Electrochemically modulated photodoping in polymeric semiconductors for efficient photo-thermoelectric conversion

Abstract

Photodoping represents a promising approach to modulate the thermoelectric conversion of organic materials. However, the relatively low photodoping level of polymeric semiconductors emerges as a critical bottleneck restricting the pace of development in this area. In this study, to address the challenges and advance the photo-modulated thermoelectric properties in polymers, we introduce an electrochemical coupling strategy toward improving the photodoping capacity by employing an electrochemical transistor geometry. The spectroscopy and electrical characterization reveals that the electrolyte ions significantly promote exciton dissociation. By combining this effect with density of states regulation via polymer blending, we achieve optimum thermoelectric properties of the polymer in the photoexcited state, with a maximum photo-thermoelectric power factor of up to 126.30 ± 25.23 µW m⁻¹ K⁻². This work not only provides fundamental insights into the electrolyte ion-gated photodoping mechanism, but also paves the way for developing high-performance polymeric photo-thermoelectric materials and devices.