Flexible n-type thermoelectric films based on Cu-doped Bi2Se3 nanoplate and Polyvinylidene Fluoride composite with decoupled Seebeck coefficient and electrical conductivity

We report on the fabrication of flexible and freestanding n-type thermoelectric Cu intercalated Bi2Se3 nanoplatelet/Polyvinylidene Fluoride (PVDF) composite films. The optimized power factor and figure of merit (ZT) of the Cu0.1Bi2Se3 nanoplatelet/PVDF composites are 103 μW m−1 K−2 and 0.10 at 290 K, respectively, which are one of the highest values for n-type thermoelectric films. The mechanism by which the Seebeck coefficient and electrical conductivity can be partially decoupled is explained in details: PVDF can not only grantee the robust and flexibility but also create a high trap-state by introducing the energy barrier at the organic/inorganic interface, thus a high level of Seebeck coefficient is maintained for the composite system while a remarkable improvement on electrical conductivity was achieved. The thermoelectric films show high mechanical durability with only a 13% decrease in performance after 5000 bending cycles (bending curvature 1/2 mm−1). The overall performance of the n-type thermoelectric films approaches the values required for efficient flexible thermoelectric power generators.