A method for alcohol-assisted chemical bath deposition of an electron transport layer for a perovskite solar cell and a perovskite solar cell

Abstract

The application discloses a method for alcohol-assisted chemical bath deposition of an electron transport layer of a perovskite solar cell and the perovskite solar cell, and the method comprises the following steps: cleaning a substrate to obtain a clean conductive glass substrate; adding SnCl2.2H2O into an isobutyl alcohol aqueous solution, then adding urea, and then adding mercaptoacetic acid and concentrated hydrochloric acid to mix, so as to complete preparation of a chemical bath solution; placing the clean substrate into the chemical bath solution to soak and depositing reaction in an oven, and then performing cleaning and annealing treatment after the reaction is completed, so as to complete deposition of a SnO2 electron transport layer on the conductive glass substrate. The SnO2 electron transport layer deposited by the method for alcohol-assisted chemical bath deposition of an electron transport layer is more uniform, the agglomeration of nanoparticles is reduced, the transmittance of sunlight is higher, the utilization rate of sunlight of the perovskite solar cell is improved, the open-circuit voltage and the short-circuit current density of the cell are reduced, and therefore the photoelectric conversion efficiency of the perovskite solar cell is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of perovskite solar cells, and particularly relates to a method for alcohol-assisted chemical bath deposition of an electron transport layer for a perovskite solar cell and the perovskite solar cell. BACKGROUND

[0002] In high-end equipment manufacturing industry, among new solar cells, perovskite solar cells (PSCs) have been widely concerned by the academic and industrial circles as one of the most promising technologies in recent years, and the photoelectric conversion efficiency (PCE) has broken through 26%. In the perovskite solar cell, the electron transport layer plays a crucial role in extracting electrons and hindering hole transport. At present, the commonly used electron transport layer is SnO2, which has high bulk electron mobility and high conductivity, a wider band gap (3.6-4.0 eV) and higher transmittance, and can be processed at low temperature and applied to flexible perovskite solar cells. However, the performance of SnO2 is closely related to its preparation method, and the commonly used preparation methods at present mainly include spin coating, atomic layer deposition and chemical bath deposition.

[0003] However, in the process of chemical bath deposition, SnO2 nanoparticles inevitably aggregate, resulting in uneven surface, reducing the effective contact area and thus reducing the electron transport efficiency; moreover, the aggregated SnO2 can introduce more defects at the interface with the perovskite layer, which will act as a center for charge recombination, increase non-radiative recombination, reduce the open-circuit voltage and short-circuit current density of the cell, and thus reduce the cell efficiency; in addition, SnO2 aggregation will also affect light scattering and reflection, reducing the amount of light absorbed by the perovskite layer, thus affecting the photocurrent and overall efficiency of the cell. SUMMARY

[0004] The present application provides a method for alcohol-assisted chemical bath deposition of an electron transport layer for a perovskite solar cell and the perovskite solar cell to solve the above problems.

[0005] To achieve the above-mentioned purposes, the technical scheme of the present application is as follows:

[0006] In one aspect, the present application provides a method for alcohol-assisted chemical bath deposition of an electron transport layer for a perovskite solar cell, comprising the following steps:

[0007] S1: cleaning the conductive glass substrate to obtain a clean conductive glass substrate;

[0008] S2: SnCl2.2H2O is added into the isobutyl alcohol aqueous solution to obtain a first mixed solution, urea is added into the first mixed solution to obtain a second mixed solution, then mercaptoacetic acid, concentrated hydrochloric acid and the second mixed solution are mixed to complete preparation of the chemical bath solution;

[0009] S3: the clean conductive glass substrate is immersed into the chemical bath solution and placed in an oven for deposition reaction, and after the reaction is completed, the conductive glass substrate is cleaned and annealed to complete deposition of the SnO2 electronic transport layer on the conductive glass substrate.

[0010] Further, in S2, the volume fraction of the isobutyl alcohol aqueous solution is 0-20%.

