Enhancement of the open circuit voltage of Cu2O/Ga2O3 heterojunction solar cells through the mitigation of interfacial recombination

Thin film solar cells were fabricated using cuprous oxide (Cu2O) absorber layers grown by chemical vapor deposition (CVD) and gallium oxide (Ga2O3) buffer layers grown by atomic layer deposition (ALD) on the cuprous oxide CVD films. The in-situ formation of heterojunction in the same deposition system without exposure to oxygen-rich ambient was found to be effective in mitigating the creation of detrimental cupric oxide (CuO) at the interface, resulting in a pristine photovoltaic junction capable of delivering an enhanced open-circuit voltage of 1.78 V. Numerical device simulations of a novel two-layer absorber architecture (CVD-Cu2O on ECD-Cu2O) showed promising possibilities (theoretical 13.2 % efficiency) for a solar cell combining in-situ junction formation with electrochemical deposition of the absorber layer.