Electron transport layer and perovskite thin film structure and preparation method thereof

Abstract

The invention relates to the technical field of perovskite thin films, in particular to an electron transport layer and perovskite thin film structure and a preparation method thereof.The electron transport layer and perovskite thin film structure comprises an electron transport layer, a sulfate modified layer and a perovskite layer, the electron transport layer, the sulfate modified layer and the perovskite layer are included, the sulfate modified layer is prepared through a sulfate solution, and the sulfate modified layer is prepared through a sulfate solution. The sulfate solution is cesium sulfate, ammonium sulfate or potassium sulfate solution. The adopted salt passivator is economical and environmentally friendly, surface defects are reduced through the reaction of acidic sulfate ions and SnO2, and meanwhile, Cs < + > is used for filling defect sites and adjusting the Fermi level. Through the preparation of the sulfate layer, the carrier transport kinetics of SnO2ETL is improved, the quality of the perovskite film is improved, ion migration is inhibited, and the treatment condition is simple.

Description

Technical Field

[0001] The present invention relates to the technical field of perovskite thin films, and in particular to an electron transport layer and perovskite thin film structure and a preparation method thereof. Background Art

[0002] Current SnO 2 PSCs still have problems of low carrier extraction efficiency and poor quality of perovskite films, which leads to severe recombination losses, thus limiting their theoretical efficiency. In addition, the relevant research strategies of the existing technology mainly focus on solving the problem of SnO 2 Or the problem of the existence of the perovskite layer alone has not been effectively explored in depth for the coordinated optimization of the two functional layers. 2 The performance of ETL and perovskite layers remains a pressing technological challenge. Summary of the invention

[0003] The purpose of the present invention is to provide an electron transport layer and perovskite film structure and a preparation method thereof, so as to solve the technical problem that there is no good method in the prior art to optimize the synergy of the two functional layers.

[0004] The invention discloses an electron transport layer and perovskite film structure, comprising an electron transport layer, a sulfate modification layer and a perovskite layer. The sulfate modification layer is prepared by a sulfate solution, and the sulfate solution is a cesium sulfate, ammonium sulfate or potassium sulfate solution.

[0005] A method for forming an electron transport layer and a perovskite film structure, wherein a sulfate modification layer is prepared between the electron transport layer and the perovskite layer, wherein the sulfate modification layer is prepared by a sulfate solution, and the sulfate solution is a cesium sulfate, ammonium sulfate or potassium sulfate solution.

[0006] Furthermore, the concentration of the sulfate solution is 0.5-7 mg / mL.

[0007] Furthermore, the sulfate solution is spin-coated at a spin-coating parameter of 2000-4000 rpm.

[0008] Furthermore, after the sulfate solution is spin-coated, annealing is performed to obtain a sulfate modification layer.

[0009] Furthermore, the annealing is performed on a hot plate at 100-150° C. for 5-15 min.

[0010] Furthermore, the electron transport layer is SnO 2 Electron transport layer.

[0011] Furthermore, the electron transport layer is spin-coated on the conductive glass.

[0012] Furthermore, the perovskite layer is prepared using a two-step method.

[0013] Furthermore, a hole transport layer is prepared on the perovskite layer.

[0014] Furthermore, a silver electrode is prepared on the hole transport layer.

[0015] A perovskite solar cell comprises conductive glass or conductive glass FTO, an electron transport layer, a sulfate modification layer, a perovskite layer, a hole transport layer and a silver electrode in sequence, wherein the sulfate modification layer is prepared by a sulfate solution, and the sulfate solution is a cesium sulfate, ammonium sulfate or potassium sulfate solution.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. The salt passivating agent used in the present invention is economical and environmentally friendly. 2 The reaction of Cs + Fill the defect sites and adjust the Fermi level. The preparation of the sulfate layer not only improves the SnO 2 The carrier transport kinetics of ETL improves the quality of perovskite films, suppresses ion migration, and has simple processing conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only represent some embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 The present invention is based on SnO 2 / Cs 2 SO 4 Schematic diagram of perovskite deposition on a substrate.

[0020] Figure 2 For comparative example 1 of the present invention ( Figure 2 a) Example 1 ( Figure 2 c), Example 2 ( Figure 2 d) and Example 3 ( Figure 2 b) SEM image of the perovskite film. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0022] Example 1

[0023] This embodiment discloses an electron transport layer and a perovskite film structure, including the following steps:

[0024] (1) Cleaning ITO conductive glass

[0025] First, use a glass cutter to number the ITO glass sheets, then use glass cleaner, deionized water, analytical pure isopropanol, and anhydrous ethanol to ultrasonically clean them for 15 minutes, and then soak them in anhydrous ethanol for subsequent use.