[0011] Further, in S2, the concentration of urea in the second mixed solution is 12-13 mg / mL.

[0012] Further, in S2, the concentration of SnCl2.2H2O in the first mixed solution is 2-3 mg / mL.

[0013] Further, in S2, the mercaptoacetic acid, concentrated hydrochloric acid and the mixed solution are mixed according to a volume ratio of 1:50:80.

[0014] Further, in S3, the annealing temperature is 100-200 DEG C, and the annealing time is 1-2 h.

[0015] Further, in S3, the temperature of the oven is 70-90 DEG C, and the time is 3-5 h.

[0016] Further, the conductive glass substrate is a fluorine-doped tin oxide conductive glass substrate.

[0017] Further, in S1, the specific cleaning method is: sequentially ultrasonic cleaning with washing-up liquid, deionized water, anhydrous ethanol and isopropyl alcohol for 15-30 min.

[0018] In S3, the specific cleaning method is: sequentially ultrasonic cleaning the substrate with deionized water and isopropyl alcohol for 5-10 min.

[0019] Another aspect of the present application provides a perovskite solar cell, comprising a conductive glass substrate, an electronic transport layer, a perovskite layer, a hole transport layer and an electrode layer arranged in a stack, wherein the electronic transport layer is prepared by the method for alcohol-assisted chemical bath deposition of an electronic transport layer for a perovskite solar cell.

[0020] The present application has the following advantages:

[0021] The method for alcohol-assisted chemical bath deposition of an electron transport layer for a perovskite solar cell disclosed in the application has better uniformity of the SnO2 electron transport layer deposited by alcohol-assisted chemical bath, reduced agglomeration of nanoparticles, and higher transmittance of sunlight, which is conducive to improving the sunlight utilization rate of the perovskite solar cell, and can also improve the open-circuit voltage and short-circuit current density of the cell, thereby improving the photoelectric conversion efficiency of the perovskite solar cell. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0023] Figure 1 SEM images of the surfaces of the four SnO2 electron transport layers prepared in Examples 1-3 and the comparative example of the present application (Fig. (a) is the SnO2 deposited by 5% volume fraction of isobutyl alcohol chemical bath; Fig. (b) is the SnO2 deposited by 10% volume fraction of isobutyl alcohol chemical bath; Fig. (c) is the SnO2 deposited by 20% volume fraction of isobutyl alcohol chemical bath; Fig. (d) is the SnO2 deposited by aqueous solution (without isobutyl alcohol) chemical bath);

[0024] Figure 2 UV spectrum results of the four SnO2 electron transport layers prepared in Examples 1-3 and the comparative example of the present application;

[0025] Figure 3 Current density-voltage curve of the perovskite solar cell prepared based on the SnO2 electron transport layer deposited by 5% volume fraction of isobutyl alcohol chemical bath in Example 1 of the present application;

[0026] Figure 4 Current density-voltage curve of the perovskite solar cell prepared based on the SnO2 electron transport layer deposited by 10% volume fraction of isobutyl alcohol chemical bath in Example 2 of the present application;

[0027] Figure 5 Current density-voltage curve of the perovskite solar cell prepared based on the SnO2 electron transport layer deposited by 20% volume fraction of isobutyl alcohol chemical bath in Example 3 of the present application;

[0028] Figure 6 Current density-voltage curve of the perovskite solar cell prepared based on the SnO2 electron transport layer deposited by aqueous solution (without isobutyl alcohol) chemical bath in the comparative example of the present application. DETAILED DESCRIPTION

[0029] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0030] The principle involved in the present application is that the hydroxyl group of isobutyl alcohol can form a coordination bond with tin ions in the deposition solution, and this coordination can reduce the reactivity and slow down the hydrolysis and aggregation rate. Moreover, isobutyl alcohol has an isobutyl structure, and there is a steric hindrance effect. This steric hindrance can prevent the mutual contact between SnO2 particles and slow down the aggregation rate. At the same time, isobutyl alcohol can be uniformly distributed in the solution, providing more active sites for the nucleation of SnO2, thereby increasing the nucleation density, reducing the aggregation of particles, and further improving the transmittance of sunlight, so that the sunlight utilization rate of the perovskite solar cell is improved, and finally the efficiency of the perovskite solar cell is improved.

