Study On The Growth And Properties Of Methylammonium Lead Halide Perovskite Single Crystal Materials

Recently,organometal halide perovskites materials which show excellent optoelectronic properties such as high carrier mobility,long carrier diffusion length and high optical absorption coefficient have attracted increasing interest owing to their academic importance and promising application perspectives in the fields of solar cell,field-effect transistors(FETs)and light emitting diodes(LEDs),etc.Compared with single crystal,powder and polycrystalline perovskite thin films are more prone to be argued on the carrier mobility,mechanism of optoelectronic conversion,stability,and so on.Despite of the abundant reported cases of powder and thin film materials,the single crystal materials are still rarely discovered.The lower defect density,higher carrier mobility and longer carrier diffusion length provide a better platform to investigate the basic photophysical properties of single crystal materials.Therefore,research on the growth of bulk crystals of organometal halide perovskites materials is strikingly desirable.The dissertation contains five chapters,and the main contents of each chapter are as follows:In chapter one,firstly,the research background of organometal halide perovskites was introduced.Then,the influences of crystal structures on different components were emphasized.Thirdly,perovskite materials with different dimensions were analyzed.Finally,a focused summary of the growth methods and research status of organometal halide perovskites bulk crystals were proceeded.Based on these backgrounds,the topic basis,design ideas and research contents of this dissertation were presented,and the main contents of each chapter were summarized.The second chapter is about experimental methods and characterizations.We described reagents used in the experiments and growth apparatus for these perovskite single crystals.And measurements and instruments for some intrinsic properties of materials were elaborated in detail.In chapter three,we reported the bulk growth and properties of CH3NH3PbBr3 single crystals.The CH3NH3PbBr3 bulk single crystals with centimeter magnitude were grown by the solution cooling method.We summarized the growth methods and problems of these crystal materials,confirmed their crystal structures,and characterized the fundamental properties.The fourth chapter is about the bulk growth and properties of CH3NH3Pb(Cl1-xBrx)3 single crystal.On the basis of the experience of growing CH3NH3PbBr3bulk single crystal,the mixed halide crystals were also grown.A series of CH3NH3Pb(Cl1-xBrx)3 perovskite single crystals with different ratios of Cl/Br were grown.The single crystal structures were confirmed and the fundamental physical properties were characterized.The last chapter is a summary of the whole dissertation.We revealed the main contents,conclusions,creative work and further work to be done in the future.