Fused-ring Electron Acceptor:A Novel Solution For Interfacial Modification Of Perovskite Solar Cells

Perovskite solar cells(PSCs)have attracted extensive attention from scientists in the field of photovoltaics due to their high,power conversion efficiency(PCE),low cost,and easy large-area manufacturing.Among them,The rational interface design of oxide electron transport layer and modification is an effective method to improve the photovoltaic performance and the long-term stability of PSCs.Therefore,this paper discusses and solves the scientific problems of perovskite material in the PSCs application process through the structural design optimization of the interface of perovskite/electron transport layer,and clarifies the PCE and working long-term of specific components and functions of PSCs in the interface structure.The effect of stability and the microscopic mechanism of device degradation suppression.The main research contents and results aresummarized as follows:1.The non-fullerene electron acceptor material ITIC-Th containing alkyl thiophene side chain modified TiO2 electron transport layer was used to prepare high performance and stable planar junction PSCs.The research shows that the interfacial modification by ITIC-Th improves the morphology,contact angle and other properties of TiO2 film,enhancethe growth of perovskite crystals,which is beneficial to the extraction,transport and collection of photo-generated carriers,and finallygreatly reduces the surface recombination of charge carriers.Consequently,the PCE of TiO2/ITIC-Th based PSCs increased from 15.43%to 18.91%.The device stability of inorganic-organic hybrid PSCs was also investigated.When placed at room temperature and relative humidity of 30%for about 1000 hours,the tested PCE of ITIC-Th based PSCs remained at 90%,which was significantly higher than that of pure TiO2-based PSCs under the same conditions.The test results shows a very good prospect of ITIC-Th for performance improvement by interfacial modification in PSC.2.Another non-fullerene electron acceptor material ITIC containing alkyl thiophene side chain modified TiO2 electron transport layer was also used to prepare high performance and stable planar junction PSCs.According to the research,the interfacial modification of ITIC improves the surface flatness,enhances the crystal quality of the perovskite,and reduces the resistivity and charge recombination loss,thereby improving the overall performance of the PSCs.Ahigh efficiency of 19.61%was obtained,based on the TiO2/YTIC ETL rigid PSCs.The efficiency was increased by 15.4%,and the hysteresis decreased by 58.7%than the control cell(PCE 16.99%).Especially for flexible devices,ITIC-modified PSCs have greatly improved their device stability in air.After being placed at room temperature and relative humidity of 30%for about 500 hours the PCE still maintained at 80%,which was significantly higher than that of pure TiO2-based PSCs.This research will further promote the commercialization of high-efficiency flexible PSCs.