FIRST-PRINCIPLES STUDY ON REGULATION OF OPTICAL PROPERTIES OF PEROVSKITE SOLAR CELLS BY GERMANIUM BROMIDE MIXED DOPING
The band structure,state density,dielectric function,and absorption spectrum of germanium-bromine mixed-doped methylamino-based perovskite(MAPbI3)materials were investigated using first-principles methods.Four perovskite structure models were constructed:MAPbI3,MAPb0.75Ge0.25I3,MAPbI2.5Br0.5,and MAPb0.75Ge0.25I2.5Br0.5.The structures of the four perovskites were optimized,and their photoelectric characteristics were obtained.The results indicate that germanium and bromine doping can alter the position and slope of the valence band top and conduction band bottom,adjusting the band gap value.The smallest slope of the valence band top and conduction band bottom is observed when germanium and bromine are jointly doped,among the four structures.This is conducive to electron transition and enhances photoelectric conversion efficiency.Germanium improves the absorption performance of perovskites in the visible light region,while bromine has a minimal effect on the optical properties of perovskites.
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