Anomalous photovoltaic effect in Na0.5Bi0.5TiO3-based ferroelectric ceramics based on domain engineering

The anomalous photovoltaic (APV) effect is promising for high-performance ferroelectric materials and devices in photoelectric applications. However, it is a challenge how to tune the APV effect by utilizing the characteristic structure of ferroelectrics. Here, a domain engineering strategy is proposed to enhance the APV effect in lead-free 0.88(Na0.5Bi0.5TiO3)-0.12(Ba1–1.5xSmxTiO3) (NBT-BST) ferroelectric ceramics. By tuning the domain size based on Sm3+ doping, a maximum open-circuit voltage (VOC) of 18.1 V is obtained when Sm3+ content is 0.75%, which is much larger than its bandgap (Eg). The mechanism of this large VOC originates from the multiple positive effects induced by the small-size domain, where decreasing domain size enhances ferroelectric polarization and net interface barrier potential, leading to a large driving electric field. Moreover, the APV effect exhibits a giant temperature sensitivity due to the dramatic evolution of small-size domain in the temperature field. This work sheds light on the exploration of ferroelectrics with APV effect and inspires their future high-performance optoelectronic device applications.