Preparation And Optoelectronic Properties Of CsPbBr₃ Thin Films Deposited By Pulsed-laser Deposition

Recently,metal halide perovskite due to remarkable characteristics,including high light absorption coefficient and carrier mobility,low defect density of states,tun-able emission wavelength and longer carrier diffusion distance has become a“super-star”in the field of semiconductor optoelectronic material.Its research fielded extendsfrom solar cells to various photoelectric devices,such as photodetectors?PD?,light-emitting diodes?LED?,lasers?LD?,And has made breakthrough progress.At present,organic-inorganic hybrid perovskite and all-inorganic perovskite are mainly prepared by solution method,which is prone to structural defects and non-uniform thin films.It has been become a bottleneck for their application of photoelectric devices.In this paper,pulsed laser deposition?PLD?technology is used to prepare an all-inorganic perovskite films.PLD technology is a vacuum vapor deposition method,which can effectively reduce the defect density of the material by accurately adjusting growth pa-rameters,such as growth temperature and laser frequency,realize the controllable growth of high-quality CsPbBr₃ perovskite thin film materials.On this basis,the ap-plication of CsPbBr₃ perovskite thin films in photodetectors,light conversion devices,light emitting diodes and other photoelectric devices was studied.This study not only provides theoretical basis and technical support for the vacuum preparation of high-quality perovskite thin films,but also provides a feasible technical approach for the application of perovskite photoelectric devices.The mains contents of this article as the follows:1.Growth of high quality CsPbBr₃ films by pulsed laser deposition.CsPbBr₃films have been prepared by PLD technique,the effects of the target materials com-position ratio?CsBr/PbBr₂?and substrate temperature on the morphology,structure and photoluminescence properties of CsPbBr₃ thin films were characterized through X-ray Energy Dispersive Spectrometer?EDS?,X-ray diffraction?XRD?,and photolumines-cence?PL?.The results show that when CsBr/PbBr₂ is 1:1,the prepared film behaves as a monoclinic CsPbBr₃ material,and without CsPb₂Br₅,Cs₄PbBr₆ and other compo-nents.In addition,the substrate temperature has a greater impact on the crystal quality of CsPbBr₃ film,When the substrate temperature is 150°C,the CsPbBr₃ film has the best crystal quality.2.CsPbBr₃/n-Si heterojunction photodetector.CsPbBr₃ thin films have been pre-pared on n-Si the surface of n-Si substrate by PLD and the performances of the CsP-bBr₃/n-Si heterojunction devices were characterized.The CsPbBr₃/n-Si heterojunction photodetector exhibits diode-like rectifying behavior,and the photocur-rent-to-dark-current ratio and peak responsivity of the heterojunction are approximate-ly 168.5 times and 0.6A/W?-5V,520nm?,respectively.Furthermore,the CsPbBr₃/n-Si heterojunction photodetectors exhibits fast response and recovery times.3.Preparation of all inorganic perovskite CsPbBr₃ micron-thick film and its ap-plication for light conversion devices.The all inorganic perovskite CsPbBr₃ mi-cron-thick film has been successfully prepared by pulsed laser deposition technology,and the CsPbBr₃ thick film composed of columnar crystals with the preferential crystal direction of?100?was obtained,and the film thickness was effectively controlled by setting the number of pulsed laser.A few of decay is observed when the CsPbBr₃ mi-cron-thick films are tested after 18 days of exposure to ambient environment.In addi-tion,when the thickness of CsPbBr₃ film is 2.252?m,a pure and effective green light emission is achieved under the excitation of blue light?460 nm?.4.Effect of CsPbBr₃ on the photoelectric properties of n-ZnO/p-GaN heterojunc-tion.Based on the unique band gap and carrier transmission characteristics of CsPbBr₃material,the carrier transport performance of ZnO/GaN heterojunction can be effec-tively adjusted.We used pulsed laser deposition technology to prepare CsPbBr₃ thin film as the interface layer at the ZnO/GaN heterojunction.It can be found that the ZnO/CsPbBr₃/GaN heterojunction photodetectors can realize UV detection at 365nm at0V bias voltage.And the peak responsivity and detectivity of the ZnO/CsPbBr₃/GaN heterojunction are 44.53mA/W and 2.03?10¹²Jones,respectively.Compared to ZnO/GaN heterojunction device have increased?30 and?178 times.In addition,the CsPbBr₃ interface layer has a significant adjustment effect on the electroluminescence of the ZnO/GaN heterojunction.Under forward bias,the ZnO/CsPbBr₃/GaN hetero-junction LED exhibits a dominant wide band emission from 450 to 80a0nm,and a tunable electroluminescence spectrum is achieved by precisely controlling the thick-ness of the intermediate layer.