[0026] (2) Preparation of electron transport layer

[0027] A 15% tin oxide colloidal aqueous solution was mixed with ultrapure water at a volume ratio of 1:4 and subjected to ultrasonic treatment for 20 minutes. The cleaned ITO glass sheet was blown dry with nitrogen and placed face up in a culture dish. After 15 minutes of UV-ozone treatment, 90uL of the prepared SnO 2 The solution was evenly coated on the ITO conductive glass, and the coating parameters were set to 4000rpm@2000rpm / s@20s using a coating machine to start the spin coating. Finally, the spin-coated film was annealed on a hot plate at 180℃ for 20min to form a dense SnO 2 Electron transport layer.

[0028] (3) Sulfate modified layer

[0029] Take 80uL of 3mg / mL cesium sulfate solution and apply it on the dense SnO 2 After the spin coating was completed at 3000 rpm, the SnO 2 / cesium sulfate electron transport layer.

[0030] (4) Preparation of perovskite layer

[0031] This paper adopts a two-step method to prepare the perovskite light absorption layer. First, the perovskite precursor solution needs to be prepared. The specific method is as follows: 0.6915g of PbI 2Add 1mL of DMF / DMSO mixed solvent (volume ratio 9:1), then place on a 70℃ hot plate until completely dissolved; dissolve 180mg:18mg of FAI:MACl in 2mL of IPA solution, add a stir bar and stir magnetically at room temperature for 12h. Then filter the prepared perovskite precursor solution with a polytetrafluoroethylene filter head with a pore size of 0.22um and set aside.

[0032] The first step is to take 50uL of PbI 2 On SnO treated with UV-ozone for 20 min 2 The film was spin-coated at 1500 rpm @ 1500 rpm / s @ 30 s, and then annealed at 70 ° C for 10 s to form PbI 2 The film was then spin-coated with 90uL of FAI solution in the second step, with the spin-coating parameters of 2000rpm@2000rpm / s@30s. When the film turned from bright red to dark orange in the glove box, it was transferred to the indoor air environment (RH=30%~40%) and annealed at 150℃ for 15min to complete the preparation of the perovskite film.

[0033] (5) Preparation of hole transport layer

[0034] Take 72.3 mg of Spiro-OMeTAD and add it to 1 mL of chlorobenzene solution, then add 28.8 uL of tert-butylpyridine and 17.5 uL of lithium salt acetonitrile solution (520 mg / mL), mix and let stand for 12 hours, then filter and set aside. Use a pipette to take 45 uL of the prepared Spiro-OMeTAD solution and spread it on the perovskite film, and spin coat it at 4000 rpm@3000 rpm / s@30s. The spin-coated film is placed in a vacuum drying oven in an oxygen atmosphere and oxidized at 40°C for 4 hours.

[0035] (6) Evaporated silver electrode

[0036] Use a scalpel to scrape off the perovskite film where the negative electrode is to be plated, and then -4 Pa, the silver electrode was evaporated. During the evaporation process, the silver deposition rate was controlled at The thickness of the silver electrode is about 100 nm.

[0037] Embodiment 2:

[0038] The only difference between this embodiment and embodiment 1 is that the cesium sulfate solution in step (3) is replaced by ammonium sulfate solution.

[0039] Embodiment 3:

[0040] The only difference between this embodiment and embodiment 1 is that the cesium sulfate solution in step (3) is replaced by ammonium sulfate solution.

[0041] Comparative Example 1:

[0042] The only difference between this comparative example and Example 1 is that no cesium sulfate modification layer is prepared.

[0043] Comparative Example 2:

[0044] The only difference between this comparative example and Example 1 is that the concentration of the prepared cesium sulfate modification layer is 10 mg / mL.

[0045] On a JV test instrument, 0.105 square centimeters of perovskite solar cells provided in the embodiment and the comparative example were tested based on a standard light intensity of one sun. The starting voltage of the JV test was set to 1.2 V, the ending voltage was set to -0.2 V, the scanning step was 0.02 V, and the delay time was set to 20 ms.

