Perovskite battery and preparation method thereof

Abstract

The invention provides a perovskite battery and a preparation method thereof. A layer of dynamic self-repairing interface material is inserted between a hole transport layer and a perovskite active layer of the perovskite cell; the dynamic self-repairing interface material is formed by crosslinking lipoic acid and polyethyleneimine according to a certain ratio. According to the perovskite battery provided by the invention, the in-situ self-repairing of the perovskite active layer interface is realized through the dynamic interaction between the disulfide bond of the lipoic acid in the dynamic self-repairing interface material and the amino group in the polyethyleneimine. Meanwhile, according to the dynamic self-repairing interface material, the interface potential barrier is reduced through the molecular dipole effect, the charge extraction efficiency is improved, dangling bonds on an interface are neutralized through carboxylic acid groups of lipoic acid, the non-radiative recombination loss is reduced, and the photoelectric conversion efficiency is improved. Amino functional groups rich in the compound can form stable coordinate bonds with uncoordinated Pb on an interface, and deep energy level defects are passivated. The perovskite cell obtained through the technical scheme of the invention can improve the service life and the power generation efficiency.

Description

Technical Field

[0001] The present application relates to the field of production and manufacturing of perovskite cells or perovskite films, and specifically to a perovskite cell and a method for preparing the same. Background Art

[0002] Perovskite Solar Cells (PSCs) have become an important carrier for the development of next-generation photovoltaic technology due to their high photoelectric conversion efficiency, low-cost preparation, flexibility, and light weight.

[0003] At present, perovskite cells still face some key problems that need to be solved in practical applications. For example, under conditions such as thermal stress or environmental aging, polycrystalline perovskite layers are prone to form defects such as Pb²⁺ dangling bonds and I⁻ vacancies at the interface, leading to non-radiative recombination and ion migration, affecting the photoelectric performance and stability of the battery; the difference in thermal expansion coefficients between the substrate and the perovskite layer causes microcracks at the interface, accelerating water and oxygen penetration and device performance attenuation. In addition, perovskite materials are prone to chemical decomposition and structural degradation under the influence of environmental factors such as light and high temperature, which manifests as physical damage such as lattice expansion and contraction, further aggravating ion migration and defect formation, and ultimately leading to a significant decrease in the power generation efficiency of perovskite cells and a shortened lifespan.

[0004] In order to improve the power generation efficiency of perovskite cells, passivation materials are usually used to modify the interface of the perovskite active layer, which can passivate the interface of the perovskite active layer and even reduce defects such as Pb²⁺ dangling bonds and I⁻ vacancies. Existing passivation materials (such as PEAI, BAI, OACl, etc.) usually only play a passivation role and cannot self-repair the perovskite active layer after it is damaged. The damage to the perovskite active layer requires the use of special dynamic self-repairing materials. Existing dynamic self-repairing materials are generally dynamic covalent polymers, and perovskite active materials are mostly introduced by doping. However, this doping method not only easily destroys the crystallinity of the perovskite material, increases the complexity of the process, and cannot take into account the luminous efficiency and stability of the device, but also has a complex synthesis process and high cost.

[0005] In addition, in order to make up for the difference in thermal expansion coefficients between the substrate and the perovskite layer, a research team from East China University of Science and Technology recently successfully developed an ultra-thin protective layer, a substrate made of hard graphene and a special transparent plastic. The thickness of this protective layer is only one ten-thousandth of a hair, and by increasing the material's compressive resistance, it effectively reduces the expansion of the substrate caused by light. Experiments show that the use of this new protective layer allows the perovskite battery to maintain a power generation efficiency of 97% after working continuously for 3670 hours under strong light and high temperature, greatly increasing the possibility of its practical application. The substrate is mainly physically enhanced by the graphene protective layer to resist the influence of the external environment.

[0006] In summary, the existing passivation materials, dynamic self-healing materials and corresponding protective layers can only focus on solving one type of problem in the practical application of perovskite cells, and cannot improve the stability, life and power generation efficiency of perovskite cells in multiple aspects (for example, interface passivation, defect reduction, dynamic self-healing and electron extraction efficiency). Therefore, it is of great significance to develop a dynamic self-healing material that can improve the power generation efficiency and stability of perovskite cells without damaging the perovskite active layer, which is of great significance to the research and industrialization of perovskite photovoltaic modules. Summary of the invention

[0007] In order to solve the various problems of perovskite cells in practical applications and improve the power generation efficiency and stability of perovskite cells without damaging the perovskite active layer, the present application provides a perovskite cell and a preparation method thereof. The perovskite cell mainly inserts a layer of special dynamic self-repairing material between the hole transport layer and the perovskite active layer, and works together in the chemical dynamic repair, interface passivation, defect reduction, and improvement of electron extraction efficiency of the perovskite active layer to achieve the improvement of the stability and power generation efficiency of the perovskite cell.

