Strongly enhanced and tunable photovoltaic effect in ferroelectric-paraelectric superlattices

Ever since the first observation of a photovoltaic effect in ferroelectric BaTiO(3), studies have been devoted to analyze this effect, but only a few attempted to engineer an enhancement. In conjunction, the steep progress in thin-film fabrication has opened up a plethora of previously unexplored avenues to tune and enhance material properties via growth in the form of superlattices. In this work, we present a strategy wherein sandwiching a ferroelectric BaTiO(3) in between paraelectric SrTiO(3) and CaTiO(3) in a superlattice form results in a strong and tunable enhancement in photocurrent. Comparison with BaTiO(3) of similar thickness shows the photocurrent in the superlattice is 10(3) times higher, despite a nearly two-thirds reduction in the volume of BaTiO(3). The enhancement can be tuned by the periodicity of the superlattice, and persists under 1.5 AM irradiation. Systematic investigations highlight the critical role of large dielectric permittivity and lowered bandgap.