余愿: Designing thermoelectrics through metavalent bonds

Metavalent bonding (MVB) describes a unique, half-filled σ-bond characterized by a single electron between adjacent atoms. This bond is defined by a competition between electron localization and delocalization, granting metavalent solids properties like moderate electrical conductivity, high optical dielectric constant, large Born effective charge, and strong lattice anharmonicity. These features are ideal for thermoelectrics, which require high electrical conductivity, a high Seebeck coefficient, and low thermal conductivity. A chemical bonding map, based on quantum mechanics, can classify bonding types and guides the discovery of new thermoelectric materials. Moreover, the thermoelectric performance of metavalent solids can be tailored by doping, which adjusts electronic states or microstructures, providing additional ways to control electron and phonon transport. Lastly, tailoring MVB at defects like grain boundaries presents new opportunities for thermoelectric design. Overall, MVB offers significant potential for breakthroughs in thermoelectric materials. 余愿博士目前在亚琛工业大学（德国精英大学）担任课题组组长、研究员、PI。他于2012年和2017年获得合肥工业大学学士与博士学位。于2018-2022年在德国亚琛工业大学从事博士后研究工作，合作导师为德国科学院院士Matthias Wuttig教授。于2022年起在亚琛工大担任Group Leader，从事热电材料、相变材料、超价键（metavalent bonding）理论、以及三维原子探针（APT）技术等相关工作。迄今共计发表SCI论文95篇，总计被引用4000次，H因子33。以通讯和第一/共一作者在Science, Nat. Mater., Nat. Commun.(4), Adv. Mater., Mater. Today, Energy Environ. Sci.(2), J. Am. Chem. Soc.(2), Adv. Energy Mater.(5), Adv. Funct. Mater.(10)等期刊发表论文47篇，其中IF>15的文章33篇。担任包括Science在内的几十种知名期刊审稿人，担任中国科技期刊卓越行动计划高起点新刊Nano Research Energy以及金属学报英文版的青年编委。