First-principles study of the band gap tuning and doping control in CdSexTe1-x alloy for high efficiency solar cell  

作　　者：Jingxiu Yang Su-Huai Wei 杨竞秀;魏苏淮(Department of Materials Science and Engineering,Jilin Jianzhu University,Changchun 130118,China;Beijing Computational Science Research Center,Beijing 100193,China)

机构地区：[1]Department of Materials Science and Engineering,Jilin Jianzhu University,Changchun 130118,China [2]Beijing Computational Science Research Center,Beijing 100193,China

出　　处：《Chinese Physics B》2019年第8期16-21,共6页中国物理B（英文版）

基　　金：Project supported by the National Key Research and Development Program of China(Grant No.2016YFB0700700);the National Natural Science Foundation of China(Grant Nos.51672023,11847043,11634003,and U1530401);the Science Challenge Project(Grant Nos.TZ2016003 and TZ2018004)

摘　　要：CdTe is one of the leading materials for low cost,high efficiency thin-film solar cells with a nearly ideal band gap of 1.48 eV.However,its solar to electricity power conversion efficiency(PCE)is hindered by the relatively low open circuit voltage(VOC)due to intrinsic defect related issues.Here,we propose that alloying CdTe with CdSe could possibly improve the solar cell performance by reducing the"ideal"band gap of CdTe to gain more short-circuit current from long-wavelength absorption without sacrificing much VOC.Using the hybrid functional calculation,we find that the minimum band gap of the CdTe1-xSex alloy can be reduced from 1.48 eV at x=0 to 1.39 eV at x=0.32,and most of the change come from the lowering of the conduction band minimum.We also show that the formation of the alloy can improve the p-type doping of CuCdimpurity based on the reduced effective formation energy and nearly constant effective transition energy level,thus possibly enhance VOC,thus PCE.CdTe is one of the leading materials for low cost, high efficiency thin-film solar cells with a nearly ideal band gap of 1.48 eV. However, its solar to electricity power conversion efficiency（PCE） is hindered by the relatively low open circuit voltage（VOC） due to intrinsic defect related issues. Here, we propose that alloying CdTe with CdSe could possibly improve the solar cell performance by reducing the "ideal" band gap of CdTe to gain more short-circuit current from long-wavelength absorption without sacrificing much VOC. Using the hybrid functional calculation, we find that the minimum band gap of the CdTe1-xSex alloy can be reduced from 1.48 eV at x = 0 to 1.39 eV at x = 0.32, and most of the change come from the lowering of the conduction band minimum. We also show that the formation of the alloy can improve the p-type doping of CuCdimpurity based on the reduced effective formation energy and nearly constant effective transition energy level, thus possibly enhance VOC, thus PCE.

关 键 词：ALLOY BOWING effect DOPING Ⅱ-Ⅵsemiconductors 

分 类 号：O4[理学—物理]