealing to form a hole blocking layer after the solution temperature stabilizes;

[0024] (5) After the hole blocking layer is prepared, it is allowed to stand for 1 to 2 hours, and then a metal electrode layer with a thickness of 100 to 200 nm is deposited on the hole blocking layer using a vacuum coating device.

[0025] The beneficial effects of the present invention are:

[0026] The tin-based perovskite film of the present invention introduces 2-benzyl-2-isothiourea hydrochloride as a light-absorbing layer additive, which has the following five effects: First, amino group (-NH2) and sulfide (CSC) are used to act as Lewis bases to react with Sn with insufficient coordination in the tin-based perovskite. 2+ Binding, inhibiting Sn 2+ To Sn 4+ Oxidation; Second, using Cl - Doping with Sn forms a Sn-Cl bond with stronger binding energy, which is conducive to the formation of a denser lattice; third, it effectively reduces the defect density and alleviates the energy loss caused by carrier recombination; fourth, it can adjust the work function of the tin-based perovskite light-absorbing layer, which is beneficial to charge extraction and transport; fifth, it uses the hydrogen bonding between N atoms and excess metal cations to regulate the crystallization rate of the crystal.

[0027] The performance of the tin-based perovskite solar cell prepared by the present invention is significantly improved, especially in terms of photoelectric conversion efficiency and stability. Compared with the tin-based perovskite solar cell without using additives, its maximum photoelectric conversion efficiency increases from 8.55% to 9.56%, an increase of about 11.8%. After the prepared unpackaged tin-based perovskite solar cell device is placed under nitrogen conditions for 1500 hours, it still maintains an initial photoelectric conversion efficiency of more than 93.0%. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is the current density-voltage (JV) curve of the tin-based perovskite solar cell in Example 1;

[0029] Figure 2 is the current density-voltage (JV) curve of the tin-based perovskite solar cell in Example 2;

[0030] Figure 3 is the current density-voltage (JV) curve of the tin-based perovskite solar cell in Example 3;

[0031] Figure 4 is the current density-voltage (JV) curve of the tin-based perovskite solar cell in Example 4;

[0032] Figure 5 is the current density-voltage (JV) curve of the tin-based perovskite solar cell in Comparative Example 1;

[0033] Figure 6 This is the efficiency change curve of the tin-based perovskite solar cell in comparative example 1 and example 2 stored under nitrogen conditions for 1500 hours;

[0034] Figure 7 is the ultraviolet-visible (UV-Vis) absorption spectra of the tin-based perovskite films in Comparative Example 1 and Example 2;

[0035] Figure 8 is an X-ray photoelectron spectroscopy (XPS) graph of the tin-based perovskite film in Comparative Example 1 and Example 2;

[0036] Fig. 9 The results of the space charge limited current (SCLC) test of the dual electron structure device prepared based on the perovskite film in Comparative Example 1 and Example 2;

[0037] Fig.10 is the current density-voltage curve of the tin-based perovskite solar cell in the comparative example 1 and the example 2 in the dark state;

[0038] Fig.11 The open circuit voltage-light intensity (V OC-I) Dependence fitting results. DETAILED DESCRIPTION

[0039] Example 1

[0040] Step 1): ultrasonically clean the indium tin oxide transparent conductive glass with glass cleaning agent, deionized water, acetone, isopropyl alcohol and alcohol for 20 minutes each, and then put the cleaned indium tin oxide transparent conductive glass into a 60° C. oven for drying for more than 24 hours for use.

[0041] Step 2): Under a nitrogen atmosphere, methylamine bromide, formamidine iodine, stannous iodide, stannous fluoride, phenethyl ammonium iodide, tin powder, and 2-benzyl-2-isothiourea hydrochloride are mixed and dissolved in a N,N-dimethylformamide and dimethyl sulfoxide solvent with a volume ratio of 4:1, and stirred at 25°C for 8 hours, wherein the molar ratio of methylamine bromide, formamidine iodine, stannous iodide, stannous fluoride, phenethyl ammonium iodide, and tin powder is 0.25:0.75:1:0.1:0.135:0.04, the concentration of stannous iodide is 0.9M, and the concentration of 2-benzyl-2-isothiourea hydrochloride is 0.2mg / mL, to obtain a tin-based perovskite precursor solution.