[0008] The first aspect of the present application provides a perovskite battery. The perovskite battery has a dynamic self-repairing interface layer between a hole transport layer and a perovskite active layer, and the self-repairing material used in the dynamic self-repairing interface layer is formed by cross-linking lipoic acid and polyethyleneimine.

[0009] Furthermore, the self-healing material is prepared by dissolving lipoic acid and polyethyleneimine in a mixed solvent of ethanol and deionized water in a molar mass ratio of 1:1-1:3, and adding a crosslinking accelerator ZnCl 2 In one embodiment, the total concentration of the mixed solvent is 0.1 mg / mL-0.5 mg / mL, wherein the volume ratio of ethanol to deionized water is 2:1; the crosslinking accelerator ZnCl 2 The content is 0.1wt%-0.3wt%.

[0010] Preferably, the thickness of the dynamic self-healing interface layer is 5nm-20nm, and the thickness of the perovskite active layer is 400nm-600nm.

[0011] In terms of improving the stability and life of perovskite cells, the above self-healing material can achieve in-situ self-repair of the interface of the perovskite active layer based on the dynamic interaction between the disulfide bonds of lipoic acid and the amino groups in polyethyleneimine. In terms of improving the power generation efficiency of perovskite cells, the self-healing material can play a role in the following aspects: reducing the interface barrier and improving the charge extraction efficiency (carrier mobility is increased by about 20%-30%) through the molecular dipole effect; neutralizing the dangling bonds on the interface through the carboxylic acid group (-COOH) of lipoic acid to reduce non-radiative recombination losses; the amino functional groups rich in polyethyleneimine form stable coordination bonds with the uncoordinated Pb²⁺ on the interface to passivate deep energy level defects.

[0012] Corresponding to the above-mentioned perovskite battery, the second aspect of the present application provides a method for preparing a perovskite battery. The method comprises: sequentially stacking a hole transport layer, a dynamic self-repairing interface layer, a perovskite active layer, and an electron transport layer on a conductive substrate; the self-repairing material used in the dynamic self-repairing interface layer is obtained by cross-linking lipoic acid and polyethyleneimine.

[0013] Furthermore, the self-healing material is prepared by the following method: lipoic acid and polyethyleneimine (PEI) are mixed in a molar mass ratio of 1:1-1:3 and dissolved in a mixed solvent of ethanol and deionized water, and a cross-linking accelerator ZnCl is added. 2 In one embodiment, the total concentration of the mixed solvent is 0.1 mg / mL-0.5 mg / mL, the volume ratio of ethanol to deionized water is 2:1, and the crosslinking accelerator ZnCl 2 The content is 0.1wt%-0.3wt%.

[0014] Furthermore, the dynamic self-repairing interface layer is formed by coating the self-repairing material on the hole transport layer through a slit, volatilizing, and annealing. In some embodiments, the thickness of the dynamic self-repairing interface layer is set to 5nm-20nm, the conductive substrate is set to transparent conductive glass or flexible PET substrate, and the hole transport layer is set to NiO with a thickness of 20nm-50nm. x , PEDOT:PSS or Spiro-OMeTAD. Furthermore, the preparation of the perovskite active layer includes: dissolving a perovskite precursor solution in a solvent prepared by DMF and DMSO in a volume ratio of 4:1 to prepare a perovskite active material; coating the perovskite active material on the hole transport layer, vacuum flash evaporating for a first preset time, and annealing for a second preset time under specific annealing conditions to form a 400nm-600nm dense perovskite film.

[0015] In addition, in order to form a fully functional perovskite battery, the method further includes: sequentially stacking an electron transport layer, a hole blocking layer and a back electrode on the perovskite active layer.

[0016] The technical solution provided in this application greatly improves the power generation efficiency and working stability of perovskite solar cells by using specially made dynamic self-repairing interface materials to damage the perovskite active layer, optimize interface contact, reduce interface defects, and improve the charge extraction efficiency through the molecular dipole electric field. The technical solution provided in this application can be used not only to prepare rigid perovskite photovoltaic modules, but also to prepare flexible perovskite photovoltaic modules, greatly expanding the application prospects of perovskite solar cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 Schematic diagram of the structure of the perovskite battery provided in this application.

[0019] Figure 2a In one embodiment, the present application provides a SEM image of the perovskite active layer of the perovskite battery before the self-repair verification thermal damage repair experiment.

