Electrical and optical properties of TCO–Cu2O heterojunction devices

Abstract This report describes the electrical and photovoltaic properties in heterojunction devices consisting of a cuprous oxide (Cu2O) sheet and a transparent conducting oxide (TCO) thin film, such as In2O3, ZnO, In2O3:Sn (ITO), ZnO:Al (AZO) or AZO–ITO (AZITO) multicomponent oxide, prepared by pulsed laser deposition (PLD). Undoped In2O3–Cu2O heterojunctions prepared by PLD exhibited ohmic current–voltage (I–V) characteristics. The ZnO–Cu2O and AZO–Cu2O devices exhibited better rectifying I–V characteristics and photovoltaic properties than the ITO–Cu2O devices. It was found that the obtainable I–V characteristics and photovoltaic properties were considerably affected by the TCO film deposition conditions. An open-circuit voltage (VOC) of 0.4 V, a short-circuit current density (JSC) of 7.1 mA/cm2, a fill factor (F.F.) of 0.4 and an energy conversion efficiency (η) of 1.2% were obtained in an AZO–Cu2O device under AM2 solar illumination. The VOC, JSC, F.F. and η obtained in AZITO–Cu2O heterojunctions increased as the Zn/(Zn+In) atomic ratio was increased.