Density Functional Theory Studies The Optical And Electrical Properties Of ?-CsPbI₃ Perovskite Materials Co-doped With Mg And Br

?-CsPbI₃ all-inorganic perovskite material has good stability and high photoelectric conversion efficiency.It has become the focus of attention in recent years,but?-CsPbI₃ perovskite material contains toxic Pb element,which is not conducive to the commercial production of all-inorganic perovskite solar cells.Alkaline earth metals are often used to partially replace the Pb element in?-CsPbI₃,and achieved many excellent results,Mg doping has the most significant effect on the band gap of?-CsPbI₃,but Mg cannot finely adjust the band gap of?-CsPbI₃ perovskite materials.Halogen element doping has been widely studied to adjust the band gap of organic-inorganic perovskite materials,and the results show that Br doping can finely adjust the band gap of organic-inorganic perovskite materials.Therefore,in order to reduce the Pb content of the?-CsPbI₃ perovskite material and appropriately adjust the band gap of the?-CsPbI₃ perovskite material,the band gap of the doped Cs Pb I₃ perovskite material is suitable for perovskite solar cell.In this paper,the co-doping method of Mg and Br was used to study the?-CsPbI₃ perovskite material,the following work was carried out.Applying CASTEP calculation module of Material Studio software,the first-principles calculation of a series of all-inorganic perovskite materials has the structural formula Cs Pb_1-xMg_xI_3-yBr_y?x=0,0.125,0.25;y=0,1,2,3?.The doping concentration of Mg and Br was changed to establish a model,and the structure model was optimized by GGA and PBE functions.Based on the optimized model,the electrical and optical properties of Cs Pb_1-xMg_xI_3-yBr_y?x=0,0.125,0.25;y=0,1,2,3?were simulated.Research the effects of Mg and Br doping on the structure and optoelectronic properties of?-CsPbI₃ perovskite materials,based on the calculation results,the band gap of the material after co-doping of Mg and Br was most suitable for the perovskite solar cell Light absorbing layer.The results show that Mg doping can expand the band gap of ?x=0,0.125,0.25;y=0,1,2,3?changed from a direct bandgap semiconductor to an indirect bandgap semiconductor,but after calculation,Cs Pb_0.875Mg_0.125IBr₂ is still a direct bandgap semiconductor.Doping of Br element can finely adjust the band gap of Cs Pb_1-xMg_xI_3-yBr_y?x=0,0.125,0.25;y=0,1,2,3?.After Mg and Br co-doping,the show that the band gap of Cs Pb_1-xMg_xI_3-yBr_y?x=0,0.125,0.25;y=0,1,2,3?can be finely adjusted between 1.301e V-2.292e V.Among all the materials in this study,the band gap of Cs Pb_0.875Mg_0.125I₂Br is most suitable to be 1.523e V,and the optical absorption performance is closest to that of?-CsPbI₃.therefore,Cs Pb_0.875Mg_0.125I₂Br perovskite material can be an ideal candidate for the light absorption layer of perovskite solar cells.