[0046] The above embodiments and comparative examples were tested for performance and the test results are shown in Figure 1:

[0047] <![CDATA[V OC (V)]]> <![CDATA[J SC (mA / cm 2 )]]> FF(%) PCE(%) Example 1 1.12 25.06 78.61 22.09 Example 2 1.12 24.98 78.43 21.86 Example 3 1.10 25.25 78.76 21.82 Comparative Example 1 1.11 24.66 76.66 21.01 Comparative Example 2 1.09 24.52 74.21 19.8

[0048] Among them, V OC -Open circuit voltage; J SC -short circuit current density; FF-fill factor; PCE-photovoltaic conversion efficiency.

[0049] The principle of the present invention is as follows Figure 1 As shown by Figure 2 From Table 1, we can get that 2 SO 4 Modified devices, FF and J SC The average value is 76.66% and 24.60 mA cm-1 of Comparative Example 1. -2 Improved to 78.61% and 25.06 mA cm -2 , PCE also increased from 21.01% to 22.09%. These results indicate that cesium sulfate interface modification can reduce defect density and inhibit non-radiative recombination, thereby promoting carrier transport capability.

[0050] We used SEM to conduct the corresponding test, and the results are as follows Figure 2 As shown in (ad), more PbI can be observed on the surface of the perovskite film in the control group. 2 The deposition is due to the PbI 2 Excessive addition of PbI 2 The addition of PbI to perovskite films is a double-edged sword. 2 It can passivate the grain boundaries, effectively reduce the recombination of charge carriers, and improve the initial performance of the device; on the other hand, the excess PbI2 It will decompose during device operation, and this decomposition will affect the overall stability of the perovskite layer. 2 SO 4 and (NH 4 ) 2 SO 4 The microscopic morphology of the perovskite film grown on the layer is smoother, and there is no obvious difference in grain size with the standard, but bright white areas, namely PbI 2 The gradual decrease of Figure 2 In (c), it can be observed that the 2 SO 4 The perovskite grain size of the modified samples increases.

[0051] The above are the implementation methods listed in this embodiment, but this embodiment is not limited to the above optional implementation methods. Those skilled in the art can arbitrarily combine the above methods to obtain other various implementation methods. Anyone can derive other various forms of implementation methods under the inspiration of this embodiment. The above specific implementation methods should not be understood as limiting the scope of protection of this embodiment. The scope of protection of this embodiment shall be based on the definition in the claims, and the description can be used to interpret the claims.

Claims

1. An electron transport layer and perovskite film structure, characterized in that: The invention comprises an electron transport layer, a sulfate modification layer and a perovskite layer. The sulfate modification layer is prepared by a sulfate solution, and the sulfate solution is a cesium sulfate, ammonium sulfate or potassium sulfate solution.

2. A method for preparing an electron transport layer and a perovskite thin film structure, characterized in that: A sulfate modification layer is prepared between the electron transport layer and the perovskite layer. The sulfate modification layer is prepared by a sulfate solution, and the sulfate solution is a cesium sulfate, ammonium sulfate or potassium sulfate solution.

3. The method for preparing an electron transport layer and a perovskite thin film structure according to claim 2, characterized in that: The concentration of the sulfate solution is 0.5-7 mg / mL.

4. The method for preparing an electron transport layer and a perovskite thin film structure according to claim 2, characterized in that: The sulfate solution was spin coated at a spin coating parameter of 2000-4000 rpm.

5. The method for preparing an electron transport layer and a perovskite thin film structure according to claim 2, characterized in that: After the sulfate solution is spin-coated, annealing is performed to obtain a sulfate modification layer.

6. The method for preparing an electron transport layer and a perovskite thin film structure according to claim 5, characterized in that: The annealing is performed on a hot plate at 100-150° C. for 5-15 minutes.

7. The method for preparing an electron transport layer and a perovskite thin film structure according to claim 2, characterized in that: The electron transport layer is a SnO2 electron transport layer.

8. The method for preparing an electron transport layer and a perovskite thin film structure according to claim 2, characterized in that: The electron transport layer is spin-coated on the ITO conductive glass.

9. The method for preparing an electron transport layer and a perovskite thin film structure according to claim 2, characterized in that: The perovskite layer is prepared using a two-step process.

10. A perovskite solar cell, characterized in that: The invention comprises conductive glass, an electron transport layer, a sulfate modification layer, a perovskite layer, a hole transport layer and a silver electrode in sequence. The sulfate modification layer is prepared by a sulfate solution, and the sulfate solution is a cesium sulfate, ammonium sulfate or potassium sulfate solution.

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