Solution-Processed Copper-Doped Chromium Oxide with Tunable Oxygen Vacancy for Crystalline Silicon Solar Cells Hole-Selective Contacts

Compared with vacuum evaporation, metal oxides deposited by solution process exhibit advantages, for example, dopants can be easily incorporated in a wide range and the contents are easy to be regulated by changing the composition of precursors. Herein, solution-processed p-type copper-doped chromium oxide (Cu:CrO x ) films with tunable oxygen vacancy are demonstrated via a postannealing process. The synthetic and postannealing temperature have a significant impact on the chromium cation oxidation state in the Cu:CrO x films, leading to the variation of work function for the oxide films. By adjusting the work function of Cu:CrO x films, a low contact resistivity of 95 mΩ cm 2 can be realized for the Ag/Cu:CrO x /p-Si contact. Finally, the optimized Cu:CrO x films are used as the hole transporting layer in c-Si solar cells, showing an increased power conversion efficiency from 15.2% (without Cu:CrO x ) to 16.9% (with Cu:CrO x ). The results show an effective stage to use p-type metal oxides as a hole-selective layer in c-Si solar cells.