Design And Optimization Of Perovskite Solar Cell Materials

In recent years,perovskite solar cells because of its production process is simple,low cost,high photoelectric conversion efficiency has aroused widespread concern at home and abroad researchers.At present,the highest photoelectric conversion efficiency of perovskite solar cells has reached 22.1%,and its further development is expected to solve the bottleneck of the development of solar cell cost and efficiency.However,the long-term stability of perovskite solar cells and the negative impact on the sustainable development of ecological environment due to the presence of lead in heavy metals lead to serious restrictions on its industrial development.Therefore,the stability of perovskite materials and the problem of lead substitution have become the focus of research in this field.Due to the relative lack of research on the relationship between the structure of perovskite-type materials and their stability and photoelectric properties,the rational design and selection of new materials are limited.In order to reveal the influence of element composition,geometry and electronic structure on the photoelectric properties and stability of the materials,the ABX₃-type perovskite materials were firstly studied by means of studying the influence of A,B,X.The structure stability and the electronic structure of MA 3Bi2I9?MBI?,which is a kind of new kind of calcium-titanium material,were analyzed and the influence of its position on the electronic structure and stability of the electronic structure was analyzed.And the stability of the perovskite materials in humid environment was systematically analyzed.In the first part of this paper,the background and research status of this work are systematically summarized.The second part mainly introduces the first-principles calculation method itself and the calculation software and parameters.The third to the fifth part is the main body of the paper.The third part is based on the density functional theory,based on the structure of CH₃NH₃ PbI₃,the structure model of ABX₃ is established and optimized by CASTEP software.The structure and electronic properties of each system are calculated by first-principles calculation method.The density of states,the cohesive energy,and so on are analyzed in detail.The substitution of A and B metal cations for different small molecular groups was carried out by doping calculations for Cl,Br,I and pseudohalogens in the X-position.The changes in the structure and elements of A,B and X were investigated for ABX₃ perovskite structure and electronic properties;In the fourth part,the MBX model was established and optimized by CASTEP software.It was analyzed whether the two-layer layered perovskite materials could be used as light absorbing materials for perovskite solar cells,and the change of structure of the MBX perovskite And electronic properties.In the fifth part,the adsorption properties of MAPbI₃,FAPbI₃ and MAPbI₃-CHONH₃ PbI₃ to water molecules were studied by VASP software,and their stability in moisture environment was analyzed.It is more appropriate to analyze the material as a light absorbing layer of a perovskite solar cell by calculation.The sixth part is summary and prospect.