Enhanced thermoelectric performance of Bi2Te3 based graphene nanocomposites

Abstract

Graphene in different vol% ranging from 0.5, 0.75 and 1.5 were uniformly incorporated in the nanostructured Bi2Te3 that was obtained from ball milling the coarse powder. The composite and the pristine Bi2Te3 powders were consolidated by the high frequency induction heated sintering. The thermoelectric properties of the bulks were investigated in the temperature range from 300 to 525 K. The effective thermal conductivities of the composites decrease with the reduction in the particle size of the pristine Bi2Te3 as well as with the addition of graphene attributed to enhanced phonon scattering from the phase boundaries. The significant increase in electrical conductivity accompanied by less decrease in the Seebeck coefficient at 1.5 vol% of graphene culminates in a high power factor. The results suggest that enhancement in power factor is attributed to quantum confinement effect through introduction of 2D graphene in Bi2Te3. Thus, reduction in thermal conductivity in conjunction with substantial improvement in power factor at 1.5 vol% of graphene leads to considerable enhancement in the thermoelectric figure of merit at ∼500 K from pristine bulk. This work presents a novel strategy for development of high performance cost effective and scalable nanostructured thermoelectric bulk materials similar to Bi2Te3 based superlattices.