Research On High-Performance And Stable Photodetector Based On Organic-Inorganic Hybrid Perovskite

Perovskite material has the advantages of high light absorption coefficient,high carrier mobility,long carrier diffusion length and adjustable band gap,as well as low preparation cost and easy integration with flexible platform,making it one of the ideal materials for preparing high-performance photodetectors.However,perovskite photodetectors（PPDs）still face three main problems:low performance,poor stability and narrow spectral response range.This dissertation mainly focuses on these three problems,and improves them to a certain extent through the introduction of new materials,new structures and new mechanisms.The main research contents are as follows:1.High-performance PPDs were prepared by a one-step method through the assistance of antisolvents.By studying the effect of antisolvent polarity on MAI·PbI₂·DMSO mesophase,it is determined that the antisolvent with moderate polarity is more conducive to improving the quality of perovskite film and enhancing the performance of PPD.Meanwhile,two antisolvents SPA and TAA with moderate polarity were introduced to prepare high-performance perovskite films and TAA was proposed and reported for the first time.As a result,the performance of these two devices was significantly improved.2.High-performance and stable 2D/3D stacked PPDs were prepared by introducing new 2D materials BAAc and PEAAc,of which PEAAc was first proposed by us.Through the interaction between Lewis base functional groups in BAAc and PEAAc and Lewis acid Pb⁺,the crystal defects of perovskite can be effectively passivated and the film quality can be significantly improved.At the same time,the hydrophobic terminals formed by BA⁺and PEA⁺can not only inhibit the penetration of water molecules and enhance the humidity stability of the film,but also improve the temperature stability of the film by inhibiting the cross-layer migration of ions.As a result,the responsivities of the devices reach 2.11 A W^-1 and 2.32 A W^-1 under 532 nm laser irradiation,respectively.At the same time,the nonencapsulated devices retained high initial performance after exposure to ambient air for 20 days.In addition,we have successfully integrated our PPDs into the visible light communication system to achieve fast text and audio signal transmission.3.A hybrid photodetector with wide spectral detection capability was prepared by combining MAPbI₃ perovskite with organic bulk heterojunction（OBHJ）.With the participation of OBHJ layer,the response spectrum of PPD has been successfully extended to the near-infrared band.Moreover,due to the effective passivation of defects on the perovskite surface and grain boundaries by OBHJ layer,the morphology of perovskite film is significantly improved,thus greatly improving the moisture stability of the device.