摘要
GeSe has recently emerged as a photovoltaic absorber material due to its attractive optical and electrical properties as well as earth abundancy and low toxicity.However,the efficiency of GeSe thin-film solar cells(TFSCs)is still low compared to the Shockley–Queisser limit.Point defects are believed to play important roles in the electrical and optical properties of GeSe thin films.Here,we perform first-principles calculations to study the defect characteristics of GeSe.Our results demonstrate that no matter under the Ge-rich or Se-rich condition,the Fermi level is always located near the valence band edge,leading to the p-type conductivity of undoped samples.Under Se-rich condition,the Ge vacancy(V_(Ge))has the lowest formation energy,with a(0/2–)charge-state transition level at 0.22 eV above the valence band edge.The high density(above 10^(17)cm^(-3))and shallow level of VGeimply that it is the p-type origin of GeSe.Under Se-rich growth condition,Seihas a low formation energy in the neutral state,but it does not introduce any defect level in the band gap,suggesting that it neither contributes to electrical conductivity nor induces non-radiative recombination.In addition,Gei introduces a deep charge-state transition level,making it a possible recombination center.Therefore,we propose that the Se-rich condition should be adopted to fabricate high-efficiency GeSe solar cells.
作者
闫赛超
魏金宸
王珊珊
黄梦麟
吴宇宁
陈时友
Saichao Yan;Jinchen Wei;Shanshan Wang;Menglin Huang;Yu-Ning Wu;Shiyou Chen(Key Laboratory of Polar Materials and Devices(MOE)and Department of Electronics,East China Normal University,Shanghai 200241,China;State Key Laboratory of ASIC and System,School of Microelectronics,Fudan University,Shanghai 200433,China)
基金
supported by Shanghai Academic/Technology Research Leader(Grant No.19XD1421300)
the National Natural Science Foundation of China(Grant No.12174060)
Program for Professor of Special Appointment(Eastern Scholar TP2019019)
the National Key Research and Development Program of China(Grant No.2019YFE0118100)
State Key Laboratory of ASIC&System(Grant No.2021MS006)
Young Scientist Project of MOE Innovation Platform。