[0031] EMBODIMENT

[0032] Embodiment 1

[0033] A method for alcohol-assisted chemical bath deposition of an electron transport layer for a perovskite solar cell, comprising the following steps:

[0034] S1: cleaning treatment of a transparent conductive substrate

[0035] A fluorine-doped tin oxide conductive glass substrate (FTO) was sequentially ultrasonically cleaned with detergent, deionized water, anhydrous ethanol and isopropanol for 15 min each.

[0036] S2: preparation of a chemical bath solution

[0037] 5 ml of isobutyl alcohol and 45 ml of water were mixed to obtain an isobutyl alcohol aqueous solution, and the volume fraction of isobutyl alcohol was 5%. Then 137.5 mg of SnCl2·2H2O was added to the isobutyl alcohol aqueous solution to obtain a first mixture, and the concentration of SnCl2·2H2O was 2.75 mg / mL. 625 mg of urea was added to the first mixture to obtain a second mixture, and the concentration of urea was 12.5 mg / mL. Then 12.5 uL of mercaptoacetic acid, 625 uL of concentrated hydrochloric acid and 1 ml of the second mixture were mixed and stirred until clear, and the preparation of the chemical bath solution was completed.

[0038] S3: chemical bath deposition of a SnO2 electron transport layer

[0039] The cleaned FTO was vertically placed into the chemical bath solution and was placed in a 90℃ oven for deposition reaction for 3.5h. After the reaction, the substrate was ultrasonically cleaned with deionized water and isopropanol for 5min, and then was annealed at 170℃ for 1h to complete the deposition of SnO2 electron transport layer on the FTO.

[0040] S4: A perovskite layer, a hole transport layer Spiro-OMeTAD and an electrode layer were sequentially deposited on the above SnO2 electron transport layer to prepare a perovskite solar cell, and the specific method was as follows:

[0041] Deposition of perovskite layer: MABr (8.4mg), PbBr2 (27.53mg), MACl (28.86mg), FAI (245.06mg), PbI2 (656.94mg) were dissolved in DMSO (125uL) and DMF (875uL) to obtain a perovskite precursor solution; 30uL of the perovskite precursor solution was dropped on the substrate on which SnO2 was deposited, and then a two-stage spin coating process (1000rpm for 10s and 3000rpm for 30s) was performed to spin coat the perovskite precursor solution; 200uL of anti-solvent chlorobenzene was continuously dropped on the rotating substrate 15s after the end of the second stage of spin coating, and then the prepared thin film was annealed at 120℃ for 40min to obtain a perovskite thin film (perovskite layer);

[0042] Deposition of hole transport layer Spiro-MeOTAD: 72.3mg of Spiro-MeOTAD, 17.5uL of LITFSI acetonitrile solution (520mg / mL), 20uL of FK209 acetonitrile solution (300mg / mL) and 28.8uL of tetra-tert-butylpyridine were dissolved in 1mL of chlorobenzene to obtain a hole transport layer precursor solution; 15uL of the hole transport layer precursor solution was dropped on the perovskite thin film, and spin coating was performed at 3000rpm for 30s to complete the preparation of the hole transport layer Spiro-MeOTAD;

[0043] Evaporation of metal electrode layer: the substrate with the hole transport layer Spiro-MeOTAD was fixed on a patterned mask, and then was placed in an evaporation chamber of a vacuum evaporation instrument, silver particles were placed on a tungsten boat, and then the evaporation chamber was evacuated to a vacuum state (<10 -3 Pa) for evaporation; the evaporation rate and thickness were controlled by a film thickness meter, the rate was about 0.2nm / s, the thickness of Ag was controlled at 70nm, the evaporation of silver electrode was completed, and a complete perovskite solar cell (PSCs device) was prepared.

