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(Na_0.5Bi_0.5TiO₃)-0.12(Ba_1-1.5xSm_xTiO₃) (NBT-BST) ferroelectric ceramics. By tuning the domain size based on Sm³⁺ doping, a maximum open-circuit voltage (V_OC) of 18.1 V is obtained when Sm³⁺ content is 0.75%, which is much larger than its bandgap (E_g). The mechanism of this large V_OC 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.

The immense potential of flexible energy storage materials applied in wearable electronic devices has stimulated a lot of science researches on manufacturing technology and performance optimization. Herein, an all-inorganic flexible ferroelectric film with multilayer heterostructure is prepared based on Mn doped Bi_0.5Na_0.5TiO₃BiNi_0.5Zr_0.5O₃ (Mn: BNT-BNZ) and Bi_0.5Na_0.5TiO₃BiZn_0.5Zr_0.5O₃ (BNT-BZZ) relaxor ferroelectrics. A win-win situation of breakdown strength and polarization is achieved in the Mn: BNT-BNZ/BNT-BZZ multilayer film with the stacking period N = 3, of which energy density and efficiency reach 80.4 J/cm³ and 62.0% respectively. It is proposed that the excellent energy storage performances are attributed to the synergistic effect of the electric field amplification effect, interface blocking effect and the polarization coupling effect based on the multilayer heterostructure. Moreover, the flexible ferroelectric film exhibits outstanding temperature (25–205 ℃), frequency (0.5–5 kHz) stability and antifatigue property (1 × 10⁸ cycles), and can well maintain stable performance at different tensile/compressive bending radii (10–5 mm) and even after 10⁴ bending cycles with a fixed bending radius of 3 mm. This work opens up a promising route to the development of flexible energy storage materials.