Interfacial Ion Transport in Porous Polydimethylsiloxane–Polydopamine Composites for Solar Thermoelectric Conversion

Abstract

Recent developments in iontronic materials and devices highlight the importance of efficient ion conduction in optimizing their performance. In particular, improving ion transport in polymer electrolytes is key to the progress of advanced energy conversion systems. This study presents a novel approach to enhance the ion conductivity of poly(ethylene oxide) (PEO)–NaOH electrolytes within porous polydimethylsiloxane (PDMS) composites. By coating PDMS with a thin layer of polydopamine (PDA) and filling it with PEO–NaOH, numerous hopping sites are generated at the PEO-PDA interface for efficient Na⁺ transport, thereby improving ion conductivity. Additionally, by combining the broadband absorption of PDA with the scattering properties of porous PDMS, the ability of the PDA–PDMS composite to efficiently absorb and convert solar radiation into heat is demonstrated. The generated heat is confined to the light-exposed region due to the thermal insulation provided by the porous PDMS. This confinement creates a temperature gradient across the composite, preferentially enhancing the thermal diffusion of Na⁺ cations over OH⁻ anions to generate thermoelectric voltage. This unique property allows for the direct conversion of solar energy into electrical energy, offering new possibilities for sustainable and efficient energy technologies.