[0020] Figure 2b for Figure 2a In the illustrated embodiment, a SEM image of the perovskite active layer after thermal stress damage during the self-repair verification thermal damage repair process is shown.

[0021] Figure 2c , Figure 2d , Figure 2e These are the SEM images of the self-repair results of the perovskite active layer corresponding to the molar mass ratios of lipoic acid (TA) and polyethyleneimine (PEI) in the self-healing material of 1:1, 1:2, and 1:3, respectively.

[0022] Figure 3 The JV curves obtained by simulating thermal damage to perovskite battery components made of self-healing materials based on lipoic acid (TA) and polyethyleneimine (PEI) in molar mass ratios of 1:1, 1:2, and 1:3, respectively, and then testing them after self-repair.

[0023] Figure 4In one embodiment, the JV curves of the perovskite battery component and the perovskite battery component without a dynamic self-healing interface layer provided in the present application were tested after simulating thermal damage and post-treated at 40° C. for 48 hours.

[0024] Figure 5a , Figure 5b In one embodiment, the JV curve is obtained by testing the perovskite battery assembly provided by the present invention after self-repair after post-treatment at 40°C and 25°C, 40°C and 80°C for 48h (the post-treatment time is 1-72 hours, preferably 48 hours) after thermal damage. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0026] like Figure 1 In the embodiment shown, the perovskite battery provided by the present application has, from bottom to top, a conductive substrate 1, a hole transport layer 2, a dynamic self-repairing interface layer 3, a perovskite active layer 4, an electron transport layer 5, a hole blocking layer 6 and a back electrode 7. The dynamic self-repairing interface layer 3 is between the hole transport layer 2 and the perovskite active layer 4. Different from the existing self-repairing materials, the self-repairing material used in the dynamic self-repairing interface layer 3 is obtained by cross-linking lipoic acid and polyethyleneimine in corresponding proportions: lipoic acid and polyethyleneimine are dissolved in a mixed solvent of ethanol and deionized water in a molar mass ratio of 1:1-1:3, and a cross-linking promoter ZnCl is added. 2 Then stir it.

[0027] In one embodiment, the total concentration of the mixed solvent is 0.1-0.5 mg / mL, wherein the volume ratio of ethanol to deionized water is 2:1; the crosslinking accelerator ZnCl 2 The content is 0.1wt%-0.3wt%. The thickness of the dynamic self-repairing interface layer is 5-20nm, and the thickness of the perovskite active layer is 400-600nm.

[0028] The self-healing material used in the dynamic self-healing interface layer 3 in the above-mentioned perovskite battery mainly improves the stability and power generation efficiency of the perovskite battery through the following mechanism: Based on the dynamic interaction between the disulfide bonds of lipoic acid in the self-healing material and the amino groups in polyethyleneimine, the in-situ self-healing of the interface of the perovskite active layer is achieved, which can effectively improve the damage resistance, working stability and life of the perovskite battery.

[0029] The self-healing material improves the power generation efficiency of perovskite batteries through the following multiple effects: reducing the interface barrier and improving the charge extraction efficiency (carrier mobility is increased by about 20%-30%) through the molecular dipole effect; neutralizing the dangling bonds on the interface through the carboxylic acid group (-COOH) of thioctic acid to reduce non-radiative recombination losses; the amino functional groups rich in polyethyleneimine form stable coordination bonds with uncoordinated Pb²⁺ on the interface to passivate deep energy level defects.

[0030] Experimental results show that after the perovskite solar cell with the above structure is annealed at 40-60°C after thermal damage, the dynamic disulfide bonds are reorganized to repair the interface microcracks, and the amino groups of PEI re-form a hydrogen bond network with the perovskite surface, restoring the initial efficiency to about 97%.

[0031] In one embodiment, the above-mentioned perovskite cell (taking the inverted structure perovskite cell as an example) provided by the present application can be prepared by the following steps: S1. Prepare a conductive substrate. The conductive substrate can be selected as ITO / FTO transparent conductive glass or a flexible PET substrate, that is, the perovskite cell provided in this application can be a rigid solar cell or a flexible solar cell.

[0032] S2. Prepare a hole transport layer (HTL) on the conductive substrate. The material used for the hole transport layer is NiO x , PEDOT:PSS or Spiro-OMeTAD, with a thickness of 20-50nm.

