Construction And Performance Control Of SnO₂ Nanofibers And Bi-based Perovskite Thin Film Ultraviolet Photodetectors

In recent years,people's demand for various kinds of high-performance electronic devices is increasing with the rapid development of industry and society.Among them,ultraviolet photodetectors are a necessary optoelectronic device,and applied widely in in civilian and military areas,such as biological effects,environmental monitoring,aerospace communications,flame detection,missile warning and water purification,etc.Although traditional ultraviolet photodetectors have developed rapidly,there are still some problems.For example,the volume of the first-generation ultraviolet photomultiplier tubes is so large that it is difficult to carry.In addition,traditional silicon-based photodetectors have a narrow band gap,so they need to be equipped with expensive filters.In order to meet people's growing production and living needs,it is imperative to develop competitive traditional wide band gap oxide semiconductor materials and develop new perovskite materials applied in ultraviolet photodetectors.Therefore,in this thesis the following two works have been studied systematically:?1?High quality and controllable photodetectors based on the 1D SnO₂ nanomaterials prepared by electrospinning technique.Based on the repeated experiments and theoretical analysis,the relationship between process parameters and photoelectric properties was established,and the morphology including nanofiber and nanotube of 1D SnO₂nanomaterials was controlled by adjusting the Sn amount in precursor solution.Among them,the best field effect transistor based on 0.2 SnO₂?0.2 g SnCl₂·4H₂O added in the precursor solution?nanotubes has an on-off current close to 10^-4A and a switching current ratio of 2.4x10⁶.The ultraviolet photodetector using 0.2 SnO₂ nanotubes as channel materials also exhibit an excellent ultraviolet photo detectivity,which has a strong response to UVB.Under the ultraviolet irradiation of 280 nm,the sensitivity,responsivity and detection rate of the 0.2 SnO₂ nanotubes are up to 2003,214 AW^-1 and 2.19x10¹³ Jones,respectively.Finally,the substrate of the photodetector based on 0.2 SnO₂ nanotubes is replaced by FTO glass,and a transparent UV photodetector is constructed.This transparent UV photodetector achieved a sensitivity of about 200,and the visible transmittance is over85%.?2?The development of new materials is also one of the future development directions of ultraviolet photodetectors.Perovskite material has become a potential candidate material for high-performance photodetectors due to its excellent photoelectric properties.Considering the advantages of Bi based perovskite such as low cost,stable physical and chemical properties and non-toxicity,a series of Cs₃Bi₂I_9-xBr_x?x=0-9?perovskite films were prepared by a simple spin-coating method.SEM was used in characterizing the morphology of the Cs₃Bi₂I_9-xBr_x?x=3-9?.Seven kinds of compact and flat thin films of Cs₃Bi₂I_9-xBr_x?x=3-9?were selected to construct photodetectors and their photoelectric properties were systematically studied.All inorganic Bi based perovskite photodetector with high photosensitivity and fast response time.Among them,the photodetector based on Cs₃Bi₂I₆Br₃ films exhibits high response to UV light,and its photosensitivity and detectivity reach 41000 and 4.6x10¹¹ Jones,respectively.Meanwhile,the response time and recovery time are only 40.7 and 27.1ms.In addition,the Bi based photodetector has excellent stability at room temperature,and its photocurrent can maintain stable for 100days without obvious attenuation.