Stable photovoltaic output and optically tunable resistive switching in all-inorganic flexible ferroelectric thin film with self-polarization characteristic

The immense potential of photo-electrical materials applied in intelligent and wearable electronic devices has motivated many researches on flexible ferroelectric thin film. However, how to enhance stability of output and achieve multifunction is still a challenge. Here, an all-inorganic flexible ferroelectric thin film with Au/Bi₂FeMo_0.7Ni_0.3O₆/LaNiO₃/Nickel foil structure is prepared by sol-gel method. The thin film exhibits excellent photovoltaic stability. The change rates of the short circuit currents and open circuit voltages are less than 5% in different bending states and after bending-releasing cycles, which is attributed to its stable self-polarization characteristic. Furthermore, an optically tunable resistive switching behavior is found in the thin film. The switching voltages and ON/OFF ratio of resistance can be tuned in real time by on-off control of light, demonstrating a correlation between resistive switching and photovoltaic effect. It is proposed that the photovoltaic effect modulates the energy band structure of the thin film, leading to an increased ON/OFF ratio of resistance. This work opens up a promising route to the development of multifunctional flexible photo-electrical materials.