Feasible tuning of barrier energy in PEDOT:PSS/Bi2Te3 nanowires-based thermoelectric nanocomposite thin films through polar solvent vapor annealing

For next-generation energy harvesting thermoelectric (TE) devices based on organic/inorganic composites, the barrier energy at interfaces of components is critical in determining the TE performances, because the barrier energy can directly enhance Seebeck coefficient (S). We have succeeded in precisely tuning the barrier energy in poly (3,4-ethylene dioxythiophene) polystyrene sulfonate (PEDOT:PSS)/Bi2Te3 nanowires (NWs) based organic/inorganic nanocomposite films through polar solvent vapor annealing (PSVA). Controlling the PSS/PEDOT ratio as a function of PSVA duration, the work function of PEDOT:PSS was tuned, which eventually varied the barrier energy of nanocomposite thin films. Through optimization of Bi2Te3/PEDOT:PSS barrier energy, the S was maximized up to 47 μV/K. The electrical conductivity was also maximized simultaneously, because of the PSVA-induced π-π stacking among PEDOT chains and templating effect. Density functional theory calculated an optimal barrier energy (0.12 eV), which showed an excellent agreement with our experimentally determined optimal barrier energy (0.11 eV), at which we also maximized the power factor—an efficiency indicator of TE performance. Our feasible strategy on the manipulation of barrier energy in PEDOT:PSS/Bi2Te3 NWs through the PSVA can be extended to other organic/inorganic based TE composites, toward the realization of highly efficient TE devices.