Recent progress in bismuth ferrite-based thin films as a promising photovoltaic material

Application of ferroelectric oxides in photovoltaic devices has been revived by the emergence of bismuth ferrite thin films, a lead-free perovskite with a narrow bandgap (∼2.7 eV) and high remnant polarization (up to 100 µC cm−2). Ferroelectrics are known to exhibit above-bandgap photovoltage and switchable photocurrent. They may also display new functionalities if coupled with ferroic orders. Over the past few years, the research in the field of ferroelectric photovoltaic, mainly BiFeO3, has been thriving toward enhanced photovoltaic performance. The power conversion efficiency of 8.1% has been already achieved and larger values were theoretically predicted. In this context, this article summarizes prominent theories associated with ferroelectric-photovoltaic mechanism and provides the most recent progress in BiFeO3-based thin film devices. Emphasis is placed on design principles toward tailoring the photovoltaic effect via interfacial effect of electrodes and oxygen vacancies, as well as bandgap engineering. Finally, critical survey is accompanied with future perspectives, including integration of BiFeO3-based perovskites to other solar absorbers for highly efficient photovoltaic devices.