Flexible PiezoelectricNanogenerators Based on Sono-ChemicallyExfoliated MoSe₂–PVDF Nanocomposites for EfficientEnergy Harvesting

The pursuit for efficient piezoelectric nanogenerators (PENGs) for mechanical energy harvesting is attractive for self-powered, flexible, portable, and wearable Internet-of-Things (IoT) devices. This study presents the development of a high-performance PENG by incorporating sono-chemically exfoliated two-dimensional molybdenum diselenide (MoSe₂) nanosheets into polyvinylidene fluoride (PVDF), resulting in a nanocomposite frictional layer. Utilizing dimethylformamide (DMF) as the solvent, we achieved an optimized concentration of MoSe₂ within PVDF in a sandwich-structured configuration, leading to a significant improvement in the energy-harvesting efficiency. The device exhibited a maximum open-circuit voltage of ∼56 V and a power density of 680 μW/cm² under an applied pressure of about 15 kPa leading to a sensitivity of ∼3.73 V/kPa, revealing the potential of 2D MoSe₂ for efficient energy harvesting. Subsequent measurements demonstrated several mechanical energy harvesting sources using pen sketching, wind flow from a hand blower, and water droplets. Moreover, biomechanical activities such as wrist and elbow movements and walking produced notable output voltages, underscoring the potential of this PENG in wearable electronics, portable devices, and IoT applications. These nanogenerators could be potentially attractive for autonomous, low-maintenance energy solutions, transforming daily life activities into electrical power for consumer devices and facilitating environmental monitoring via remote sensors energized by natural vibrations.