Research On Electron Transport Layer And Its Interface Regulation To Construct Perovskite Solar Cells

Organic inorganic halide perovskite solar cells（PSCs）are considered as the most potential technology in the field of photovoltaic due to their excellent photoelectric performance,simple preparation method and low cost.In the past decade,the photoelectric conversion efficiency of PSCs has soared.The current certification efficiency has reached 25.5%,but it has not yet reached its theoretical limit.There is still room for development.In the PSCs,the qualities of electrode,electron transport layer（ETL）light absorption layer,hole transport layer（HTL）and the interface between the films are very significant to improve the performance of the device,so the research on the films and interfaces of the device is of great significance.In this thesis,efficiency and stability of the ETL and its interface are mainly studild,and the photoelectric performance and environmental stability of PSCs through interface engineering are improved.The main research contents are as follows:（1）SnO2 thin films prepared by magnetron sputtering were inserted into the interface between FTO anode and TiO2 ETL,and the PSCs with excellent performance were obtained.When 6 nm thick SnO2 film was inserted,the surface of FTO electrode was smoother,the energy level difference between FTO and TiO2 was reduced,the energy band of the device was adjusted,the collection and extraction of electrons were promoted,and the interface charge recombination was reduced.Simultaneously,the surface of subsequent TiO2 films was smoother and the bulk and surface defect density of the films were reduced.Furthermore,the double-layer ETLs structure improved the interface quality of TiO2/perovskite,promoted the growth of perovskite grains and improved the carrier extraction efficiency.Compared with single-layer TiO2 based cell,the device with SnO2/TiO2 ETLs can yield an efficiency as high as 21.45%,and it still keeps good environmental stability after 40 days.（2）The optical and electrical properties of PSCs were optimized by introducing RbBr into the interface between TiO2 and perovskite.The analysis shows that the RbBr interface modification has a multi-functional effect of interface optimization.For the TiO2 layer,the surface roughness decreases and the energy levels match better after the introduction of RbBr,which significantly promotes the electron extraction.Moreover,the perovskite film has smooth surface,less grain boundaries,good hydrophobicity and lower defect density.More importantly,the efficiency of PSCs modified with 5 mg/ml RbBr can reach 21.15%,and the air stability test indicates that the device can still maintain 90%of the original efficiency after 500 h.（3）RbCl was introduced into TiO2 thin films by low temperature water bath method to prepare excellent ETL.It is found that the defect density of the modified TiO2 film was decreased,which improved the ability of electron transportation and extraction,and indirectly ameliorates the quality of the perovskite film.Compared with the control TiO2 film,the surface roughness of doped TiO2 film was reduced,the hydrophilicity was improved,and the conductivity was increased.In addition,when the doping concentration of RbCl was 10%,the optimum efficiency of the device is significantly improved to 21.82%,and the corresponding photovoltaic parameters were also enhanced.These results indicate that element doping is an effective method to modify ETLs for preparing high-performance planar heterojunction PSCs.