[0044] Example 2:

[0045] A method for alcohol-assisted chemical bath deposition of an electron transport layer for a perovskite solar cell, comprising the following steps:

[0046] S1: cleaning and treatment of the transparent conductive substrate, same as in Example 1;

[0047] S2: preparation of the chemical bath solution, the difference from Example 1 is that the volume fraction of the isobutyl alcohol aqueous solution is 10%;

[0048] S3: chemical bath deposition of the SnO2 electron transport layer, same as in Example 1;

[0049] S4: sequentially depositing a perovskite layer and a hole transport layer Spiro-OMeTAD on the above SnO2 electron transport layer and evaporating a metal electrode layer to prepare a complete perovskite solar cell, the specific method is same as in Example 1.

[0050] Example 3:

[0051] A method for alcohol-assisted chemical bath deposition of an electron transport layer for a perovskite solar cell, comprising the following steps:

[0052] S1: cleaning and treatment of the transparent conductive substrate, same as in Example 1;

[0053] S2: preparation of the chemical bath solution, the difference from Example 1 is that the volume fraction of the isobutyl alcohol aqueous solution is 20%;

[0054] S3: chemical bath deposition of the SnO2 electron transport layer, same as in Example 1;

[0055] S4: sequentially depositing a perovskite layer and a hole transport layer Spiro-OMeTAD on the above SnO2 electron transport layer and evaporating a metal electrode layer to prepare a complete perovskite solar cell, the specific method is same as in Example 1.

[0056] Comparative Example:

[0057] A method for chemical bath deposition of an electron transport layer for a perovskite solar cell, comprising the following steps:

[0058] S1: cleaning and treatment of the transparent conductive substrate, same as in Example 1;

[0059] S2: preparation of the chemical bath solution, the difference from Example 1 is that the isobutyl alcohol is not contained in the chemical deposition solution;

[0060] S3: chemical bath deposition of the SnO2 electron transport layer, same as in Example 1;

[0061] Depositing perovskite layer and hole transport layer Spiro-OMeTAD and evaporating metal electrode layer on the SnO2 electron transport layer in sequence to prepare a complete perovskite solar cell, and the specific method is the same as that in Example 1.

[0062] Sample characterization and performance test:

[0063] (1) The SnO2 electron transport layers prepared in Examples 1-3 and Comparative Example S were respectively scanned by SEM, and the results are shown in Figure 1 (Figs. a, b, c, d are SEM scanning result graphs of Examples 1-3 and Comparative Example S, respectively), wherein the SnO2 electron transport layer prepared in the comparative example has uneven particle size, irregular particle shape and serious aggregation phenomenon; the SEM graph of the SnO2 electron transport layer of Example 1 shows relatively large particles and uneven distribution, showing a certain degree of particle aggregation phenomenon; the SnO2 electron transport layer of Example 2 has the best surface morphology, showing small and uniform particles, smooth and dense surface, regular particle shape and less aggregation phenomenon; the SnO2 particles in Example 3 have almost no aggregation behavior, but the SnO2 particles are relatively dispersed, and the particles are too small, resulting in that almost no SnO2 particles can be observed in the SEM graph.

[0064] (2) The SnO2 electron transport layers prepared in Examples 1-3 and Comparative Example S were respectively tested by ultraviolet-visible light spectrum, and the results are shown in Figure 2 Overall, the transmittance of the SnO2 electron transport layer of the comparative example is the lowest, the transmittance of Examples 1-3 is higher than that of the comparative example, and the transmittance of Example 2 is higher than that of Examples 1 and 3, which shows that the SnO2 electron transport layer prepared by the alcohol-assisted chemical bath deposition method effectively improves the transmittance of the SnO2 electron transport layer, and the SnO2 electron transport layer prepared by the 10% volume fraction of isobutyl alcohol in Example 2 has the best effect.

