High thermoelectric performance of n-type PbTe is urgently needed to match its p-type counterpart. Here, we show a peak ZT ∼ 1.5 at 723 K and a record high average ZT > 1.0 at 300-873 K realized in n-type PbTe by synergistically suppressing lattice thermal conductivity and enhancing carrier mobility by introducing CuTe inclusions. Cu performs several outstanding roles: Cu atoms fill the Pb vacancies and improve carrier mobility, contributing to an unexpectedly high power factor of ∼37 μW cm K at 423 K; Cu atoms filling Pb vacancies and Cu interstitials both induce local disorder and, together with nano- and microscale Cu-rich precipitates and their related strain fields, lead to a very low lattice thermal conductivity of ∼0.38 Wm K in PbTe-5.5%CuTe, approaching the theoretical minimum value of ∼0.36 Wm K. This work provides an effective strategy to enhance thermoelectric performance by simultaneously improving electrical and thermal transport properties.

Dual-site point defects formed through partially dissolved Sb nanophases contribute to distortion of density-of-states and enhancement of phonon scattering.

Synergistically optimizing the band structure and introducing point defects lead to remarkably high ZT in n-type PbTe–MnTe.

Grain or phase boundaries play a critical role in the carrier and phonon transport in bulk thermoelectric materials. Previous investigations about controlling boundaries primarily focused on the reducing grain size or forming nanoinclusions. Herein, liquid phase compaction method is first used to fabricate the Yb‐filled CoSb3 with excess Sb content, which shows the typical feature of low‐angle grain boundaries with dense dislocation arrays. Seebeck coefficients show a dramatic increase via energy filtering effect through dislocation arrays with little deterioration on the carrier mobility, which significantly enhances the power factor over a broad temperature range with a high room‐temperature value around 47 μW cm−2 K−1. Simultaneously, the lattice thermal conductivity could be further suppressed via scattering phonons via dense dislocation scattering. As a result, the highest average figure of merit ZT of ≈1.08 from 300 to 850 K could be realized, comparable to the best reported result of single or triple‐filled Skutterudites. This work clearly points out that low‐angle grain boundaries fabricated by liquid phase compaction method could concurrently optimize the electrical and thermal transport properties leading to an obvious enhancement of both power factor and ZT.

Enhanced electrical transport properties and low thermal conductivity lead to high figure of merit (ZT) over the whole temperature range in Na-doped SnS crystals.

A single phase CuSbSe2 polycrystalline chalcostibite compound has been facilely synthesized through mechanical alloying for the first time, and the phase evolution has been revealed in detail.

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An effective approach to enhance the thermoelectric performance (ZT) of polycrystalline In4Se3 based samples by crystallographic and microstructural engineering is proposed and demonstrated. Cu intercalation, Br substitution at selenium sites, and incorporation of dispersed hierarchical nanoparticles are discussed. An improved ZT of 1.1 at 723 K is achieved in CuBr2 doped In4Se2.5.