[0042] 2-Benzyl-2-isothiourea hydrochloride is an additive (manufacturer: Aladdin, item number: B105227), the structural formula is:

[0043] Step 3): Take out the indium tin oxide transparent conductive glass in the oven and treat it with ultraviolet ozone for 20 minutes for use.

[0044] Step 4): The hole transport layer material PEDOT:PSS was filtered with a filter element with a pore size of 0.45 μm, ultrasonicated at 5°C for 20 min, and then 70 μL of the filtered PEDOT:PSS was pipetted and dripped on the treated indium tin oxide transparent conductive glass (area: 16×25, unit: mm2). The spin coating speed was set to first rotate at 1000 rpm for 8 s, then rotate at 5000 rpm for 30 s. After the spin coating was completed, it was immediately transferred to a hot stage at 150°C and annealed for 20 min to complete the preparation of the hole transport layer.

[0045] Step 5): The transparent conductive glass substrate with a hole transport layer prepared in step 4) is transferred to a glove box filled with nitrogen, and the tin-based perovskite precursor solution prepared in step 2) is filtered with a filter element with a pore size of 0.45 μm. 40 μL of the tin-based perovskite precursor solution is aspirated with a pipette and dripped on the hole transport layer. The spin coating speed is set to rotate at 1000 rpm for 8 seconds, then at 6000 rpm for 50 seconds. In the second step of spin coating, 130 μL of chlorobenzene is added as an anti-solvent at 12 seconds. After the spin coating is completed, it is first transferred to a hot stage at 40°C for annealing for 5 minutes, and then transferred to a hot stage at 80°C for annealing for 10 minutes to complete the preparation of the tin-based perovskite light absorbing layer.

[0046] Step 6): Spin coat 40 μL of [6,6]-phenyl C61 butyric acid methyl ester (PC) on the tin-based perovskite light-absorbing layer prepared in step 5). 61 BM) in chlorobenzene solution, wherein PC 61 The concentration of BM in chlorobenzene was 20 mg / mL. It was placed on a 30°C hot stage for 20 min before spin coating. The spin coating speed was set to 2000 rpm for 30 s, and then transferred to a 70°C hot stage for 10 min annealing to complete the preparation of the electron transport layer.

[0047] Step 7): Spin-coat 40 μL of isopropanol solution of BCP on the electron transport layer prepared in step 6), wherein the concentration of BCP in isopropanol is 0.5 mg / mL, and place it at 20°C for 20 min before spin coating. Set the spin coating speed to 4000 rpm for 30 s, and then transfer it to a hot stage at 70°C for 10 min annealing to complete the preparation of the hole blocking layer.

[0048] Step 8): After the hole blocking layer prepared in step 7) is left to stand for 1 hour, a 100 nm thick silver electrode is deposited by vacuum evaporation to complete the preparation of the tin-based perovskite solar cell.

[0049] The device prepared in Example 1 was exposed to simulated sunlight at 100 mW / cm 2 Under the light intensity of AM 1.5G, the measured JV curve is as follows Figure 1 As shown, the best photoelectric conversion efficiency is 8.95%.

[0050] Example 2

[0051] Step 1): Same as Example 1.

[0052] Step 2): Under a nitrogen atmosphere, methylamine bromide, formamidine iodine, stannous iodide, stannous fluoride, phenethyl ammonium iodide, tin powder, and 2-benzyl-2-isothiourea hydrochloride are mixed and dissolved in a N,N-dimethylformamide and dimethyl sulfoxide solvent with a volume ratio of 4:1, and stirred at 25°C for 8 hours, wherein the molar ratio of methylamine bromide, formamidine iodine, stannous iodide, stannous fluoride, phenethyl ammonium iodide, and tin powder is 0.25:0.75:1:0.1:0.135:0.04, the concentration of stannous iodide is 0.9M, and the addition amount of 2-benzyl-2-isothiourea hydrochloride is 0.5 mg / mL, which is dissolved in a N,N-dimethylformamide and dimethyl sulfoxide solvent with a volume ratio of 4:1 to obtain a tin-based perovskite precursor solution.

[0053] Step 3)-Step 8): Same as Example 1.

