High-performance n-type Ta4SiTe4/polyvinylidene fluoride (PVDF)/graphdiyne organic-inorganic flexible thermoelectric composites

In the past decade, the development of high-performance p-type flexible organic-inorganic thermoelectric composites based on nanocarbons (e.g. carbon nanotubes and graphene) has achieved unprecedented success, but the progress in n-type counterpart lags much behind because carbon nanotubes and graphene usually demonstrate p-type behavior. In this work, beyond carbon nanotubes and graphene, we conduct a proof-of-principle study by using semiconducting graphdiyne (GDY) to fabricate high-performance n-type organic-inorganic flexible thermoelectric composites. Based on the chemical interactions between GDY and quasi one-dimensional semiconductor Ta4SiTe4, we successfully fabricate the n-type Ta4SiTe4/polyvinylidene fluoride (PVDF)/GDY composite films. GDY is homogeneously distributed inside the composites, acting as bridges among the Ta4SiTe4 whiskers to significantly improve the electrical conductivity. Combining the well-maintained large Seebeck coefficient and low thermal conductivity, Ta4SiTe4/PVDF/GDY composite films demonstrate a maximum ZT of 0.2 at 300 K, among the highest values reported in organic-inorganic flexible thermoelectric composites. The protype thermoelectric module consisting of n-type Ta4SiTe4/PVDF/GDY legs and p-type PEDOT:PSS/CNT legs shows the highest normalized maximum power density among the reported flexible organic materials-based flexible TE modules including both n- and p-type legs.