Bioderived and all-solution-processed tribolayer component enables adaptive design of flexible nanocellulosic triboelectric nanogenerators

Abstract

Triboelectric nanogenerators (TENGs) are emerging as key enablers for self-powered and wearable electronics, yet most state-of-the-art designs still rely on thick synthetic polymers and metal foils, which add bulk, limit flexibility, and complicate end-of-life disposal. Here, we report an all-solution-processed, polysaccharide-based TENG that combines an ultrathin nanocellulose (NC) tribolayer with a graphene electrode integrated on a flexible agar substrate. The entire active stack, fabricated in situ via continuous spray coating, measures approximately 10 micrometer in thickness, yielding a lightweight, mechanically stable, and conformable TENG platform. Various chemically and mechanically tailored cellulose nanomaterials are employed and systematically screened to maximize triboelectric output. Among the NC variants explored, never-dried cellulose nanocrystals (NDCNC) delivered the strongest performance, generating an open-circuit voltage of approximately 1070 V and a peak power density of 5.76 Wm⁻², values that outperform most natural-material-based TENGs reported to date. Moreover, relative to conventional TENGs with NC tribolayers that employ metal adhesive electrodes on synthetic substrates, our design achieved a three-fold boost in voltage output. The proposed NC-graphene-agar architecture is degradable as well as adaptable to a range of device layouts without requiring re-engineering of the underlying materials stack. The tribolayer is configured as a double-electrode TENG for high-output harvesting, and a single-electrode or zero-gap TENG for compact form factors. When integrated with the human body, the TENGs are able to harvest biomechanical motion and conduct real-time touch sensing. This adaptive design strategy enables application-specific customization while preserving the high-performance capabilities of the proposed TENG.