One-step interfacial synthesis and thermoelectric properties of Ag/Cu-poly(3,4-ethylenedioxythiophene) nanostructured composites

Abstract

Ag-poly(3,4-ethylenedioxythiophene) (PEDOT) and Cu–PEDOT nanocomposites have been synthesized by an interfacial polymerization method, using 3,4-ethylenedioxythiophene (EDOT) and AgNO₃ or Cu(NO₃)₂ as starting materials. Ag–PEDOT or Cu–PEDOT nanocomposites prepared at an interface of n-hexane and acetonitrile are spherical Ag- or Cu- nanoparticle (0D)-modified PEDOT nanostructures, while a Cu–PEDOT nanocomposite prepared at an interface of n-hexane and a mixture of acetonitrile and glycol exhibits a different morphology: Cu nanostructures are needle-like (1D) and embedded in a PEDOT matrix. Ag- or Cu-nanoparticle contents in the composites can be tuned by changing oxidant (AgNO₃ or Cu(NO₃)₂)/EDOT molar ratios, and thermoelectric properties of the pellets cold pressed from composite powders with different Ag or Cu contents have been measured at room temperature. When the oxidant/EDOT molar ratio is 2, both Ag–PEDOT and Cu–PEDOT nanocomposites with spherical Cu nanoparticles reach their largest power factors of 1.49 and 7.07 μW m⁻¹ K⁻², respectively, while Cu–PEDOT nanocomposite with needle-like Cu nanoparticles has consistently higher power factor than the above composites. When the oxidant/EDOT molar ratio is 1, it reaches its largest power factor of 12.47 μW m⁻¹ K⁻² and the highest ZT value of 0.01 at room temperature.