Nat Mater. 2012 Mar 11;11(5):422-5. doi: 10.1038/nmat3273.
Advanced thermoelectric technology offers a potential for converting waste industrial heat into useful electricity, and an emission-free method for solid state cooling. Worldwide efforts to find materials with thermoelectric figure of merit, zT values significantly above unity, are frequently focused on crystalline semiconductors with low thermal conductivity. Here we report on Cu(2-x)Se, which reaches a zT of 1.5 at 1,000 K, among the highest values for any bulk materials. Whereas the Se atoms in Cu(2-x)Se form a rigid face-centred cubic lattice, providing a crystalline pathway for semiconducting electrons (or more precisely holes), the copper ions are highly disordered around the Se sublattice and are superionic with liquid-like mobility. This extraordinary 'liquid-like' behaviour of copper ions around a crystalline sublattice of Se in Cu(2-x)Se results in an intrinsically very low lattice thermal conductivity which enables high zT in this otherwise simple semiconductor. This unusual combination of properties leads to an ideal thermoelectric material. The results indicate a new strategy and direction for high-efficiency thermoelectric materials by exploring systems where there exists a crystalline sublattice for electronic conduction surrounded by liquid-like ions.
先进的热电技术提供了将工业废热转化为有用电能的潜力，以及一种无排放的固态冷却方法。全世界都在努力寻找具有显著高于单位的热电优值（zT 值）的材料，通常集中在具有低热导率的晶态半导体上。在这里，我们报告了 Cu(2-x)Se，它在 1000 K 时的 zT 值达到 1.5，是任何块状材料中最高的之一。虽然 Cu(2-x)Se 中的 Se 原子形成了刚性的面心立方晶格，为半导体电子（或更确切地说是空穴）提供了晶体通道，但铜离子在 Se 亚晶格周围高度无序，具有液态的迁移率，是超离子的。在 Cu(2-x)Se 中，Se 亚晶格周围的铜离子这种非凡的“液态”行为导致晶格热导率本质上非常低，从而使这种简单的半导体具有高 zT 值。这种不寻常的组合特性导致了一种理想的热电材料。这些结果表明，通过探索电子传导存在晶体亚晶格而周围是液态离子的系统，为高效热电材料提供了一种新的策略和方向。
