Distinguishable Separation of Artificial Electron–Oxygen Vacancy Pairs Using Heterovalent Doping Effect for Ferroelectric Photovoltaics

Abstract

Artificial electron–oxygen vacancy pairs were fabricated by heterovalent Mn doping in the Na0.5Bi4.5Ti4O15 parent phase, which offers an excellent platform for studying oxygen vacancy physics. In view of its excellent photovoltaic performance, the phase structure, morphology, and ferroelectric polarization were investigated. Moreover, using heterovalent Mn doping in Na0.5Bi4.5Ti4O15 films as a model system, we demonstrate that the effective separation of artificial electron–oxygen vacancy pairs by an electric field and illumination can be used to enhance photovoltaics. Specifically, we clarified the contribution of artificial electron-vacancy pairs using photocurrent measurements. Furthermore, the enhanced reversible photocurrent is dependent on the doping level and polarization. The present investigation suggests that heterovalent Mn doping opens up the prospective technology of artificial electron–oxygen vacancy pairs in ferroelectric cells.