Dominant Defect Complexes in Cuprous Oxide

Abstract

The world’s energy demand is increasing and the conversion of existing energy sources to renewable alternatives is crucial in reducing CO2 emissions. A major contributor to the realization of this is solar cells, which are currently the fastest growing renewable energy resource, and will need to grow at an accelerating rate to meet the demand for renewable energy. Cu2O is a promising semiconductor for solar cell applications and could be utilized in exciting applications such as semitransparent and flexible substrates. It is a high bandgap material, which opens the possibility of high-efficiency tandem solar cell applications. The efficiency of Cu2O-based solar cells has yet to reach its full potential. In this work, Cu2O is studied to investigate its electrical properties related to solar cell performance. We have investigated both bulk and thin-film Cu2O to better understand the reason behind the limited performance seen in experimental Cu2O-based solar cells. It is proven challenging to conclusively identify and control the defects within the Cu2O material. The importance of a deep acceptor present in the studied samples is particularly interesting. The effect of such an acceptor is investigated through device simulations and demonstrates clearly how high concentrations will limit Cu2O-based solar cell performance.