Modulated Electronic And Optical Properties Of Novel Halogen Perovskite Materials

Perovskites have received much attention in applications such as optoelectronic devices due to its excellent optoelectronic properties and structural diversity.How to further improve the optical properties of perovskite materials and increase the optical and electrical performance has become a focus of the research today.Based on First-principles calculation,to obtain excellent perovskite materials,the electronic structure and optical properties of inorganic halogen perovskite materials were regulated by varying the doping concentration or applying pressure in the thesis.The specific research content is as follows:The first chapter,the research status,structure,applications and preparation methods of perovskite materials were introduced.Especially,the contents of this paper were also presented.The second chapter,the related theories such as First principles,density functional,Hartee-Fock method,Thomas-Fermi approximation,Hohenberg-Kohn theorem,exchange correlation functional and pseudopotential theory were presented.The related software and calculation methods were also introduced.The third chapter,the electronic structure and optical properties of Cs Pb₂Cl₅ perovskite materials were modulated by changing the concentration of I doping and intensity of the external pressure.The optical properties of the perovskite material can be effectively controlled through doping with I at different concentrations to find the optimal doping concentration.The optical properties of perovskite material can be further improved by applying different external pressure.The fourth chapter,by doping with different concentrations of I and pressure regulation,the electronic structure and optical properties of perovskite Cs₂Ag Bi Br₆were improved.The binding energy was calculated to determine the most likely occupied lattice site of doping ion and on the basis,the changes in the electronic and optical properties are analyzed.Further studies have been made on the regulation of electronic structural properties and optical properties such as energy band structure,charge density and density of states.The fifth chapter,for double halide perovskite Cs₃Bi Br₆,it is proposed that the electronic structure and optical properties of perovskite Cs₃Bi Br₆ are effectively improved by adjusting the external pressure and doped ions.The calculation results show the site occupancy rate of I doping according to the binding energy.After determining the site occupancy,the electronic structure properties of perovskite Cs₃Bi Br₆:I^-at the site were analyzed.The regulation of optical propertieswith different doping concentrations or pressures were studied by means of energy band structure,charge density,density of states and so on.