All-Solution-Processed Transparent Electrodes Consisting of Ag NW/PEDOT:PSS Composites on PVDF-HFP Flexible Substrates for 2.5V-Operating Wearable Heaters

Abstract

Flexible transparent electrodes with mechanical flexibility have attracted increased interest as next-generation wearable heaters. In this study, a high-performance wearable transparent heater capable of 2.5V operation is demonstrated by depositing a Ag nanowire (NW)/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) composite-based heating layer on a flexible poly(vinylidene fluoride–hexafluoropropylene) substrate via an all-solution process. The effects of the concentrations of dimethyl sulfoxide and ZonylTM FS-300, a nonionic fluorosurfactant composed of a perfluoroalkyl tail linked to a polyethylene oxide chain, on the sheet resistance and heating performance of the PEDOT:PSS film were investigated, with the optimized film demonstrating a low sheet resistance of 5.4 Ω/sq. Owing to its improved electrical conductivity, the proposed wearable heater exhibited outstanding heating behavior, reaching a temperature of 74 °C at a low applied voltage of 2.5 V. Furthermore, owing to its optimized material design, the heater exhibited highly stable heating performance during long-term operation for up to 30 d under high-humidity (~90%) conditions and after repeated bending with a minimum bending radius of 5 mm. The practical heating applications of the proposed wearable transparent electrodes were demonstrated by conformal attachment to clothing and an eyeglass lens. This work provides an effective platform for low-voltage, flexible, and transparent heating applications, offering strong potential for integration into wearable and portable electronic systems.