Preparation Of Tin-based Perovskite Nanomaterials And Study On Their Photoelectric Properties

In recent years,metal halide perovskite nanomaterials have been attracted widespread attention since the adjustable emission spectrum,high fluorescence quantum yield,simple preparation method and low cost.And metal halide perovskite nanomaterials have unique application value in the field of solar cells,electroluminescent diodes,field effect transistors,lasers and switching devices.Considering the toxicity of lead-based perovskites and the sensitivity to water,heat,light and other factors,developing non-lead-stabilized perovskite materials have become a hot topic in this field.In this paper,a series of Cs₂SnI₆ perovskite nanomaterials with different morphologies and an?OLA?_xSnI₄ perovskite quantum dot fluorescent material were prepared based on the stable tetravalent tin in the environment.The photoelectric properties and applications were characterized and analyzed.Generally,most reported Cs₂SnI₆ nanomaterials are mainly prepared by the traditional "hot injection method".However,the synthesis process of this method is complicated,and has high requirements on the preparation environment and preparation process,which is not easy to control and large-scale synthesis.Based on the preparation method of lead-based perovskite nanomaterials,actively explore a new and simplified solvothermal preparation process to prepare Cs₂SnI₆ nanomaterials,and propose to change its morphology and stability by changing the proportion and amount of ligands.Among them,when the ratio of oleylamine and oleic acid is equal,an ultra-thin Cs₂SnI₆ two-dimensional material can be obtained,which shows good environmental stability.The XRD results show that there is no obvious decomposition after being left in the air for 270 days,and the steady-state photovoltage The test estimates that the band gap of the material is 1.62 eV,and the transient surface photovoltage results indicate that the material is an n-type semiconductor.Then,using Cs₂SnI₆ nanomaterials with different morphologies as the active layer,a non-volatile resistive memory with the structure of ITO/PMMA/Cs₂SnI₆/Al₂O₃/Ag was prepared.The current did not decay significantly after 600 cycles.At a constant voltage of 2 V,the ON/OFF state current retention time exceeded 10000 s,demonstrating good device stability.In addition,in this paper,SnI₄ and OLA were used as reaction raw materials,and the same new tin-based perovskite?OLA?was prepared in one step using three different reaction conditions?"heat and stir","stirring" and "ultrasonic"?.The SnI₄ quantum dot fluorescent material,from heating and stirring" to "ultrasonic",the average particle size of the material gradually increases,followed by 2.67 nm,3.2 nm and 4.0 nm,the material prepared by "heating and stirring" is more crystalline than the latter two Poor.?OLA?_xSnI₄ quantum dots prepared under different conditions show orange light emission under ultraviolet lamp,and the emission peak positions of PL spectrum are the same,all have obvious emission peaks at 582 nm,616 nm,653 nm,and 694 nm.