Step towards High Power Factor in Acidic-Doped Poly(3-hexylthiophene) Systems

In this study, we present dodecylbenzenesulfonic acid (DBSA) as a cost-effective alternative to F4TCNQ for doping poly-(3-hexylthiophene) (P3HT). DBSA not only acts as a p-type dopant but also serves as a surfactant, influencing the material's morphology and electronic properties. We investigated the impact of dopant concentration (ranging from 0.0001% to 20% v/v) on electrical conductivity, Seebeck coefficient, and power factor in spin-coated thin films. Seebeck coefficient values ranged from 59 μV·K^-1 (at 12% v/v DBSA) to 352.9 μV·K^-1 (at 0.1% v/v DBSA), while the optimal P3HT:DBSA composition (11% v/v DBSA) exhibited a conductivity of 5.58 S·cm^-1, a Seebeck coefficient of 69.7 μV·K^-1, and a power factor of 2.706 μW·m^-1·K^-2. Atomic force microscopy (AFM) revealed that higher DBSA concentrations reduced surface roughness, influencing the conductivity. The obtained thermoelectric parameters are comparable to those of sulfuric acid and F4TCNQ-doped P3HT, highlighting DBSA as a promising and less toxic alternative for organic thermoelectrics.