Synthesis And Optoelectric Properties Of Copper-based Halide Perovskite

Due to their excellent optoelectronic performance and low fabrication cost,halide perovskite materials have become a research hotspot.However,the toxicity of lead and the instability of organic components severely restrict the commercial application.To solve these problems,metal cation substituted lead-free perovskite materials have received extensive attention.Among them,CsCu₂X₃ with one-dimensional electronic structure and Cs₃Cu₂X₅with zero-dimensional electronic structure have stable broad-spectrum emission,large Stokes shift and high photoluminescence quantum yield.Although copper halide perovskite materials with different morphologies and structures have been successfully applied to various optoelectronic devices,the development of large-area patterned array devices still faces challenges.In addition,there is debate on the interpretation of the luminescence mechanism of low-dimensional copper-based halidesBased on the current research status,this paper mainly explores the controllable growth of copper-based halide array films and single crystals,and further analyzes its wide-spectrum emission mechanism and application in photodetectors.The main research contents include the following four aspects:1.A vacuum-heating-assisted drop casting method was proposed to grow CsCu₂I₃ array films.It overcomes the incompatibility between traditional photolithography and perovskite materials,which realizes the precise and controllable growth of large-area CsCu₂I₃ pixel arrays,and the corresponding pixel films show uniform and dense morphology.This method is universal,and a variety of patterned arrays have been realized on different substrates with an accuracy of 100μm.Secondly,the optical properties of the film were explored.Combined with the analysis of the crystal structure and energy band structure,it was speculated that the shift of the Stokes photoluminescence spectrum at 266 nm in the CsCu₂I₃ film may be caused by the self-trapped excitons generated by the localized charge center formed by its one-dimensional electronic state structure.2.A 10×10 CsCu₂I₃ thin film flexible solar-blind photodetector array was prepared.The device shows the advantages of a wide photoresponse range and ultra-low light intensity detection,exhibiting an ultra-low detection threshold(6.1 n W cm^-2),as well as high photoresponsivity(62 A W^-1)and detectivity(1.4×10¹¹ Jones).Meanwhile,the device also exhibits good electrical stability and mechanical robustness,and the optoelectronic properties is basically unchanged after hundreds of stretching cycles.In addition,by polarizing and controlling the migration direction of a small amount of ions within the CsCu₂I₃ thin film,the p-i-n internal structure is formed through self-doping effect,enabling self-driven day-blind photodetection.3.The flexible detector array based on CsCu₂I₃ film realizes solar-blind light imaging and flame monitoring with warning capabilities.Through addressing 100 pixels and using current magnitude as contrast,clear solar-blind imaging is realized.Moreover,a hemispherical flame detector with longitude and latitude distribution is designed in combination with kirigami process,which exhibits the excellent anti-noise ability and could detect the distribution of multiple fire sources in space.On this basis,a real-time monitoring and early warning system of flame is developed,and multiple mobile terminals in the local area network can detect the space fire situation in real time.4.Large single crystals of high-quality copper-based halides have been successfully grown and its optical properties and detector applications were investigated.By employing an improved inverse temperature crystallization method and anti-solvent method,high-quality bulk single crystals of Cs₃Cu₂I₅ and Cs₃Cu₂Br₅ have been fabricated.The as-prepared single crystals exhibit bright blue fluorescence,with photoluminescence quantum yields as high as 95.93%for Cs₃Cu₂I₅ and 92.78%for Cs₃Cu₂Br₅.Through a comparative analysis with CsCu Cl₃ single crystal,it is inferred that the efficient fluorescence behavior of Cs₃Cu₂X₅single crystals originates from their zero-dimensional localized charge distribution,which limits the spin and orbital motion of excitons,leading to the fluorescence of self-trapped excitons.Subsequently,the Cs₃Cu₂X₅ single crystals was successfully utilized for photodetectors,realizing the detection of ultraviolet light and X-rays.