High-Efficiency Ferroelectric-Film Solar Cells with an n-type Cu2O Cathode Buffer Layer

Abstract

Becasue of the existence of interface Schottky barriers and depolarization electric field, ferroelectric films sandwiched between top and bottom electrodes are strongly expected to be used as a new kind of solar cells. However, the photocurrent with a typical order of μA/cm² is too low to be practical. Here we demonstrate that the insertion of an n-type cuprous oxide (Cu₂O) layer between the Pb(Zr,Ti)O₃ (PZT) film and the cathode Pt contact in a ITO/PZT/Pt cell leads to the short-circuit photocurrent increasing 120-fold to 4.80 mA/cm² and power conversion efficiency increasing of 72-fold to 0.57% under AM1.5G (100 mW/cm²) illumination. Ultraviolet photoemission spectroscopy and dark J–V characteristic show an ohmic contact on Pt/Cu₂O, an n⁺–n heterojunction on Cu₂O/PZT and a Schottky barrier on PZT/ITO, which provide a favorable energy level alignment for efficient electron-extraction on the cathode. Our work opens up a promising new method that has the potential for fulfilling cost-effective ferroelectric-film photovoltaic.