Heterojunction solar cell with 6% efficiency based on an n-type aluminum-gallium-oxide thin film and p-type sodium-doped Cu_2O sheet

摘要

In this paper, we describe efforts to enhance the efficiency of Cu_2O-based heterojunction solar cells fabricated with an aluminum-gallium-oxide (Al-Ga-O) thin film as the n-type layer and a p-type sodium (Na)-doped Cu_2O (Cu_2O:Na) sheet prepared by thermally oxidizing copper sheets. The optimal Al content [X; Al/(Ga + Al) atomic ratio) of an Al_x-Ga_(1-x)-O thin-film n-type layer was found to be approximately 2.5 at. %. The optimized resistivity was approximately 15 Ω cm for n-type Al_x-Ga_(1-x)-O/p-type Cu_2O:Na heterojunction solar cells. A MgF_2/AZO/Al_(0.025)-Ga_(0.975)-O/ Cu_2O:Na heterojunction solar cell with 6.1% efficiency was fabricated using a 60-nm-thick n-type oxide thin-film layer and a 0.2-mm-thick Cu_2O:Na sheet with the optimized resistivity.