Institut Charles Sadron Event

Conjugated polymers offer great potential for organic thermoelectrics, particularly for harvesting low-grade heat in the ambient temperature range. This thesis explores the design of highly porous, thermally insulating and electrically conducting materials. They were obtained through polymer gelation, followed by supercritical drying (aerogels) or freeze-drying (cryogels). Two systems were investigated: p-type fibrillar P3HT:sPS aerogels and n-type channel-like PBFDO:PVDF cryogels. Both were doped directly in the gel state, using molecular dopants such as F4TCNQ, FeCl?, or Magic Blue for p-type, and L-PEI for n-type. Their morphology and structural organization were characterized by SEM, cryo-SEM, and WAXS/SAXS. The study shows that tuning the polymer ratio and doping conditions strongly impacts thermoelectric properties. Optimized P3HT:sPS aerogels (1:1 ratio, 95% porosity) combined ultralow thermal conductivity (28 mW.m?¹·K?¹) with electrical conductivity up to 0.05 S.cm?¹, while PEI-doped PBFDO:PVDF cryogels (4:96 ratio, >90% porosity) reached 50 mW.m?¹.K?¹ and 0.25 S.cm?¹. Under a modest temperature difference (11 K), these materials delivered power outputs up to 125 nW.cm?² for p-type and 100 nW.cm?² for n-type. Overall, this work establishes porous polymer blends as promising platforms for lightweight and efficient organic thermoelectric devices. Keywords: Organic thermoelectrics, energy harvesting, porous conducting materials, polymer blends, porous materials, , P3HT, PBFDO, structure – properties relationship.