Preparation Of Perovskite Based On Halogen Regulation And Application Of Photodetectors

Inorganic semiconductor materials,such as GaN-,Si-,and InGaAs-,are the most common components for UV photodetector.However,these inorganic materials are often synthesized by complex or expensive approaches.Organic-inorganic lead halide perovskite materials with enormous families have attracted the extensive attention within these years.Perovskite solar cells show a power conversion efficiency?PCE?more than 24%.In particular,hybrid perovskite film show high absorbance in the visible light of 400nm-800nm.Therefore,perovskite materials are ideal candidate for the development of visible light detectors.The doping of Cl element in the MAPbI₃ perovskite materials can effectively improve the grain size of perovskite film,modify the band gap of perovskite material,cause a slight blue shift of the absorption spectrum,increase the ultraviolet absorption,and thus affect the performance of the photodetector based on perovskite material.This paper studies the effect of Cl element doping on the properties of perovskite films and the application of Cl dooped MAPbI₃ in perovskite photodetectors and flexible perovskite photodetectors,focusing on the preparation of 10%PbCl₂-MAPbI_3-xCl_x films and its applications in normal and flexible devices.The specific research is summarized as follows:?1?A portion of PbI₂ was replaced by adding PbCl₂ to the precursor solution of MAPbI₃ perovskite material to prepare a MAPbI_3-xCl_x perovskite film.The effects of different Cl doping ratios on the film were compared by SEM,UV-Vis absorption spectroscopy and XRD.According to the results,10%PbCl₂ was the most suitable doping ratio.This suitable ratio can increase the grain size of the perovskite film,reduce the defect recombination probability,and increase the band gap for the film,cause blue shift of the light absorption.?2?In this paper,photodetector based on Cl-doped perovskite material was prepared by an optimized one-step solution method.It can be seen from the I-t curve that the 10%PbCl₂-doped perovskite film has high sensitivity to both ultraviolet and visible light,and a high photocurrent value can be obtained under an applied bias of less than 0.3V.Meanwhile,different optical signal intensity have limited influence on the photocurrent of photodetector.As exhibited by the transient photocurrent curve,the response speed of the photodetector is in the microsecond range and the rise time or decay time is less than 90?s.As can be seen from the I-V curve,it can be concluded that the photodetector has an on/off ratio of about 10³,and its responsivity is about 0.05 A/W,which is relatively high under weak optical signal,and the detectivity of the device for the 405 nm light signal is up to 10¹¹ Jones.?3?A flexible photodetector based on 10%PbCl₂-MAPbI_3-xCl_x was prepared.The device was bent to different degrees,and its performance was less affected.After repeated bending of different times,the photocurrent was hardly affected,which proved that the device has good mechanical stability and was less affected by the external bending force.