Photocurrent density and electrical properties of Bi_0.5Na_0.5TiO₃-BaNi_0.5Nb_0.5O₃ ceramics

In this work, the (1-x)Bi_0.5Na_0.5TiO₃-xBaNi_0.5Nb_0.5O₃ (BNT-BNN; 0.00 ≤ x ≤ 0.20) ceramics were prepared via a high-temperature solid-state method. The crystalline structures, photovoltaic effect, and electrical properties of the ceramics were investigated. According to X-ray diffraction, the system shows a single perovskite structure. The samples show the normal ferroelectric loops. With the increase of BNN content, the remnant polarization (P_r) and coercive field (E_c) decrease gradually. The optical band gap of the samples narrows from 3.10 to 2.27 eV. The conductive species of grains and grain boundaries in the ceramics are ascribed to the double ionized oxygen vacancies. The open-circuit voltage (V_oc) of ~15.7 V and short-circuit current (J_sc) of ~1450 nA/cm² are obtained in the 0.95BNT-0.05BNN ceramic under 1 sun illumination (AM1.5G, 100 mW/cm²). A larger V_oc of 23 V and a higher J_sc of 5500 nA/cm² are achieved at the poling field of 60 kV/cm under the same light conditions. The study shows this system has great application prospects in the photovoltaic field.