Enhanced photovoltaic-pyroelectric coupled effect of BiFeO3/Au/ZnO heterostructures

The photovoltaic properties of ferroelectric films and ferroelectric-semiconductor heterostructures have been extensively studied due to their application prospects in photodetection, energy conversion and nonvolatile storage. However, light-induced pyroelectric effect accompanied by the photovoltaic effect of ferroelectric-semiconductor heterostructures lacks sufficient attention. Herein, BiFeO3 (BFO)/Au/ZnO heterostructures are constructed by controlling sputtering time of Au nanoparticles and the regulation mechanism of integrating pyroelectric and photovoltaic effects is explored. The short-circuit photocurrent density of the optimal BFO/Au/ZnO heterostructures is nearly 1.4 times that of BFO/ZnO heterostructures under 405 nm light illumination. Moreover, BFO/Au/ZnO heterostructures broaden the response wavelength from 360 nm to 1060 nm light beyond the bandgap limitation. Compared with merely the photovoltaic effect found in BFO films and BFO/ZnO heterostructures, BFO/Au/ZnO heterostructures display the photovoltaic-pyroelectric coupled effect that is associated with light-induced temperature variation rate and band alignment by introducing Au nanoparticles into BFO and ZnO layers. The implementation of the photovoltaic-pyroelectric coupled effect endows BFO/Au/ZnO heterostructures with outstanding photoelectric performances modulated by self-polarization phenomenon and band bending. This work not only provides in-depth understanding about the photovoltaic-pyroelectric coupled effect of ferroelectric-metal-semiconductor heterostructures, but also provides an effective and facile route to design high-performance photoelectric related devices with wideband response.