Fabrication of PZT/CuO composite films and their photovoltaic properties

The existence of the Schottky barriers at the top and bottom electrodes of the ferroelectric thin film sandwich structure makes it difficult to separate and collect electron-hole pairs, thus limiting the enhancement of the photocurrent. In this paper, Pb(Zr,Ti)O₃ (PZT) and composite structure of PZT/CuO films are prepared by a sol-gel method and their photovoltaic properties have been investigated. It is found that the PZT/CuO films show a short circuit photocurrent density (J_SC) enhanced by nearly 6 times and power conversion efficiency (PCE) increased by six-fold when compared to those of the PZT film. The increase of photovoltaic response is due to the internal electric field of PZT/CuO p–n junction, which plays an important role in driving the photo-generated carriers. The Ohmic contact between the interfaces of LNO/PZT and CuO/Pt also reduce the resistance of the transportation of photogenerated carriers. Furthermore, the J_SC of PZT/CuO film are observed to be 0.03 and 0.013 mA/cm² after upward poling and downward poling, respectively, indicating that the photocurrent can be modulated by the direction of the polarization electric field. The photovoltaic effect of composite films and its potential mechanism are also explored. This work provides an efficient approach to develop ferroelectric film based on photovoltaic devices.