Achieving Free-Standing PEDOT:PSS Solar Generators with Efficient All-in-One Photothermoelectric Conversion

Poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) has attracted widespread attention in solar generation due to its unique all-in-one photothermoelectric effect. However, the poor photothermal conversion, low conductivity, and unsatisfied mechanical properties limit its practical application. Herein, ionic liquids (IL) were first used to improve the conductivity of PEDOT:PSS through ion exchange, then surface-charged nanoparticles SiO₂-NH₂ (SiO₂⁺) were added to promote the dispersion of IL and as a thermal insulator to decrease thermal conductivity. It resulted in a largely enhanced electrical conductivity and decreased thermal conductivity of PEDOT:PSS simultaneously. The obtained PEDOT:PSS/Ionic Liquid/SiO₂⁺ (P_IL_SiO₂⁺) film generated an excellent photothermal conversion of 46.15 °C, which improved ∼134 and ∼82.3% compared with PEDOT:PSS and PEDOT:PSS/Ionic Liquid (P_IL) composites, respectively. In addition, the thermoelectric performance increased by ∼270% more than P_IL films. As a result, the photothermoelectric effect for the self-supported three-arm devices produced an enormous output current and power of ∼50 μA and 13.57 nW, respectively, which showed significant improvement compared with other PEDOT:PSS films reported in the literature. Furthermore, the devices demonstrated outstanding stability with an internal resistance variation of less than 5% after 2000 cycles of bending. Our research offered significant insights into the flexible, high-performance, all-in-one photothermoelectric integration.