Modulating crystallinity and dielectric constant of chitosan film for triboelectric polarity shift and performance enhancement in triboelectric nanogenerators

Triboelectric nanogenerators hold great promise as a sustainable energy solution, with natural biopolymers offering eco-friendly options for their development. However, biopolymers often exhibit lower triboelectric properties than synthetic polymers. Herein, a novel strategy is proposed to modulate the triboelectric polarity and enhance the performance of chitosan films by manipulating their crystallinity and incorporating single-walled carbon nanotubes. It was found that the crystalline structure changed the electron affinity of the surface state with molecular chain arrangement, and proper carbon nanotubes improved the dielectric properties and the balance with the leakage current effect. Through the modulation of crystallinity and nanofillers, various triboelectric properties can be achieved theoretically. Consequently, the charge density of the optimized performance reached 262 mu C m(-2), 2.45 times that of the pure chitosan film. Furthermore, the device presents longterm triboelectric output stability in the humidity range of 20-85%. In addition to serving for energy harvesting, a potential application as a waist-wearable respiration sensor for running was further developed. This work provides a promising strategy for improving the triboelectric performance of chitosan and expanding its potential applications.