Flexible n-Type Abundant Chalcopyrite/PEDOT:PSS/Graphene Hybrid Film for Thermoelectric Device Utilizing Low-Grade Heat.

Abstract

Combining inorganic thermoelectric (TE) materials with conductive polymers is one promising strategy to develop flexible thermoelectric (FTE) films and devices. As most inorganic materials tried up until now in FTE composites are composed of scarce or toxic elements, and n-type FTE materials are particularly desired, we combined the abundant, inexpensive, nontoxic Zn-doped chalcopyrite (Cu1-xZnxFeS2, x = 0.01, 0.02, 0.03) with a flexible electrical network constituted by poly(3,4-ethylenedioxythiophene) polystyrenesulfonate (PEDOT:PSS) and graphene for n-type FTE films. Hybrid films from the custom design of binary Cu1-xZnxFeS2/PEDOT:PSS to the optimum design of ternary Cu0.98Zn0.02FeS2/PEDOT:PSS/graphene are characterized. Compared with the binary film, a 4-fold enhancement in electrical conductivity was observed in the ternary film, leading to a maximum power factor of ∼ 23.7 μW m-1 K-2. The optimum ternary film could preserve >80% of the electrical conductivity after 2000 bending cycles, exhibiting an exceptional flexibility due to the network constructed by PEDOT:PSS and graphene. A five-leg thermoelectric prototype made of optimum films generated a voltage of 4.8 mV with a ΔT of 13 °C. Such an evolution of an inexpensive chalcopyrite-based hybrid film with outstanding flexibility exhibits the potential for cost-sensitive FTE applications.