锗溴混合掺杂调控钙钛矿太阳电池光电特性的第一性原理研究

FIRST-PRINCIPLES STUDY ON REGULATION OF OPTICALPROPERTIES OF PEROVSKITE SOLAR CELLS BYGERMANIUM BROMIDE MIXED DOPING

采用第一性原理方法对锗溴混合掺杂下甲胺基钙钛矿(MAPbI3)材料的能带结构、态密度、介电函数和吸收光谱进行研究。构建MAPbI_(3)、MAPb_(0.75)Ge_(0.25)I_(3)、MAPbI_(2.5)Br_(0.5)、MAPb_(0.75)Ge_(0.25)I_(2.5)Br_(0.5)这4种钙钛矿结构模型并优化其结构,得出光电特性。研究结果表明,锗溴混合掺杂可改变价带顶与导带底位置及斜率,调控带隙值大小,同时混合掺杂也会改变价带顶与导带底的斜率,4种钙钛矿模型中锗溴混合掺杂时价带顶与导带底的斜率最小,有利于电子跃迁,提升光电转换效率;掺杂锗可提高钙钛矿在可见光区的吸收性能,掺杂溴对钙钛矿光学特性影响不大。

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:MAPbI_(3),MAPb_(0.75)Ge_(0.25)I_(3),MAPbI_(2.5)Br_(0.5),and MAPb_(0.75)Ge_(0.25)I_(2.5)Br_(0.5).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.