Preparation And Properties Of Photodetectoes Based On CsPbBr₃ Single Crystal

In recent years,halide perovskite materials have become a hotspot semiconductor material in the field of optoelectronic research due to their high optical absorption coefficient and superior carrier mobility.However,organic-inorganic hybrid perovskites are easily affected by factors such as water vapor,temperature,and irradiation,making them easy to decompose,which restricts their wide application.All-inorganic perovskites have good stability while ensuring good optoelectronic properties,so they have received extensive attention in the field of photodetection.With the continuous development of science and technology,the demand for high-performance photodetectors is increasing.At present,most photodetectors based on perovskite materials use polycrystalline films as light absorption layers,but polycrystalline films have a large number of grain boundaries and defects,which affect the transport effect of carriers.While perovskite single crystals have no grain boundaries and have lower charge trap density,longer carrier lifetime and higher stability than polycrystalline films,they have become a fundamental research platform and the key to optimizing detector performance.The research work of this thesis focuses on the preparation of all-inorganic CsPbBr₃perovskite single crystals and their photodetector properties.The main work is as follows:1、Preparation and Properties of Photodetectors Based on All Inorganic Perovskite CsPbBr₃Bulk Single Crystals.On the basis of the traditional inversion temperature crystallization,a two-stage heating crystallization method is used to grow high-quality CsPbBr₃bulk single crystals by slowly evaporating the solvent and controlling the nucleation at lower temperature and crystallization at higher temperature.Construction of metal-semiconductor-metal type photodetectors based on high-quality CsPbBr₃bulk single crystals.The I-V curves of the photodetectors were tested under dark conditions and light.Under 3 V bias,the light-dark current ratio is 634.We tested the spectral response characteristics of the photodetector with a maximum responsivity of 0.15 A W^-1at 550 nm,under 7 V bias.At the same time,the device has a fast response speed with rise/fall times of 8.3/684.9μs,respectively.2、Preparation and properties of self-driven photodetectors based on all-inorganic perovskite CsPbBr₃thin single crystals.Due to the large size of the bulk single crystal,it does not meet the development needs of device miniaturization.Therefore,the experimental method was further improved.The CsPbBr₃perovskite thin single crystal was grown by introducing the space confinement method based on the two-stage heating method.Finally,based on the thin single crystal,a self-driven working characteristic of the photodetector is realized by constructing an asymmetric electrode（Au-Ag）.Under illumination,the I-V curve of this detector exhibits obvious rectification characteristics with an open-circuit voltage of0.73 V.The obvious photovoltaic effect enables our device to operate at 0 V bias voltage.The responsivity can reach 27 m A W^-1at 530 nm,under 0 V bias.meanwhile,the device with asymmetric electrode pair exhibits fast response speed with rise/fall times of 3.93/123.56μs,respectively.