High-Performance Ag2Se/Methyl Cellulose Thermoelectric Composites for Flexible Power Generators

Abstract

Flexible thermoelectric generators (FTEGs) offer a promising solution for powering wearable electronics, while their practical applications are mainly obstructed by the moderate properties of flexible thermoelectric (TE) materials. Here, flexible Ag2Se nanowire (NW)/methyl cellulose (MC) composite films were developed via facile screen-printing technology combined with cold pressing and annealing treatment, and a highest power factor of 1,641.58 μW m−1 K−2 at 360 K was achieved. The reasons for the high TE performance of the Ag2Se NW/MC composite films were because, after the annealing treatment, the Ag2Se NWs were sintered to form conductive network structures, the crystallinity of Ag2Se was markedly enhanced, and the content of insulating phase MC in the composite film was decreased. The Ag2Se NW/MC composite film held appreciable flexibility, as its room-temperature power factor (1,312.08 μW m−1 K−2) can retain ~93% after bending for 1,000 cycles at a radius of 4 mm. Furthermore, the assembled FTEG consisting of 4 strips can generate a maximal power density of 3.51 W m−2 at a temperature difference of 14.1 K. Our results open an effective and large-scale strategy for fabricating high-performance flexible TE materials and energy-harvesting devices.