[0054] The device prepared in Example 2 was exposed to simulated sunlight at 100 mW / cm 2 Under the light intensity of AM 1.5G, the measured JV curve is as follows Figure 2 As shown in Figure 2, the best photoelectric conversion efficiency is 9.56%. After the unpackaged device is placed in nitrogen for 1500 hours, it still maintains more than 93.0% of the initial efficiency. Figure 6 shown.

[0055] Example 3

[0056] Step 1): Same as Example 1.

[0057] Step 2): Under a nitrogen atmosphere, methylamine bromide, formamidine iodine, stannous iodide, stannous fluoride, phenethyl ammonium iodide, tin powder, and 2-benzyl-2-isothiourea hydrochloride are mixed and dissolved in a N,N-dimethylformamide and dimethyl sulfoxide solvent with a volume ratio of 4:1, and stirred at 25°C for 8 hours, wherein the molar ratio of methylamine bromide, formamidine iodine, stannous iodide, stannous fluoride, phenethyl ammonium iodide, and tin powder is 0.25:0.75:1:0.1:0.135:0.04, the concentration of stannous iodide is 0.9M, and the concentration of 2-benzyl-2-isothiourea hydrochloride is 0.9mg / mL, to obtain a tin-based perovskite precursor solution.

[0058] Step 3)-Step 8): Same as Example 1.

[0059] The device prepared in Example 3 was exposed to simulated sunlight at 100 mW / cm 2 Under the light intensity of AM 1.5G, the measured JV curve is as follows Figure 3 As shown, the best photoelectric conversion efficiency is 9.15%.

[0060] Example 4

[0061] Step 1): ultrasonically clean the indium tin oxide transparent conductive glass with glass cleaning agent, deionized water, acetone, isopropyl alcohol and alcohol for 20 minutes each, and then put the cleaned indium tin oxide transparent conductive glass into a 60° C. oven for drying for more than 24 hours for use.

[0062] Step 2): Under a nitrogen atmosphere, methylamine bromide, formamidine iodine, stannous iodide, stannous fluoride, phenethyl ammonium iodide, tin powder, and 2-benzyl-2-isothiourea hydrochloride are mixed and dissolved in a N,N-dimethylformamide and dimethyl sulfoxide solvent with a volume ratio of 4:1, and stirred at 25°C for 8 hours, wherein the molar ratio of methylamine bromide, formamidine iodine, stannous iodide, stannous fluoride, phenethyl ammonium iodide, and tin powder is 0.25:0.75:1:0.1:0.135:0.04, the concentration of stannous iodide is 0.9M, and the concentration of 2-benzyl-2-isothiourea hydrochloride is 1.3 mg / mL, to obtain a tin-based perovskite precursor solution.

[0063] Step 3)-Step 8): Same as Example 1.

[0064] The device prepared in Example 4 was exposed to simulated sunlight at 100 mW / cm 2 Under the light intensity of AM 1.5G, the measured JV curve is as follows Figure 4 As shown, the best photoelectric conversion efficiency is 9.07%.

[0065] Comparative Example 1

[0066] In step 2) of this comparative example, 2-benzyl-2-isothiourea hydrochloride was not added, and the remaining operation steps and raw material amounts were the same as those in Example 2.

[0067] The device prepared in Comparative Example 1 was exposed to simulated sunlight at 100 mW / cm 2 Under the light intensity of AM 1.5G, the measured results are as follows Figure 5 As shown in Figure 2, the best photoelectric conversion efficiency is 8.55%. After the unpackaged device is placed in nitrogen for 1500 hours, it only maintains more than 73.7% of the initial efficiency. Figure 6 shown.

[0068] from Figure 6 It can be seen that the device in Example 2 has good stability, which is better than the device in Comparative Example 1, indicating that the modified tin-based perovskite light-absorbing layer is less likely to decompose in a nitrogen environment and can maintain its original performance for a long time.

[0069] from Figure 7 It can be seen that the absorbance of the tin-based perovskite film of Example 2 is better than that of Comparative Example 1 in the visible light region, indicating that the modified tin-based perovskite film has a higher light utilization rate, which may be due to the improvement of the crystallinity and density of the film.

