Photovoltaic Behaviors Regulated by Band-Gap and Bipolar Electrical Cycling in Holmium-Doped Bi₅Ti₃FeO₁₅ Ferroelectric Films

Abstract

The pure and Ho-doped Bi5Ti3FeO15 ferroelectric films with layered perovskite structure were prepared via a chemical solution deposition. One investigated the regulation of band gap and bipolar electrical cycling on photovoltaic behaviors including photovoltaic spectral response, open-circuit voltage, and short-circuit current for the films. It is shown that the photovoltaic response peak of Ho-doped Bi5Ti3FeO15 films shifts toward the visible region and the open-circuit voltage as well as short-circuit current are improved compared with the pure Bi5Ti3FeO15 films, which is attributed to the narrowed band gap after doping with Ho. And the spectral response, open-circuit voltage as well as short-circuit current of Ho-doped Bi5Ti3FeO15 films do not suffer from the fatigue like the pure Bi5Ti3FeO15 films with the action of bipolar electrical cycling. It just appears extended response peak without blue shift from the visible region. Likewise, Ho-doped Bi5Ti3FeO15 films still enjoy strong open-circuit voltage and short-circuit current even undergoing long period switching. Such antifatigue photovoltaic behaviors derive from the antifatigue ferroelectric, dielectric properties under illumination for Ho-doped Bi5Ti3FeO15 films. Thus, regulation of band gap and bipolar electrical cycling on the photovoltaic behaviors of ferroelectrics promotes their potential application in film solar cells.