Band gap temperature-dependence and exciton-like state in copper antimony sulphide, CuSbS2
Band gap temperature-dependence and exciton-like state in copper antimony sulphide, CuSbS2
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DOI：
10.1063/1.5030207
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发表时间：
2018-06
期刊：
影响因子：
6.1
通讯作者：
M. Birkett;Christopher N. Savory;M. Rajpalke;W. Linhart;T. J. Whittles;J. Gibbon;Adam W. Welch;I. Mitrovic;A. Zakutayev;D. Scanlon;T. Veal
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文献类型：
--
作者：
M. Birkett;Christopher N. Savory;M. Rajpalke;W. Linhart;T. J. Whittles;J. Gibbon;Adam W. Welch;I. Mitrovic;A. Zakutayev;D. Scanlon;T. Veal
通过傅里叶变换红外光谱研究了所提出的光伏吸收剂硫化铜锑（CuSbS2）的带隙的温度依赖性。在 300 K 和 4.2 K 之间，直接能隙从 1.608 eV 上升到 1.694 eV。在 200 K 以下，在 1.82 eV 的吸收边缘上方会出现类似激子的特征。第一原理计算评估了能带结构、能带对称性和偶极子选择规则，表明某些激子光学跃迁的吸收明显增强。预测的介电谱和吸收谱与椭圆光度法测定的谱之间存在惊人的一致性，表明在 2.2 eV 处通过 105cm-1 时吸收迅速增强。这些结果表明，由于多晶 CuSbS2 材料中异常强的电子-空穴相互作用产生强光吸收，因此具有有益的光伏性能。
The temperature-dependence of the band gap of the proposed photovoltaic absorber copper antimony sulphide (CuSbS2) has been studied by Fourier-transform infrared spectroscopy. The direct gap rises from 1.608 to 1.694 eV between 300 and 4.2 K. Below 200 K an exciton-like feature develops above the absorption edge at 1.82 eV. First-principles calculations evaluate band structure, band symmetries, and dipole selection rules, suggesting distinctly enhanced absorption for certain excitonic optical transitions. Striking consistency is seen between predicted dielectric and absorption spectra and those determined by ellipsometry, which reveal rapidly strengthening absorption passing 105cm-1at 2.2 eV. These results suggest beneficial photovoltaic performance due to strong optical absorption arising from unusually strong electron-hole interactions in polycrystalline CuSbS2material.