High-Efficiency Cu2O-Based Heterojunction Solar Cells Fabricated Using a Ga2O3 Thin Film as N-Type Layer

High-efficiency heterojunction solar cells consisting of a nondoped Ga 2 O 3 thin film as an n-type semiconductor layer and a p-type Cu 2 O sheet as the active layer as well as the substrate, prepared by thermally oxidizing a Cu sheet, are demonstrated. The use of an n-type Ga 2 O 3 thin film can greatly improve the performance of n-Ga 2 O 3 /p-Cu 2 O heterojunction solar cells. The highest efficiency of 5.38% was obtained in an Al-doped ZnO/Ga 2 O 3 /Cu 2 O heterojunction solar cell fabricated with an n-Ga 2 O 3 thin-film layer prepared at room temperature with a thickness of 75 nm by a pulsed laser deposition method.