The internally stacked CuO/Cu 2 O photoactive layers were prepared by electrodeposition of the Cu 2 O layer followed by heating in air. The 1.4 eV-p-CuO layer was heteroepitaxially grown on the Cu 2 O layer accompanied by the formation of nanopores by heating at 573 K, and both the CuO and Cu 2 O layers possessed excellent semiconductor qualities with band-edge emission in the visible light region. The internally stacked CuO/Cu 2 O photoactive layer revealed the photovoltaic performance in a corresponding wide photon energy range due to the utilization of the photovoltaic ability for both the CuO and Cu 2 O layers by applying a bias voltage. Heating at 673 K induced transfer of the thickened CuO layer to the polycrystalline phase and coalescence of nanopores, resulting in the disappearance of the light emission and photovoltaic performance, irrespective of the bias voltage. The crystal and semiconductor qualities for both the CuO and Cu 2 O layers affected the photovoltaic performance for the internally stacked CuO/Cu 2 O photoactive layer.