The effect of temperature on thermoelectric properties of n-type Bi2Te3 nanowire/graphene layer-by-layer hybrid composites.

The thermoelectric properties of Bi2Te3 nanowire/graphene composites prepared at different sintering temperatures have been investigated. The as-synthesized ultrathin Bi2Te3 nanowires are uniformly distributed between the graphene layers, leading to the formation of Bi2Te3 nanowire/graphene layer-by-layer hybrid structures. The electrical conductivity of the as-sintered composites increases dramatically with the sintering temperature, as the relative density and grain size increase and the interface density decreases. This in turn lowers the Seebeck coefficient due to the reduction of the potential barrier for carriers and their scattering at the interface. The fabricated n-type Bi2Te3 nanowire/graphene composites exhibit an enhanced figure of merit of 0.25 at an optimal sintering temperature of 623 K.