[0033] S3. The prefabricated self-healing material is coated on the hole transport layer by a coating process to prepare a dynamic self-healing interface layer. The thickness of the self-healing interface layer can be set to 5-20 nm. The specific coating process can be slit coating, with a coating gap of 70-160 μm, a coating speed of 5-30 mm / s, a solvent evaporation time of 30-120 s, an annealing temperature of 80-120°C, and an annealing time of 5-20 min.

[0034] In this embodiment, the self-healing material can be prepared by the following method: pre-preparing a mixed solvent of ethanol and deionized water with a total concentration of 0.1-0.5 mg / mL, wherein the volume ratio of ethanol to deionized water can be selected as 2:1. Dissolving lipoic acid and polyethyleneimine (PEI) in a molar mass ratio of 1:1-1:3 in the mixed solvent, and adding a cross-linking accelerator ZnCl 2It is formed by magnetic stirring (lipoic acid and PEI are cross-linked through dynamic disulfide bonds (-SS-) and hydrogen bonds). In the self-healing material, the cross-linking accelerator ZnCl 2 The content is 0.1wt%-0.3wt%.

[0035] S4. A perovskite active layer is prepared on the dynamic self-repairing interface layer using a prefabricated perovskite active material, and the thickness of the perovskite active layer can be set to 400nm-600nm.

[0036] Furthermore, the preparation of the perovskite active layer includes: dissolving the perovskite precursor solution in a solvent configured with DMF and DMSO in a volume ratio of 4:1 to prepare the perovskite active material; coating the perovskite active material on the hole transport layer, vacuum flashing for a first preset time, and annealing for a second preset time under specific annealing conditions to form a 400-600nm dense perovskite film. Specifically, the corresponding coating process can be: coating gap 80-160μm, coating speed 10-50mm / s, vacuum flash time 60-180s; annealing conditions are 150°C annealing for 5-20min.

[0037] S5, stacking an electron transport layer (ETL), a hole blocking layer and a back electrode on the perovskite active layer. The electron transport layer (ETL) can be made of SnO 2 , PCBM or C60, and the thickness can be set to 30-80 nm; the hole blocking layer can be made of BCP or LiF, and the thickness can be set to 5-10nm; the back electrode is generally made of Ag, Au or Cu, and the thickness is 80-120nm.

[0038] Preparation of self-healing interface layer (DSIL): Preparation of precursor solution: Dissolve TA and PEI in a molar ratio of 1:1-1:3 in a mixed solvent of ethanol / deionized water (volume ratio 2:1) with a total concentration of 0.1-0.5 mg / mL; add 0.1wt%-0.3wt% ZnCl 2 As a cross-linking accelerator, it is fully dissolved by magnetic stirring. Coating process: slit coating, coating gap is 70~160μm, coating speed is 5-30mm / s, solvent evaporation time is 30-120s, annealing temperature is 80-120°C, annealing time is 5-20min.

[0039] Preparation of perovskite active layer: Dissolve the perovskite precursor solution in DMF:DMSO (4:1, v / v). Prepare by coating, with a coating gap of 80-160μm, a coating speed of 10-50 mm / s, and a vacuum flash time of 60-180 s; annealing conditions are annealing at 150°C for 5-20 min to form a dense perovskite film.

[0040] Self-repair verification thermal damage experiment: By controlling the annealing temperature and time, the dynamic disulfide bond recombination is triggered to achieve interface microcrack repair. The specific steps are as follows: the perovskite battery prepared according to the above embodiment (original state as Figure 2a The SEM image of the perovskite active layer (with the same thickness, between 400-600nm, preferably 550nm) after thermal stress damage is shown in Figure 1. Figure 2b As shown, the observation shows that the perovskite active layer has interface microcracks with a width of 100-300nm. After environmental aging, it was post-treated at 40℃ for 48h and the self-healing results were tested. Figure 2c-Figure 2e The following are SEM images of the self-healing results of the self-healing interface layers (with the same thickness, between 5-10 nm) corresponding to the molar mass ratio of lipoic acid (TA) to polyethyleneimine (PEI) in the self-healing material of 1:1, 1:2, and 1:3, respectively. Figure 2c-2e It can be seen that the perovskite battery provided in this application has good damage self-repair effect and interface passivation effect.

[0041] Correspondingly, Figure 3 The JV curve (short circuit current density (J)) of the perovskite battery module after the above 85°C thermal damage repair was obtained by testing the self-healing materials of lipoic acid (TA) and polyethyleneimine (PEI) in a molar mass ratio of 1:1, 1:2, and 1:3. sc ) and open circuit voltage (V oc ) relationship curve). Figure 3 As shown, the perovskite battery assembly (the effective area of ​​the experimental perovskite battery assembly is 63.76cm 2 The light intensity used is AM1.5G 100mW / cm 2 ) By comparing the efficiency before and after repair, it was found that the efficiency of the perovskite components after 40°C treatment had recovered to varying degrees. When the TA / PEI doping ratio was 1:2, the self-repair effect on the perovskite battery component was the best, and the corresponding photoelectric conversion efficiency increased from the initial 9.68% to 17.68% after damage, recovering to 97% of the original efficiency.

