Evaluation of Photovoltaic Materials within the Cu-Sn-S Family

Next-generation thin film solar cell technologies require earth abundant photovoltaic absorber materials. Here we demonstrate an alternative approach to design of such materials, evaluating candidates grouped by constituent elements rather than underlying crystal structures. As an example, we evaluate thermodynamic stability, electrical transport, electronic structure, optical and defect properties of Cu-Sn-S candidates using complementary theory and experiment. We conclude that Cu₂SnS₃ avoids many issues associated with the properties of Cu₄SnS₄, Cu ₄Sn₇S₁₆, and other Cu-Sn-S materials. This example demonstrates how this element-specific approach quickly identifies potential problems with less promising candidates and helps focusing on the more promising solar cell absorbers.