Flexible all-inorganic BiFeO₃-based film with high piezoelectric coefficient for energy harvesting and sensing

With the development of new sensor technology, flexible piezoelectric materials possessing exceptional mechanical-to-electrical energy conversion capabilities hold great promise for application in a variety of sectors, including biomedicine, flexible robotics, and wearable electronic devices. This work reports the successful growth of an all-inorganic transparent Bi(Fe_0.95Mn_0.05)O₃ (BFOMn) film on the Mica substrate using a straightforward one-step sol–gel method. The prepared BFOMn thin film enables the optimum electrical properties with a saturated polarization of ~ 92 μC/cm², a remanent polarization of ~ 74 μC/cm², and a high piezoelectric constant d₃₃ of ~ 405 pm/V. Concurrently, the film exhibits exceptional adaptability without compromising its electrical performance, as evidenced by its capacity to undergo a tight curve with a radius of just 2 mm. Utilizing this BFOMn film, the fabricated flexible piezoelectric energy harvester (FPEH) has exceptional energy collecting capabilities, producing an output voltage of 15 V, a short current of 130 nA, and a notable force sensitivity of 4 V·N⁻¹ before poling. It can also be employed to monitor human actions, such as hand hammering, hand clapping, and foot stepping. This work demonstrates the potential of the BiFeO₃-based FPEH/sensor in the field of new intelligent electronics.