Solid-state thermoelectric devices enable the conversion of waste heat and solar energy into electricity, providing an alternative route for energy harvesting to tackle the challenges of energy sustainability. α-MgAgSb-based materials have recently gained popular attention as a new promising p-type candidate for low-temperature (between room temperature and 550 K) applications. A high figure of merit (ZT) of 1.2–1.4 at 550 K was achieved, along with experimental demonstration of a record high conversion efficiency of ∼8.5% under a cold- and hot-side temperature difference of 225 K, which holds the realistic prospect for power generation. In this review, we summarize the recent progress in both material-level understanding and device-level measurement of the α-MgAgSb system. First, the phase transitions and common fabrication methods are briefly introduced. Then, the origin of the “phonon glass electron crystal” behavior of α-MgAgSb is thoroughly elucidated with regard to some critical factors, such as the crystal structure, lattice dynamic properties, defect chemistry, microstructure, and band structure. Afterwards, the effective strategies to further enhance the ZT are illustrated, including optimizing the carrier concentration and intrinsic defect engineering. In addition, other feasible methods in theory are also presented. Finally, the conversion efficiency on a single-leg device is presented. In the outlook section, the currently unsolved questions as well as future directions and challenges for this material system are discussed.

中文翻译：

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α-MgAgSb的高热电性能，可用于发电

固态热电设备可以将废热和太阳能转换为电能，从而为能源收集提供了另一条途径，以应对能源可持续性的挑战。基于α-MgAgSb的材料最近作为低温应用（在室温和550 K之间）的一种新的有希望的p型候选材料而受到广泛关注。高品质因数（ZT）在550 K时达到1.2-1.4），并通过实验证明，在225 K的冷端和热端温度差下，转换效率达到了创纪录的8.5％，这具有现实的发电前景。在这篇综述中，我们总结了α-MgAgSb系统在材料水平的理解和设备水平的测量方面的最新进展。首先，简要介绍相变和常见的制造方法。然后，从晶体结构，晶格动力学性质，缺陷化学，微观结构和能带结构等一些关键因素出发，对α-MgAgSb的“声子玻璃电子晶体”行为的起源进行了详尽的阐述。之后，进一步提升ZT的有效策略进行了说明，包括优化载流子浓度和固有缺陷工程。此外，理论上还提出了其他可行的方法。最后，介绍了单脚设备的转换效率。在“展望”部分，讨论了此物料系统当前尚未解决的问题以及未来的方向和挑战。