First Principles Calculation of Electrical and Optical Properties of Cu<sub>3</sub>AsO<sub>4</sub>: Promising Thin-Film Solar Cell Absorber from Nonferrous Metal Manufacturing By-Products

The stability and electronic structure of enargite-type Cu3AsO4 were investigated through first principles calculations. Although its synthesis has not been reported to date, the calculations indicate the possibility of synthesis of enargite-type Cu3AsO4. Enargite-type Cu3AsO4 is expected to possess a 1–1.2-eV band gap and a large optical absorption coefficient comparable to those of absorber materials for thin-film solar cells such as CdTe and GaAs. Enargite-type Cu3AsO4 is also expected to exhibit both p-type and n-type conduction by appropriate impurity doping. This property will enable use of this material in a p–n homojunction. In contrast, enargite-type Cu3AsS4 exhibits p-type conduction whereas n-type conduction is not expected. The results of this study indicate that enargite-type Cu3AsO4 is very promising as an absorber material for thin-film solar cells.