High power-output mechanical energy harvester based on flexible and transparent Au nanoparticle-embedded polymer matrix

The blossoming of portable electronics has raised the need to develop high power devices with multifunctionality, such as transparency and flexibility. Herein, for the first time a flexible and transparent crosslinked polyethyleneimine/poly(vinyl alcohol) composite is developed for the fabrication of mechanical energy harvester. The output of the device is markedly enhanced by the introduction of Au nanoparticles (NPs) due to the increase of the composite's dielectric property. With optimal load of AuNPs, the composite based device generates highest surface charge density manifested by maximum surface potential difference. Accordingly, an open-circuit voltage of 161.1 V, a short-circuit current density of 20 mA m⁻², and a record-high peak power density of 17.73 W m⁻² (16 mW) is achieved. Meanwhile, the device exhibits stability with no significant change in output after five months. Additionally, the charge transfer mechanism involved in the contact electrification process of the investigated composite is discussed. This study successfully demonstrates a promising potential of the composite in mechanical energy harvesting and an effective pathway to boost the output power through the engineering of the bulk dielectric properties.