Three-dimensional polydimethylsiloxane/barium titanate elastomer networks for piezoelectric energy harvesters

Piezoelectric energy harvesters (PEHs) have attracted considerable attention in fields such as energy harvesting and motion monitoring due to their high electromechanical conversion capabilities. Conventionally, PEHs are obtained by dispersing piezoelectric nanofillers in a polymer matrix to achieve piezoelectric output and flexibility. However, the limited internal stress transmission results in a low piezoelectric performance, failing to meet application demands. Herein, a three-dimensional (3D) barium titanate (BT) ceramic framework is successfully prepared by pine wood-assisted sol-gel synthesis, and then composited with polydimethylsiloxane (PDMS) to form elastomer PEHs. In order to solve the low mass loading of BT due to the limited solubility of the precursors in the sol-gel, the presynthesized BT nanoparticles (NPs) are introduced into the sol-gel solution. The interconnected 3D PDMS/BT networks are found to facilitate the transmission of load along the BT framework and thereby give a large piezoelectric response. The PEH with 75% BT NPs achieves the optimal electromechanical conversion performance, with an open-circuit voltage (V_OC) of 86.6 V, a short-circuit current (I_SC) of 17.3 μA, and the maximum output power density of 39.98 μW cm⁻² with loading an external resistance of 10 MΩ. This work provides a new approach to develop 3D piezoelectric elastomer networks with a high output performance and extends applications for self-powered devices.