Synergistic engineering of atomic disorder and porous architectures for ultralow lattice thermal conductivity and enhanced thermoelectric performance in n-type high-entropy lead chalcogenides

Abstract

The inherent conflict between reducing lattice thermal conductivity (κ_lat) and enhancing charge carrier transport properties poses a persistent challenge in thermoelectric material optimization, exacerbated by the complex interplay of strong electron–phonon coupling. In this work, we present a multiscale synergistic regulation strategy based on entropy engineering that markedly improves the weighted mobility-to-κ_lat ratio in n-type PbSe-based materials. Entropy-induced severe lattice distortion generates extensive strain fields, which, in concert with the intragranular microvoids, strongly scatter phonons and suppress κ_lat to its theoretical amorphous limit. Simultaneously, Br incorporation into the anion sublattice fine-tunes the carrier concentration while preserving high mobility. These synergistic effects yield a peak zT of 1.42 for the n-type PbSe system, and a 7-pair device fabricated from the optimized material achieves a power generation efficiency of ∼6.7% under a temperature difference of 470 K. This work establishes a novel design paradigm for advanced thermoelectrics through multiscale structural optimization.