Non-equilibrium alloying controls optoelectronic properties in Cu_2O thin films for photovoltaic absorber applications

摘要

Cuprous oxide (Cu_2O) has recently received much attention as a candidate material for oxide photovoltaics. However, its low absorption coefficient due to the symmetry forbidden band gap and low intrinsic p-type doping level are obstacles for further advancing the performance of Cu_2O thin film solar cells. Following computational predictions on the band gap, doping, and optical properties, we report combinatorial synthesis and characterization of Cu_(2-2x)Zn_xO_(1-y)Se_y thin film alloys and the associated device modeling results. We show that the absorption and the conductivity can be independently controlled by Se and Zn content, thereby devising a possible route to design of more efficient oxide photovoltaics and tandem solar cells.