Excellent thermoelectric cooling and power generation are simultaneously realized in an n‐type PbTe‐based thermoelectric material. The cooling temperature difference (ΔT) of ≈15.6 K, maximum power density of ≈0.4 W cm−2 and conversion efficiency of ≈1.5% with TC = 295 K and TH = 765 K can be obtained in a single‐leg device composed of PbTe‐30%SnSe‐1.5%Cu. This advanced thermoelectric performance in n‐type PbTe‐30%SnSe‐1.5%Cu mainly originates from its high‐ranged ZT value achieved through optimizing its bandgap, carrier density, and microstructure. The bandgap in PbTe is first reduced by SnSe alloying to facilitate the carrier transport properties at low temperature range (300–573 K). With further tuned carrier density, the average power factor increases from ≈10.2 µW cm−1 K−2 in Pb0.985Sb0.015Te‐30%SnSe to ≈16.2 µW cm−1 K−2 in PbTe‐30%SnSe‐1.5%Cu at 300–773 K. Moreover, microstructure observation reveals high‐density dislocations in PbTe‐30% SnSe‐1.5% Cu, which can dramatically suppress the room‐temperature lattice thermal conductivity from ≈2.21 Wm−1 K−1 in Pb0.985Sb0.015Te to ≈0.53 Wm−1 K−1 in PbTe‐30%SnSe‐1.5%Cu. As a result, a room‐temperature ZT value of ≈0.7 and high average ZT value (ZTave) of ≈0.98 can be obtained in PbTe‐30%SnSe‐1.5%Cu at 300–573 K, which makes its performance comparable to the commercial n‐type Bi2Te3‐based thermoelectric material.

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Aberration-corrected scanning transmission electron microscopy (AC-STEM) has evolved into the most powerful characterization and manufacturing platform for all materials, especially functional materials with complex structural characteristics that respond dynamically to external fields. It has become possible to directly observe and tune all kinds of defects, including those at the crucial atomic scale. In-depth understanding and technically tailoring structural defects will be of great significance for revealing the structure-performance relation of existing high-property materials, as well as for foreseeing paths to the design of high-performance materials. Insights would be gained from piezoelectrics and thermoelectrics, two representative functional materials. A general strategy is highlighted for optimizing these functional materials’ properties, namely defect engineering at the atomic scale.

Electron‐correlated materials have been drawing ever‐increasing attention due to their fascinating physical behaviors and extensive application scenarios. In this review, a new method for material research and design (R&D), named structural‐functional unit ordering (SFU ordering), which is presented, overcomes the shortcomings—for example, the limitation of finite chemical elements and long R&D circle‐of conventional strategy and thus provides guidance for the design of these high‐performance functional materials on demand. Meanwhile, with the development of material characterization technologies, SFUs of different scales and types can be directly observed, which, moreover, regulate the corresponding orderings. The review, starts with an introduction of the profile for SFU ordering and the synergistic effect between SFUs. Then, studies on several new high‐performance electronic‐correlated materials, for example, a ferromagnetic semiconductor with local spin, ferromagnetic metals with spin topologies, ferroelectric thin films with polar topologies, piezoelectric thin films with nanopillars enclosed by charged boundaries, thermoelectric materials with local ferromagnetic nanoparticles and topotactic phase transformation with conducting nanofilaments are stated in detail one by one. The vital aspect is the breaking of local symmetry, the construction, the structure, of SFUs and their orderings existing or theoretically existing, together with the enhanced/new performance. All in all, the main comments of the review tend to the remaining challenges, promising design approaches for the SFUs, and their orderings for high‐performance functional materials.