Research On Photodetector With The Structure Of Phototransistor Base On Inorganic Perovskite Thin Film

All-inorganic halide perovskites(AIHPs)have attracted enormous attention due to their inherent high optical absorption coefficient and superior environmental stability.However,the research on visible-blind ultraviolet(UV)detectors are still seldom reported.This thesis studies the high-performance UV detectors based on solution processed AIHPs thin film materials,mainly.The specific method of preparation of the thin film which was determined by comparing various AIHPs film deposition technique was firstly discussed.Then a phototransistor detector based on the AIHPs thin film was fabricated,and the cut-off wavelength of detection was shifted to the UV band by adjusting the composition of the halogen element,which lay a the foundation for the realization of visible-blind ultraviolet detectors.The details are discussed as follows.1.The preparing process of the CsPbBr₃ film has been optimized.Firstly,for preparing CsPbBr₃ polycrystalline thin films,several solution processed methods were investigated and optimized.As a result,the multi-step deposition technique was finally adopted.To ensure the high quality of the film,the prepared film's performance of crystallinity,microscopic morphology and defect density were characterized.And the analysis of optical properties shows that the CsPbBr₃ film has a direct band gap of 2.36 e V,which meets the needs of ultraviolet-visible detectors.2.The photodetector,in which the CsPbBr₃ film plays as an active layer,was prepared by combining the thin film with the transistor structure.In order to improve the performance of photodetector further,the CsPbBr₃ film was combined with the amorphous indium gallium zinc oxide(IGZO)film,we designed the hybrid active layer phototransistor and extracted photogenerated carriers from Cs Pb Br3 using IGZO layer to achieve high detectivity and fast responsivity.As a consequence,the obtained device exhibits outstanding performance on the on/off ratio(3.2×10⁴),the responsivity(10.7A/W)and the detectivity(1.8×10¹³ Jones).More importantly,the device shows a fast responsivity of 4.9ms/15ms and a wide linear dynamic range of 123 d B.3.The cut-off edge of detection was blue-shifted to the UV range through compositional modulations of the halogen element of the inorganic perovskite.The Cs Pb Cl₃ film was prepared by multi-step spin-coating and the preparation process was optimized.Afterwards,a Cs Pb Cl₃film with good compactness and high crystallinity was obtained.What is more,this Cs Pb Cl₃film owns a band gap of 2.91e V,and the absorption cut-off wavelength of the AIHPs film was blue-shifted to the UV region.4.Based on the high-performance phototransistor with CsPbBr₃/IGZO hybrid active layer,the preparation and performance optimization of the phototransistor detectors based on the Cs Pb Cl₃ thin film were obtained.We first fabricate a phototransistor with the Cs Pb Cl₃ film as the active layer.After that,a visible-blind ultraviolet photodetector was obtained.The Cs Pb Cl₃film was further combined with the IGZO-TFT to construct ultraviolet phototransistor with an IGZO/Cs Pb Cl₃ hybrid channel layer.As a consequence,the obtained device exhibits the on/off ratio of 520,the responsivity of 0.43A/W and the detectivity of 6.4×10¹¹ Jones at a wavelength of 350 nm,and a fast response speed of 7.1ms/7.0ms was achieved at the same time.In this thesis,high-performance UV detectors based on solution processed AIHPs thin film materials are fabricated,which lays a foundation for the research of visible-blind ultraviolet photodetectors.