Microstructures and photovoltaic effect of Ba/Fe modified Bi0.5Na0.5TiO3 ferroelectric ceramics

Oxide ferroelectrics have great potential applications in optoelectronic and solar devices. However, most oxide ferroelectrics show wide bandgaps (>3.2 eV), limiting their use in the photovoltaic field. Adding BaFeO3 (BF) into the ferroelectric Bi0.5Na0.5TiO3 (BNT) matrix decreases the bandgap and enhances the photocurrent densities. This work prepares perovskite-structured (1 − x) Bi0.5Na0.5TiO3–xBaFeO3 (BNT–BF; x = 0.00–0.10) ceramics via the solid-state reaction. Increasing BF content reduces the rhombohedral distortion and weakens the ferroelectric ordering. The optical bandgap of the ceramics decreases from 3.10 eV (x = 0.00) to 1.70 eV (x = 0.10). The open-circuit voltage (Voc) and short-circuit current (Jsc) of the 0.95BNT–0.05BF sample under the illumination of simulated standard sunlight (AM 1.5, 100 mW/cm2) are 18.9 V and 1.75 μA/cm2, respectively. Significant improvements of Jsc = 3.85 μA/cm2 and Voc = 23.85 V, poled at 20 kV/cm, are achieved. The good performance of the BNT-BF demonstrates its excellent potential for applications in photovoltaics.