基于ZnTe_(1-x)Y_x(Y=O,S,Se)中间带光伏材料光电性能的第一性原理研究

Optoelectronic Performance of ZnTe_(1-x)Y_x(Y=O,S,Se)Intermediate Band Photovoltaic Material from First Principles

采用基于密度泛函理论框架下的第一性原理方法计算了高失配三元合金ZnTe1-xYx(Y=O,S,Se)的能带结构、电子特性与光学性能。通过对半导体态密度的计算证实了在闪锌矿结构的ZnTe中掺杂O、S或Se原子可能得到独立的中间带结构,该结构可提高光伏材料对能量低于母体半导体带隙光子的吸收效率。研究结果表明,中间带在ZnTe1-xOx中是由掺杂的O原子的2p态与处于导带的Zn原子的4s态耦合而成,符合能带反交叉模型。另外,与ZnTe1-xSx和ZnTe1-xSex相比,随着掺杂O浓度的变化,ZnTe1-xOx的中间带表现出较高的稳定性主要是因为O与Te之间存在最大的电负性差。

By using the first-principles calculation based on density functional theory,the electronic structures and optical properties of highly mismatched ZnTe1-xYx （Y=O,S,Se） ternary alloys were investigated.The results show that an isolated intermediate electronic band structure can be formed in ZnTe1-xOx,leading to a significant optical absorption in the whole energy range of the solar spectrum.It is found that the intermediate band states should be described as a result of the coupling between O 2p states with Zn 4s states,which is consistent with the band anticrossing model.Besides,compared with ZnTe1-xSx and ZnTe1-xSex,the IB in ZnTe1-xOx shows the highest stabilization with the increase of O concentration resulting from the largest electro-negativity difference between O and Te.