Chemically Functionalized High Performance Lead Free Piezoelectric Nanogenerator for Flexible Electronics

Organic-inorganic lead based metal halide perovskites have recently emerged as promising candidates for energy harvesting, solar cells, and wearable electronic because of their superior performance. But due to the toxicity of lead, recently lead-free flexible piezoelectric nanogenerator (PENGs) have drawn much attention. Here, we reported lead free PENG, which is a combination of formamidinium tin (Sn) halide perovskite and polyvinylidene fluoride (PVDF) as soft polymer matrix. However, as the Sn 2+ is easily oxidized to Sn 4+ and leads to self-doping in ambient air which results in poor stability and reproducibility, we improved the air stability by using the most common additive SnF2. The morphology study via X-ray diffraction pattern (XRD) of the FASnBr3@SnF2 doped and without doping clearly demonstrated that the characteristic peaks of SnO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> at 25.2°, and 51.8° are eliminated due to the doping of SnF2 which indicates the stability improvement of the fabricated film. By using the atomic force microscopy (AFM) in PFM mode, we confirm the piezoelectric properties of the FASnBr3@PVDF NPs. With the outstanding flexibility and homogeneous distribution, the device showed a maximum piezoelectric peak to peak output voltage of 84.5 Vp-p, and able to charge a capacitor of 4.7 μF up to 10 V within 30 seconds with only a force of 4.2 N. This study demonstrates the great potential of chemically engineered stable lead-free materials in next-generation high-performance PENG applications.