Gao Dezheng, Wen Yi, Bai Shulin, Wang Siqi, Liu Shibo, Li Yichen, Wang Lei, Zang Wujing, Su Xianli, Gao Xiang, Xie Hongyao, Zhao Li-Dong
School of Materials Science and Engineering, Beihang University, Beijing, 100191, China.
State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan, 430070, China.
Small. 2024 Dec;20(50):e2407556. doi: 10.1002/smll.202407556. Epub 2024 Sep 30.
Ideal thermoelectrics shall possess a high average ZT, which relies on high carrier mobility and appropriate carrier density at operating temperature. However, conventional doping usually results in a temperature-independent carrier concentration, making performance optimization over a wide temperature range be challenging. This work demonstrates the combination of lattice plainification and dynamic doping strategies is an effective route to boost the average ZT of N-type PbSe. Because Sn and Pb have similar ionic radii and electronegativity, this allows Sn to fill the intrinsic Pb vacancies and effectively improves the carrier mobility of PbSe to 1300 cm V s. Furthermore, a trace amount of Cu is introduced into the Sn-filled PbSe to optimize the carrier concentration. The extra Cu is situated in the interstitial sides of the lattice, which undergoes a dissolution-precipitation process with temperature, leading to a strongly temperature-dependent carrier density in the material. This dynamic doping effectively improves the electrical transport properties and is also valid to suppress the lattice thermal conductivity. Ultimately, the resulting PbSnSe+3‰Cu obtains a maximum ZT of ≈1.7 at 800 K and an average ZT of ≈1.0, with a 7.7% power generation efficiency in a single-arm device, showing significant potential for commercial application.
理想的热电材料应具有较高的平均热电优值（ZT），这取决于较高的载流子迁移率和工作温度下合适的载流子密度。然而，传统的掺杂通常会导致载流子浓度与温度无关，使得在宽温度范围内优化性能具有挑战性。这项工作表明，晶格平面化和动态掺杂策略相结合是提高N型PbSe平均ZT的有效途径。由于Sn和Pb具有相似的离子半径和电负性，这使得Sn能够填充本征Pb空位，并有效地将PbSe的载流子迁移率提高到1300 cm V s。此外，将微量的Cu引入到Sn填充的PbSe中以优化载流子浓度。额外的Cu位于晶格的间隙位置，其随温度经历溶解-沉淀过程，导致材料中载流子密度强烈依赖于温度。这种动态掺杂有效地改善了电输运性能，并且对于抑制晶格热导率也有效。最终，所得的PbSnSe+3‰Cu在800 K时获得了约1.7的最大ZT和约1.0的平均ZT，在单臂器件中具有7.7%的发电效率，显示出显著的商业应用潜力。
