Preparation And Performance Of Photodetectors Based On Perovskite Microwires

In recent years,with the continuous progresses of science and technology,high-performance photodetectors have been widely used in optical communication,space exploration,military,and other fields.However,photodetectors based on traditional silicon-based materials,or other three-dimensional semiconductor devices are usually fabricated on a rigid sink,which are fragile,expensive,and complex in manufacturing processes,making it difficult to be designed for new flexible photodetectors.Due to the well development of the excellent lead halide perovskite materials and the preparation of low dimensional device structures with excellent mechanical flexibility,now it is considered as a powerful candidate for the preparation of high-performance transparent flexible photodetectors.However,the shortcomings of lead halide perovskite materials were easy degradation and poor stability.And the photoelectric properties of lead halide perovskite materials also showed the great differences due to the preparation methods.In this thesis,we chose one crystallization methods to prepare CH₃NH₃PbI₃ perovskite microwires,and characterized them by Raman spectrum and Raman mapping.Then,CH₃NH₃PbI₃ perovskite microwires were invented and designed as photoconductive detectors.And their photoelectric properties were tested by semiconductor parameter analyzer and laser with different wavelengths and powers.The experimental results show that CH₃NH₃PbI₃ perovskite microwires prepared by fluid-guided antisolvent vapor-assisted crystallization(FGAVC)have better crystallinity and less degradation on the surface.As a contrast,the CH₃NH₃PbI₃ perovskite microwires prepared in nitrogen environment were aggregated and degraded more easily.In this thesis,by obtaining Raman spectra and laser surface treatment,it is confirmed that PbI₂ were accumulated on the surface of CH₃NH₃PbI₃ perovskite microwires when they are degraded.It is demonstrated in detail that when PbI₂ exists,an obvious Raman peak showed nearby 97 cm^-1,and the intensity of Raman peaks at 105 cm^-1 significantly enhanced.Finally,we propose a method to improve the photoelectric performance of CH₃NH₃PbI₃microwires by laser surface treatment with high power laser,which is proved by Raman mapping and photoelectric performance data.