Enhanced piezoelectric output performance via control of dielectrics in Fe2+- incorporated MAPbI(3) perovskite thin films: Flexible piezoelectric generators

We report a high-performance flexible piezoelectric generator (PEG) that was based on organic-inorganic lead halide perovskite materials and is operated by controlling the dielectric constant via the partial substitution of Pb2+ with Fe2+ in MAPbI(3). The partial replacement of Pb2+ with Fe2+ improved both the morphology and crystallinity of MAPb(1-x)Fe(x)I(3) (0.01 <= x <= 0.50) films that undergo a tetragonal-cubic phase transition above an incorporated concentration of Fe2+ (x > 0.07). In addition, the phase transition temperatures of MAPb1-xFexI3 (0.01 <= x <= 0.07) films linearly decreased as a function of incorporated concentration, which resulted in a transition temperature for MAPb(1-x)Fe(x)I(3) (x = 0.07) of similar to 45.5 +/- 1.5 degrees C. The dielectric properties as a function of incorporated concentration at room temperature suggested that MAPb(1-x)Fe(x)I(3) (x = 0.07) exhibited a dielectric constant of similar to 107 and a dissipation factor of 0.02 at 100 kHz. The MAPb(1-x)Fe(x)I(3) (x = 0.07) films exhibited a low leakage current density of similar to 10-6 at a high applied electric field of 40 kV/cm, and the resultant remanent polarization from saturated ferroelectric P-E hysteresis loops was similar to 1.6 mu C/cm(2). The MAPb(1-x)Fe(x)I(3) (x = 0.07) flexible PEG improved output performance by similar to 7.29 V and current density by similar to 0.88 mu A/cm(2) after poling at 30 kV/cm. This was sufficient to instantly light a commercial light-emitting diode (LED) without a storage device. This approach provides a framework that enhances the output performance of organic-inorganic metal halide perovskite materials-based piezoelectric energy harvesters, which could help pave the road to viable, selfpowered, wearable electronics.