Excellent dispersion effects of carbon nanodots on the thermoelectric properties of Bi2Te2.7Se0.3 with excessive Te

Abstract

With excellent performance at room temperature as well as being the most mature n-type thermoelectric material in commercialization, Bi2Te2.7Se0.3 has been attracting increased attention. In this study, its carrier concentration and mobility were optimized by introducing excessive Te. When the excessive content of Te was 0.4, its power factor was the largest, and its thermal conductivity declined slightly. Based on Te excess, carbon nanodots were introduced as the dispersed nanosecond phase. The power factors were improved further due to the energy filter effect. In particular, the lattice thermal conductivity was depressed remarkably due to enhanced phonon scattering. Finally, at 423 K, the maximum ZT value of the sample reached 0.91, which was approximately 42% higher than that of the pure Bi2Te2.7Se0.3. The experimental results demonstrate that carbon nanodots dispersion acting as a nanosecond phase is an effective method to improve the thermoelectric performance of n-type Bi2Te2.7Se0.3-based materials.