[0065] (3) The perovskite solar cells prepared in Examples 1-3 and Comparative Example S were respectively tested by current density-voltage test, and the test method was as follows: first, the light intensity was calibrated by using a standard silicon cell, so that the intensity was 100 mW·cm -2 The scanning voltage range was 0V-1.2V, the data collection time interval was 100ms, and the scanning speed was 200mV / s, and the test results are shown in Figures 3-6 and Table 1.

[0066] Table 1 Photovoltaic parameters of perovskite solar cells prepared based on SnO2 electron transport layers of Examples 1-3 and Comparative Example S (obtained from the corresponding current density-voltage curves)

[0067] Sample Photoelectric conversion efficiency Open circuit voltage Short circuit current density Fill factor Example 1 20.83％ 1.13V 23.03 mA / cm 2 ]] 79.69％ Example 2 22.05％ 1.13V 24.16 mA / cm 2 ]] 80.67％ Example 3 21.17％ 1.13V <![CDATA[23.55mA / cm 2 ]]> 79.78％ Comparative Example 20.26％ 1.11V 22.74 mA / cm 2 ]]> 80.16％

[0068] Figure 3 The current density-voltage curve of the perovskite solar cell prepared by SnO2 deposited from the 5% volume fraction of isobutyl alcohol chemical bath in Example 1 is shown in Figure 1, and the open circuit voltage, short circuit current density and fill factor of the Example 1 cell are 1.13 V, 23.03 mA / cm2and 79.69%, respectively. Figure 3 As shown in Figure 1 and Table 1, the open circuit voltage of the Example 1 cell is 1.13 V, the short circuit current density is 23.03 mA / cm2, and the fill factor is 79.69%. 2 Figure 4 The current density-voltage curve of the perovskite solar cell prepared by SnO2 deposited from the 10% volume fraction of isobutyl alcohol chemical bath in Example 2 is shown in Figure 2, and the open circuit voltage, short circuit current density and fill factor of the Example 2 cell are 1.13 V, 24.16 mA / cm2and 80.67%, respectively. Figure 4 As shown in Figure 2 and Table 1, the open circuit voltage of the Example 2 cell is 1.13 V, the short circuit current density is 24.16 mA / cm2, and the fill factor is 80.67%. 2 Figure 5 The current density-voltage curve of the perovskite solar cell prepared by SnO2 deposited from the 20% volume fraction of isobutyl alcohol chemical bath in Example 3 is shown in Figure 3, and the open circuit voltage, short circuit current density and fill factor of the Example 3 cell are 1.13 V, 23.55 mA / cm2and 79.78%, respectively. Figure 5 As shown in Figure 3 and Table 1, the open circuit voltage of the Example 3 cell is 1.13 V, the short circuit current density is 23.55 mA / cm2, and the fill factor is 79.78%. 2 Figure 6 The current density-voltage curve of the perovskite solar cell prepared by SnO2 deposited from the water solution (without isobutyl alcohol) chemical bath in the Comparative Example is shown in Figure 4, and the open circuit voltage, short circuit current density and fill factor of the Comparative Example cell are 1.11 V, 22.74 mA / cm2and 80.16%, respectively. Figure 6 As shown in Figure 4 and Table 1, the open circuit voltage of the Comparative Example cell is 1.11 V, the short circuit current density is 22.74 mA / cm2, and the fill factor is 80.16%. 2 The photoelectric conversion efficiency, open circuit voltage and short circuit current density of the perovskite solar cells prepared in Examples 1-3 are all higher than those of the Comparative Example, indicating that the electron transport layer prepared by the alcohol-assisted chemical bath deposition method provided by the present application applied in the preparation of perovskite solar cells can effectively improve the open circuit voltage and short circuit current of the perovskite solar cells, thereby improving the photoelectric conversion efficiency of the perovskite solar cells.

