Enhanced thermoelectric performance of n-type PbTe through introducing PbSe by a fast preparation method

Abstract

N-type PbTe-based materials exhibit promising thermoelectric performance around 600–900 K, while the near room-temperature thermoelectric performance still needs to be improved due to their high thermal conductivity. Forming solid solutions is an effective strategy to strengthen phonon scatterings and results in lower lattice thermal conductivity. However, the existing preparation methods used in PbTe-based solid solutions are time-consuming and energy-intensive, which limits their further applications. Herein, we report a fast method combined self-propagating high-temperature synthesis (SHS) with spark plasma sintering (SPS) to successfully fabricate PbTe–PbSe solid solutions. Due to the mass and strain fluctuations, a largely reduced room temperature lattice thermal conductivity of 1.27 W m−1 K−1 was achieved in (Pb0.995Bi0.005Te)0.8-(PbSe)0.2, which was 40% lower than that of pristine Pb0.995Bi0.005Te. Besides, carrier mobility increased after PbSe alloying, leading to comparable electrical performance. Consequently, a maximum average thermoelectric figure of merit ZTave reached 0.57 at 300–623 K of (Pb0.995Bi0.005Te)0.8-(PbSe)0.2 and was 21% and 24% higher than those of pristine Pb0.995Bi0.005Te and PbSe, respectively. Such a simple and effective method is expected to be further adopted in other thermoelectric solid solutions.