| Photovoltaic power generation can directly convert solar energy into electricity and serve human production and life,becoming an important new energy technology.At present,photovoltaic power generation is mainly based on silicon-based solar cells,but it faces practical problems such as difficulty in reducing costs and increasing efficiency,limited raw material reserves,and complex processes.Perovskite material has the characteristics of rich source,low cost,solution processing and excellent photoelectric properties.It is a very suitable photoelectric material for solar cells.Perovskite solar cells(PSCs)have received extensive attention.In the preparation of perovskite films,the use of high-temperature rapid crystallization film preparation technology will produce a large number of defects at the grain boundaries and interfaces of perovskite films,resulting in non-radiative recombination and affecting the transport of carriers.This not only affets the performance of the device,but also affects its industrialization process.Additive engineering and interface engineering are the most simple and effective methods to improve device performance.Therefore,it is necessary to explore effective additive engineering and interface engineering materials and processes to further explain the mechanism of action.In this paper,the PSCs with carbon electrode and no hole transport layer structure are studied.It is proposed to use potassium KPF6 to passivate the defects of perovskite grain boundaries and interfaces,so as to improve the crystal quality of perovskite films and optimize the interface energy level matching of cells.The photoelectric properties and stability of all-inorganic CsPbBr3 PSCs have been greatly improved.The main research work is as follows:(1)Aiming at the defects of perovskite grain boundaries,KPF6 was proposed to passivate the grain boundaries of CsPbBr3 perovskite absorption layer film,which effectively improved the photoelectric conversion efficiency of FEO/c-TiO2/CsPbBr3/carbon PSCs.In the experiment.different concentrations of KPF6 were added to the precursor solution of perovskite.It was found that the PC E of the device increased from 8.24%to 10.02%when the concentration of KPF6 was 1%.The reason for the improvement of device performance is that the additive KPF6 can coordinate with the under-coordinated Pb2+ and Br-to make the perovskite crystal structure more complete,which is conducive to charge transport.At the same time,it was found that the average size of perovskite grains increased from 0.94 μm to 1.13 after 1%KPF6 treatment,which also promoted the growth of film grains.The results show that the introduction of perovskite precursor solution KPF6 realizes the passivation of perovskite grain boundaries,the reduction of film roughness and the improvement of device performance.(2)Aiming at the problem of energy level mismatch at the interface,KPF6 was used to modify the TiO2/CsPbBr3 interface to prepare PSCs with KPF6 modified perovskite interface layer.It was found that the PCE of the device increased from 8.06%to 9.84%when the KPF6 concentration was 2%.The mechanism of KPF6 improving device efficiency is further studied.The first aspect is to obtain high-quality perovskite films by regulating the growth process of the films.The second aspect is to make the energy levels between the electron transport layer and the perovskite layer more matched by modifying the interface,and the non-radiative recombination of carriers at the interface is suppressed,so that the carriers can be transported quickly and highefficiency perovskite devices can be realized. |
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