Organic-inorganic hybrid halide perovskite has been widely used in various optoelectronic devices due to its low production cost,simple process flow and excellent optoelectronic performance.However,its poor stability and Pb2+toxicity are not conducive to large-scale practical applications.Replacing lead with non-toxic elements can solve such problems,for example,Cs3Bi2I9has the advantages of non-toxic and high stability.so it has attracted more and more attention.However,due to its zero dimensional structure(0D)containing discrete[Bi2I9]3-clusters,Cs3Bi2I9has structural defects that increase the recombination probability of photo-generated carriers,thereby limiting the charge transport characteristics.Therefore,this work adjusts the structure and dimension of Cs3Bi2I9single crystal through the strategy of halogen doping,thereby improving the performance of Cs3Bi2I9single crystal photodetector.The research content of this article is as follows:1.Br doped Cs3Bi2I9single crystals were synthesized by reverse temperature crystallization method,achieving a transformation of the structure of Cs3Bi2I9single crystal from 0D to 2D.The absorption edge of the single crystals blue shifted,the optical band gap increased from 1.87 e V to 2.00 e V,and the photoluminescence intensity was also enhanced.In addition,the incorporation of Br can reduce the density of trapped states in Cs3Bi2I9single crystal.Among a series of prepared single crystals,Cs3Bi2I6Br3single crystal has a high crystallinity,an optical band gap of 1.95 e V,and a minimum trap state density of 1.28×1010cm-3.At the same time,the carrier mobility of the single crystal significantly increased from 273 cm2V-1s-1to 772 cm2V-1s-1.2.A metal semiconductor metal planar photodetectors were prepared based on Br doped Cs3Bi2I9single crystals.Among them,the photodetector(Au/Cs3Bi2I6Br3/Au)prepared based on Cs3Bi2I6Br3single crystal has the best performance.The device has a spectral response of 31 m A/W at an external bias of 10 V.The I-t test shows that the photocurrent of the device remains almost unchanged during 10 repeated cycles without significant attenuation,indicating that the photodetector prepared based on Cs3Bi2I6Br3single crystal has good cycle stability.In addition,the response time test shows that the the device of rise time is 40μs,fall time is 370μs,Proving it has fast response to optical signals. |