[0070] from Figure 8 It can be seen that the Sn of the tin-based perovskite film in Example 2 4+ The strength is significantly lower than that of Comparative Example 1, Sn 2+ The strength is significantly higher than that of Comparative Example 1, indicating that the modification method used in the present invention can significantly inhibit the Sn in the tin-based perovskite film. 2+ Oxidation, thereby reducing the defect states caused by oxidation, Sn 4+ The reduction of means lower p-type doping.

[0071] from Fig. 9 It can be seen that the defect state density of the tin-based perovskite film of Example 2 is 2.94×10 15 cm -3 , which is significantly lower than 3.49×10 15 cm -3 , proving that the modification method of the present invention effectively reduces the defect state density of the tin-based perovskite film and improves the film quality.

[0072] from Fig.10 It can be seen that the dark current density of the device in Example 2 is about 2 orders of magnitude lower than that in Comparative Example 1, indicating that the defect density is significantly reduced, which is beneficial to charge transport in the film.

[0073] from Fig.11 It can be seen that the ideal factor of the device in Example 2 (n=1.74) is lower than that of the device in Comparative Example 1 (n=2.47), indicating that the modification method of the present invention reduces defect-assisted carrier recombination in the tin-based perovskite film, reduces energy loss, and is beneficial to improving the photoelectric conversion efficiency of the device.

[0074] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A tin-based perovskite precursor solution, characterized in that: The tin-based perovskite precursor solution contains 2-benzyl-2-isothiourea hydrochloride.

2. The tin-based perovskite precursor solution according to claim 1, characterized in that: The mass concentration of the 2-benzyl-2-isothiourea hydrochloride in the tin-based perovskite precursor solution is 0.2-1.3 mg / mL.

3. The tin-based perovskite precursor solution according to claim 1, characterized in that: The tin-based perovskite precursor solution also includes methylamine bromide, formamidine iodine, stannous iodide, stannous fluoride, phenethylammonium iodide, and tin powder; The molar ratio of methylamine bromide, formamidine iodine, stannous iodide, stannous fluoride, phenethylammonium iodide and tin powder is 0.25:0.75:1:0.1:0.135:0.04-0.05; The concentration of stannous iodide in the tin-based perovskite precursor solution is 0.9M.

4. The tin-based perovskite precursor solution according to claim 1, characterized in that: The solvent of the tin-based perovskite precursor solution is at least one of N,N-dimethylformamide and dimethyl sulfoxide.

5. A method for preparing a tin-based perovskite precursor solution according to any one of claims 1 to 4, characterized in that: The method comprises the following steps: uniformly dissolving 2-benzyl-2-isothiourea hydrochloride, methylamine bromide, formamidine iodine, stannous iodide, stannous fluoride, phenethylammonium iodide and tin powder in an organic solvent under a protective atmosphere, and stirring at 25-30° C. for 8-10 hours to obtain a tin-based perovskite precursor solution.

6. A method for preparing a light absorbing layer from the tin-based perovskite precursor solution according to any one of claims 1 to 4, characterized in that: Under a protective atmosphere, the tin-based perovskite precursor solution is coated on a substrate, an anti-solvent is added dropwise, and then annealed to obtain a light-absorbing layer.

7. The method for preparing a light absorbing layer from a tin-based perovskite precursor solution according to claim 6, characterized in that: The coating adopts a multi-step spin coating method, and the parameters are set to first rotate at a speed of 1000 rpm for 8 to 10 seconds, and then rotate at a speed of 6000 to 8000 rpm for 35 to 50 seconds; The anti-solvent addition time is 10 to 16 seconds of the second spin coating step; The annealing treatment is set to first anneal at 40-45° C. for 3-5 minutes, and then anneal at 80-85° C. for 10-20 minutes.

8. A tin-based perovskite solar cell, characterized in that: It comprises a substrate, a hole transport layer, a light absorbing layer, an electron transport layer, a hole blocking layer and an electrode layer which are stacked in sequence; the light absorbing layer is prepared by the method according to claim 6.

9. The tin-based perovskite solar cell according to claim 8, characterized in that: The substrate is indium tin oxide transparent conductive glass; And / or, the hole transport layer material is PEDOT:PSS; And / or, the electron transport layer material is PC 61 BM; And / or, the hole blocking layer material is 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline; The electrode layer material is silver.

Images