Study On Surface Modification And Interfacial Electronic Structure Of Organic-Inorganic Hybrid Perovskite Film

Organic-inorganic hybrid perovskite thin films have the excellent properties such as high absorption coefficient,adjustable band gap and long carrier diffusion length,which is widely used in perovskite solar cells、photodetectors and field-effect transistors.In order to effectively restrain the non-radiative recombination in perovskite films,the device performance of perovskite solar cells is improved by surface modification of perovskite films.In this paper,the surface properties of organic-inorganic hybrid perovskite films and the interface electronic structure between perovskite thin films and ferromagnetic electrode Co were systematically studied by using surface analysis techniques such as X-ray photoelectron spectroscopy（XPS）、ultraviolet photoelectron spectroscopy（UPS）、atomic force microscopy（AFM）and X-ray diffraction（XRD）.The specific research contents are as follows:（1）The effect of chemical additive NH₂-POSS on the electronic structure、surface composition and surface morphology of organic-inorganic hybrid perovskite films were studied.The surface composition and element distribution of perovskite films can be regulated by changing the concentration of NH₂-POSS,it is found that too high concentration of NH₂-POSS will destroy the morphology of perovskite films,and appropriate concentration of NH₂-POSS can effectively improve the quality of perovskite films and improve the performance of devices.The effects of the interaction between M（ACAC）_n and organic-inorganic hybrid perovskite thin films on the surface electronic structure and surface components of perovskite film was studied,it is found that the charge transfer between V（ACAC）₃、Cu（ACAC）₂、ACAC and perovskite film was 0,15 e V,and there was obvious chemical reaction between Sn（ACAC）₂ and perovskite film,which affects the chemical composition and element distribution of perovskite film.（2）The evolution of the interface electronic structure of MAPb Br₃/Co interface with the thickness of Co film was studied by XPS and UPS.The results show that during the whole process of Co deposition,obvious chemical action takes place at the interface and new compounds are formed;there is a p-type doping characteristic at the MAPb Br₃/Co interface,which will disappear when the Co film is thick enough;there is an interface dipole of 0.12 e V at the MAPb Br₃/Co interface.