[0069] In summary, the SnO2 electron transport layer prepared by the alcohol-assisted chemical bath deposition method provided by the present application has uniform SnO2 particle distribution, reduced agglomeration, high solar light transmittance, improved solar light utilization rate of the perovskite solar cells, improved open circuit voltage and short circuit current of the prepared perovskite solar cells, and improved photoelectric conversion efficiency. In addition, the reduction of SnO2 agglomeration can improve the stability of the cell and reduce the inconsistency of the performance between different batches of SnO2 layers, thereby reducing the control difficulty and the production cost.

[0070] ​​​It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions recorded in the above embodiments can be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for alcohol-assisted chemical bath deposition of an electron transport layer for perovskite solar cells, characterized in that: The following steps are involved: S1: Cleaning the conductive glass substrate to obtain a clean conductive glass substrate; S2: adding SnCl2·2H2O to an isobutanol aqueous solution to obtain a first mixed solution, adding urea to the first mixed solution to obtain a second mixed solution, and then mixing thioglycolic acid, concentrated hydrochloric acid, and the second mixed solution to complete the preparation of the chemical bath solution; S3: Soak the clean conductive glass substrate in a chemical bath solution and place it in an oven for deposition reaction. After the reaction is completed, clean and anneal the conductive glass substrate to complete the deposition of the SnO2 electron transport layer on the conductive glass substrate.

2. The method for alcohol-assisted chemical bath deposition of an electron transport layer for a perovskite solar cell according to claim 1, characterized in that: In S2, the volume fraction of the isobutanol aqueous solution is 0-20% and greater than 0.

3. The method for alcohol-assisted chemical bath deposition of an electron transport layer for a perovskite solar cell according to claim 1, characterized in that: In S2, the concentration of urea in the second mixed solution is 12-13 mg / mL.

4. The method for alcohol-assisted chemical bath deposition of an electron transport layer for a perovskite solar cell according to claim 1, characterized in that: In S2, the concentration of SnCl2·2H2O in the first mixed solution is 2-3 mg / mL.

5. The method for alcohol-assisted chemical bath deposition of an electron transport layer for a perovskite solar cell according to claim 1, characterized in that: In S2, the thioglycolic acid, concentrated hydrochloric acid and the second mixed solution are mixed in a volume ratio of 1:50:

80.

6. The method for alcohol-assisted chemical bath deposition of an electron transport layer for a perovskite solar cell according to claim 1, characterized in that: In S3, the annealing temperature is 100-200° C., and the annealing time is 1-2 hours.

7. The method for alcohol-assisted chemical bath deposition of an electron transport layer for a perovskite solar cell according to claim 1, characterized in that: In S3, the temperature of the oven is 70-90°C and the time is 3-5 hours.

8. The method for alcohol-assisted chemical bath deposition of an electron transport layer for a perovskite solar cell according to claim 1, characterized in that: The conductive glass substrate is a fluorine-doped tin oxide conductive glass substrate.

9. The method for alcohol-assisted chemical bath deposition of an electron transport layer for a perovskite solar cell according to claim 1, characterized in that: In S1, the specific cleaning method is: ultrasonic cleaning with detergent, deionized water, anhydrous ethanol, and isopropyl alcohol for 15-30 minutes each; In S3, the specific cleaning method is: ultrasonically clean the substrate with deionized water and isopropyl alcohol in sequence for 5-10 minutes.

10. A perovskite solar cell, characterized in that: The invention comprises a conductive glass substrate, an electron transport layer, a perovskite layer, a hole transport layer and an electrode layer stacked in sequence, wherein the electron transport layer is an electron transport layer prepared by the method for alcohol-assisted chemical bath deposition of an electron transport layer for a perovskite solar cell according to any one of claims 1 to 9.

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