All-solution-processed transparent electrodes consisting of Ag NW/PEDOT:PSS composites on PVDF-HFP flexible substrates for 2.5 V-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 2.5 V 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 Zonyl^TM FS-300 on the sheet resistance and heating performance of the PEDOT:PSS film are investigated, with the optimized film demonstrating a low sheet resistance of 5.4 Ω sq⁻¹. Owing to its improved electrical conductivity, the proposed wearable heater exhibits outstanding heating behavior, reaching a temperature of 74 °C at a low applied voltage of 2.5 V. Furthermore, highly stable heating performance during long-term operation for up to 30 days under high-humidity (∼90%) conditions and after repeated bending with a minimum bending radius of 5 mm is achieved. The practical heating applications of the proposed wearable transparent electrodes are 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.