CsCu5Se3: A Copper-Rich Ternary Chalcogenide Semiconductor with Nearly Direct Band Gap for Photovoltaic Application

Discovery of new semiconductor candidates with suitable band gaps is a challenge for optoelectronic application. A facile solvothermal synthesis of a new ternary chalcogenide semiconductor CsCu5Se3 is reported. The telluride CsCu5Te3 is also predicted to be stable. CsCu5Se3 is isostructural with CsCu5S3 (space group Pmma). The band gap calculations of these chalcogenide semiconductors using hybrid density functional theory indicate nearly direct band gaps, and their values (about 1.4 eV) were confirmed by the optical absorption spectroscopy. These alkali metal copper chalcogenides are interesting examples of copper-rich structures which are commonly associated with favorable photovoltaic application.寻找具备合适带隙的新型半导体候选材料，是光电子应用领域面临的一项核心挑战。本研究报道了一种通过简便溶剂热法合成的新型三元硫族化物半导体CsCu5Se3，并预测碲化物CsCu5Te3同样具有结构稳定性。CsCu5Se3与CsCu5S3为同构结构（空间群为Pmma）。采用杂化密度泛函理论对这类硫族化物半导体进行带隙计算的结果显示，其带隙近乎为直接带隙，且带隙值（约1.4 eV）经光吸收光谱测试得到了验证。这类碱金属铜基硫族化合物是一类颇具研究价值的富铜结构范例，通常在光伏应用中具备优异的应用潜力。