The synergistic effect of hole co-doping on carrier transports and phonon tuning in Sb2Te3 flexible thermoelectric thin film

Abstract

Sb2Te3 thermoelectric thin film is one of the best competitive candidates for preparing self-powered wearable micro-electronic devices. However, the interdependent relationship between Seebeck coefficient, electrical conductivity and thermal conductivity limits the improvement of thermoelectric properties. In this work, we demonstrate maximum power factor of 21.06 μWcm−1K−2 and a high average power factor of 18.77 μWcm−1K−2 in (Bi, In) co-doped Sb2Te3 flexible thin film. The high power factor is ascribed to the increase in effective mass and state density after Bi doping proved by first-principles calculations and experiments, which leads to an increase in the Seebeck coefficient. Further In co-doping can increase the carrier concentration, which not only improve the electrical conductivity, but also suppress the bipolar excitation and inhibit carrier migration in the opposite direction. Moreover, the estimated thermal conductivity for the prepared thin films is low due to the enhancement of phonon scattering caused by the introduction of interfaces and defects, resulting in high ZT. A flexible device prepared by co-doped thin film represents the competitive power density of ∼ 5.47 × 102 μWcm−2 at temperature difference of 36 K. All the results confirm that hole co-doping strategy can efficiently enhance the collaborative regulations of the carrier and phonon transportation to realize high thermoelectric performance in Sb2Te3 flexible thin film.