[0042] Figure 4The JV curves are obtained by testing the pre-prepared perovskite battery components with a dynamic self-repairing interface layer (the molar mass ratio of lipoic acid to polyethyleneimine (PEI) in the self-repairing material is 1:2) and without a dynamic self-repairing interface layer (the only difference is whether there is a dynamic self-repairing interface layer) in an 85°C constant temperature box for 24 hours to simulate thermal stress damage, and then post-treated at 40°C for 48 hours. Among them, the parameters of the perovskite battery component with a dynamic self-repairing interface layer are the same as those of the perovskite battery component used in the above self-repair verification thermal damage experiment.

[0043] Figure 5a , Figure 5b The pre-prepared perovskite battery components (the effective area of ​​the component is 63.76 cm 2 , light intensity is AM1.5G 100mW / cm 2 ) was placed in an 85°C thermostat for aging for 24 hours to simulate thermal stress damage (except that the molar mass ratio of the self-healing material lipoic acid to polyethyleneimine (PEI) was 1:2, the parameters of the pre-prepared perovskite battery component were the same as those of the perovskite battery component used in the above self-healing verification thermal damage experiment), and the JV curves were obtained by post-treatment at 40°C and 25°C, 40°C and 80°C for 48h. Figure 5a , Figure 5b It can be seen from the experimental results that the use of a post-processing temperature of about 40°C has a good effect on the thermal damage repair of the perovskite battery provided in this application.

[0044] The above description is only an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the technical solutions provided by the present application may be subject to various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A perovskite battery, characterized in that: A dynamic self-repairing interface layer is provided between the hole transport layer and the perovskite active layer of the perovskite battery, and the self-repairing material used in the dynamic self-repairing interface layer is formed by cross-linking lipoic acid and polyethyleneimine.

2. The perovskite battery according to claim 1, characterized in that The self-healing material is prepared by dissolving lipoic acid and polyethyleneimine in a mixed solvent of ethanol and deionized water at a molar mass ratio of 1:1-1:3, adding a cross-linking accelerator ZnCl2, and stirring.

3. The perovskite battery according to claim 2, characterized in that: The thickness of the dynamic self-repairing interface layer is 5-20 nm, and the thickness of the perovskite active layer is 400-600 nm.

4. A method for preparing a perovskite battery, characterized in that: The method comprises: sequentially stacking a hole transport layer, a dynamic self-repairing interface layer, a perovskite active layer and an electron transport layer on a conductive substrate; the self-repairing material used in the dynamic self-repairing interface layer is obtained by cross-linking lipoic acid and polyethyleneimine.

5. The method according to claim 4, characterized in that The method comprises: mixing lipoic acid and polyethyleneimine in a molar mass ratio of 1:1-1:3, dissolving the mixture in a mixed solvent of ethanol and deionized water, and adding a cross-linking accelerator ZnCl2 and stirring to prepare the self-healing material.

6. The method according to claim 5, characterized in that The total concentration of the mixed solvent is 0.1-0.5 mg / mL, the volume ratio of ethanol to deionized water is 2:1, and the content of the cross-linking accelerator ZnCl2 is 0.1-0.3 wt%.

7. The method according to any one of claims 4 to 6, characterized in that The method comprises: coating the self-repairing material on the hole transport layer through a slit, volatilizing and annealing to form the dynamic self-repairing interface layer with a thickness of 5-20 nm.

8. The method according to claim 7, characterized in that The conductive substrate is set as a transparent conductive glass or a flexible PET substrate, and the hole transport layer is set as a NiO layer with a thickness of 20-50 nm. x , PEDOT:PSS or Spiro-OMeTAD.

9. The method according to claim 7, characterized in that The preparation of the perovskite active layer includes: dissolving a perovskite precursor solution in a solvent prepared by DMF and DMSO in a volume ratio of 4:1 to prepare a perovskite active material; coating the perovskite active material on the hole transport layer, vacuum flash evaporating for a first preset time, and annealing for a second preset time under certain annealing conditions to form a 400-600nm dense perovskite film.

10. The method according to claim 4, characterized in that The method further comprises: sequentially stacking a hole blocking layer and a back electrode on the perovskite active layer.

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