The Cross‐Linking Effect on the Thermoelectric Properties of Conjugated Polymer/Carbon Nanotube Composite Films

摘要

Abstract Composite insulating organic material with conducting inorganic nanomaterial is a promising way to compensate the electrical conductivity, which is a prerequisite for the practical realization of the organic thermoelectrics. It is demonstrated that organic–inorganic interfacial interactions play critical rules for composites' thermoelectric performance. Here, an alternative interfacial engineering approach is proposed; that is, post‐blending cross‐linking of conjugated polymers (CPs). CPs substituted by exo‐olefin side chains that can form covalent cross‐linking via ruthenium‐catalyzed olefin metathesis are newly designed and synthesized. Pre‐cross‐link CP/single‐walled carbon nanotube (SWCNT) composites exhibit relatively high power factor that reach up to 70.3 μW m ?1 K ?2 . It is found that the cross‐linking process, using second generation Grubbs reagent, is detrimental to the thermoelectric performance. Cross‐linked composites exhibit much lower power factor (0.77–19.7 μW m ?1 K ?2 ) mainly due to the low electric conductivity of the samples, while there is no significant change in Seebeck coefficient. It may be because the formation of tightly cross‐linked network hinders the transport of carriers in CP/SWCNT, resulting in a significant decrease in the electric conductivity. These structure–property relationship studies provide useful guidelines for designing organic thermoelectric materials with performance improvement and applied green processing.