First development of transparent wood-based triboelectric nanogenerator (TW-TENG): Cooperative incorporation of transparency, aesthetic of wood, and superior triboelectric properties

The combination of triboelectric nanogenerator (TENG) and wood-based materials offers a sustainable strategy for energy harvesting. The main challenge in realizing wood-based TENG is to increase the polarizabilities of wood. Herein, we introduce the first instance of a transparent wood-based triboelectric nanogenerator (TW-TENG), which synergistically incorporates superior triboelectric properties, optical properties, and aesthetic of wood. Addressing the challenges of weak polarizability and opacity inherent in natural wood, we propose a functionalized modification approach involving delignification and impregnation with UV-curable resin. In this study, leveraging delignification and the strong electron-donating groups within the UV-curable resin, the electrical output performance of TW-TENG is improved by 6.5 times compared to that of natural wood, and maintains stability over 10,000 operational cycles. Moreover, the matching refractive index between the UV-curable resin and the wood substrate offers TW-TENG with high transparency, achieving an optical transmittance of up to 88.8 %, exhibiting the unique aesthetic value of transparent wood. Furthermore, we demonstrate the potential applications of TW-TENG in energy harvesting, sensor technologies, smart decorative materials, smart home systems, and beyond, exemplified through its utilization in electrical output generation by pressing, capacitor charging and discharging, and self-powered multiplexed sensing smart target shooter.