Regulation of Photovoltaic Response in ZSO-Based Multiferroic BFCO/BFCNT Heterojunction Photoelectrodes via Magnetization and Polarization

Multiferroic devices have attracted renewed attention in applications of photovoltaic devices for their efficient carrier separation driven by internal polarization, magnetization, and above-bandgap generated photovoltages. In this work, Zn₂SnO₄-based multiferroic Bi₆Fe_1.6Co_0.2Ni_0.2Ti₃O₁₈/Bi₂FeCrO₆ (BFCNT/BFCO) heterojunction photoelectrodes were fabricated. Structural and optical analyses showed that the bandgap of the spinel Zn₂SnO₄ is ∼3.1 eV while those of Aurivillius-type BFCNT and double-perovskite BFCO are 1.62 and 1.74 eV, respectively. Under the simulated AM 1.5G illumination, the as-prepared photoelectrodes delivered a photoconversion efficiency (η) of 3.40% with a short-circuit current density (J_sc), open-circuit voltage (V_oc), and fill factor (FF) of 10.3 mA·cm^–2, 0.66 V, and 50.4%, respectively. Analyses of adjustment of an applied electric and magnetic field on photovoltaic properties indicated that both magnetization and polarization of multiferroics can effectively tune the built-in electric field and the transport of charge carriers, providing a new idea for the design of future high-performance multiferroic oxide photovoltaic devices.