Boosting thermoelectric power factor of free-standing Poly(3,4ethylenedioxythiophene):polystyrenesulphonate films by incorporation of bismuth antimony telluride nanostructures

We demonstrate that introduction of p-type Bi0.5Sb1.5Te3 nanostructures into the polymer matrix not only causes highly adherent drop-casted films of PEDOT:PSS (on Kapton sheets) to attain a free-standing nature but also brings a significant improvement in their thermoelectric properties. Hall and ESR measurements of these hybrid films clearly show that both the carrier concentration and mobility can be varied with Bi0.5Sb1.5Te3 content. Whereas, results of X-ray diffraction, Raman and X-ray photoelectron spectroscopy confirm the enhancement in chain alignment and better connectivity among PEDOT:PSS and Bi0.5Sb1.5Te3 nanosheets; leading to remarkable enhancement of electrical conductivity. These hybrid films, due to energy filtering of charge carriers at the organic/inorganic interface, exhibit improvement in the Seebeck coefficient also. In fact, such a synergetic combination of improved electrical conductivity and Seebeck coefficient expertly tailors the power factor (from order of ~10−4 to 8.3 μW/mK2) over a vast range. The optimized films are tested for their power conversion ability and a single thermoelement based device exhibits an open circuit voltage ~536 μV and current ~134 μA for a temperature difference of 53 °C. Such an evolution of organic-inorganic hybrid films in a flexible, free-standing motif with enhanced thermoelectric properties exhibit good potential for recovering heat from the curved hot surfaces.