Narrow bandgap ferroelectric [KNbO3](1-x)-[BaCo1/2Nb1/2O3-δ]x solid solution for bulk photovoltaic cell

Abstract

We report a stable bulk photovoltaic effect in [KNbO3]0.9-[BaCo1/2Nb1/2O3–δ]0.1 (KBCNO-91) solid solution as a result of the light-induced electric field in the orthorhombic phase of KBCNO. Introducing Ba2+ and Co3+ ions in the host lattice of perovskite solid solution, the bandgap can be tuned from 3.2 to 1.59 eV. A photovoltaic cell consists of a 43 nm thin KBCNO-91 perovskite oxide semiconductor sandwiched between the metal electrodes evoke open-circuit voltage (VOC) of >1.9 V, above the bandgap with short-circuit current of ∼1 nA at no external bias (0 V). The fabrication of a two-dimensional ferroelectric solid solution semiconductor with a narrow bandgap of ∼1.59 eV enables the conversion of visible photons into electrical energy in a compact electrode configuration. The device retains its stability for over one year and is expected to be a potential candidate for the next generation of photovoltaic cells.