Preparation And Photoelectric Detection Of Low Dimensional All-inorganic Perovskite CsPbBr₃

As a new type of optical detector,perovskite photodetectors have the broad application in the fields of imaging,optical communication,remote control and biological sensing.In this regard,aimming at the instability of organic perovskite polycrystalline materials to light,heat and oxygen,as well as the high dark current of its photodetector,this paper proposes to construct an all-inorganic CsPbBr₃ single crystal materials to study its light and electrical properties and stability.All-inorganic CsPbBr₃ photodetector with schottky barrier were developed,and their light detection performance was systematically studied.Besides,the flexible large-area array photodetectors were prepared by directly sprayed-processable method.The main research contents and innovation are as follows:?1?Based on the characteristics of low solubility,easy nucleation and selective growth of lead iodide?PbI₂?in N,N-dimethylformamide,we successfully prepared PbI₂ microwires.Then self-assembled CsPbBr₃ microwires were prepared by anion exchange method with PbI₂m wire as the template.The single CsPbBr₃ microwire photodetector shows ultra-low dark current of 2.1×10^-12 A in dark.This is attributed to the formation of a schottky barrier between the micron wire and the electrode,which effectively prevents carrier transport in dark.Under the illumination of 450 nm,the on/off ratio is as high as 10⁴,and the responsivity is 2500 mA W^-1.Further,after 4 hours of continuous illumination,the photoelectric performance of devices remains stable,and the devices show high degree of stability.What's more,the single CsPbBr₃ microwire photodetectors can accurately interpret the coding sequence,which demonstrates that the as-prepared photodetector has a potential application in optical communication.?2?In order to solve the problem of high trap density and low carrier transport efficiency in polycrystalline CsPbBr₃ materials,we prepared the CsPbBr₃ micro-crystalline film with low trap density and controllable thickness by inverse solvent method.Even at zero bias,the response time of the CsPbBr₃ microcrystalline thin film photodetectors is as fast as 51 ms,and the responsivity is 233.6 mA W^-1,demonstrating the unique self-powered characteristics of the devices.Under external bias,the as-prepared photodetectors exhibit ultra-fast response speed of 0.14 ms,responsivity as high as 5692 mA W^-1,comparable detectivity of 4.9×10¹²Jones and excellent external quantum efficiency of 2.5×10³%.More importantly,the photocurrent of the device has a linear relationship with the illumination power,showing a wide linear dynamic range?65.6 dB?.?3?A new method for fabricating large-area array flexible photodetectors by full sprayed-processable method is presented in this paper.The active materials and electrode materials are ultra-thin CsPbBr₃ single crystal nano-sheet and two-dimensional layered Ti₃C₂T_x with high conductivity,respectively.By adjusting the thickness and interelectrode spacing of Ti₃C₂T_x electrode,it can not only achieve short carrier transmission distance,but also effectively improve the carrier collection efficiency.The on/off ratio of as-prepared photodetectors is up to 2.3×10³,and the optical response time is 18 ms.Moreover,under a bias voltage of 10 V,the detectivity of the devices is 6.4×10⁸ Jones,and the responsiveness is as high as 44.9 mA W^-1.Moreover,after continuous bending 1500 times and storing for 3 months in the atmospherethe,performance retention rate of devices are still as high as 85 and 80%,respectively.In addition,the photodetectors can be integrated in large-area array,which provides a good reference for the practical application of image sensing.