High-performance in n-type PbTe-based thermoelectric materials achieved by synergistically dynamic doping and energy filtering

The development of n-type high-performance PbTe thermoelectric materials for matching its p-type counterparts is an urgent matter to expand its practical applications. Here, we introduce Ag2Te into n-type Pb0.975Cr0.025Te for achieving a high peak figure of merit of 1.5 at 773 K. Such a high value is attributed to the synergistic optimization of carrier and phonon transports by Ag2Te introducing and the dynamic doping of Ag. From the detailed structure and property analysis, we found that Ag2Te nanoprecipitates establish coherent interfaces and hence potential barriers with the matrix to induce energy-dependent carrier scattering and maintain relatively high carrier mobility, leading to an optimal electrical-transport properties over a wide temperature range. Moreover, we employ comprehensive electron microscopy investigations and approximate Debye-Callaway model to reveal the origin of the significantly reduced lattice thermal conductivity in Ag2Te-alloyed Pb0.975Cr0.025Te. The strategies used here provide an effective method for designing high-performance thermoelectric material systems.