四元Cu2ZnSnSe4基热电材料输运性能调控机制研究

类金刚石结构Cu2ZnSnSe4基四元体系是一种极具发展前景、亟待发掘的p型热电材料。这类材料的热电优值存在极大的提升空间。然而，对这类体系热电性能调控，尚缺乏深层的微观机制理解。因而，为进一步提升其热电优值，亟需深入研究各类缺陷、电-声子相互作用、拓扑相等对热电输运性质的调控机理，以构建基本物理图像。本项目主要研究Cu2ZnSnSe4基热电材料中的缺陷种类、缺陷配位环境、投影声子态密度、电荷动力学行为、拓扑相结构等。通过原位X射线吸收精细结构谱学，并结合核共振散射、远红外反射率谱等多项同步辐射技术，揭示内禀缺陷、掺杂缺陷、电-声子耦合、电荷输运拓扑相保护等对电子和声子传输的调控机制。旨在解决类金刚石体系中协同优化电热输运性能的关键科学问题。项目成果将为优化设计类似结构高性能热电材料提供新思路，具有重要的科学意义。

Quaternary Cu2ZnSnSe4–based compounds with Diamond-like structure are a family of promising p-type thermoelectric materials to be fully exploited. There is an extremely large room for improving the thermoelectric figure of merit for this family of compounds. Nevertheless, there still lacks profound understanding of the key factors that govern the thermoelectric transport properties of this system. To further improve the thermoelectric figure of merit, it is, therefore, mandatory to establish a fundamental physical picture by deeply understanding the impacts upon the thermoelectric transport behavior as imposed by a variety of defects, electron-phonon interactions, and topological phase, etc. This project mainly investigate the Cu2ZnSnSe4 based thermoelectric materials, revealing the types of defects, defects coordination environment, projected phonon density of states, charge dynamics, and topological phase structures, etc. This project employs multiple synchrotron radiation based techniques such as in situ X-ray Absorption Fine structure spectroscopy, nuclear resonant scattering spectroscopy, and far-infrared reflectance spectroscopy, to explore mechanisms of electron and phonon transport behavior influenced by the intrinsic defects, doping defects, electron-phonon coupling, and topological protection of charge transport. The goal of the project is to address the key scientific issues regarding the synergetic optimization of the thermoelectric transport properties in the diamond-like structured compounds. The findings will be scientifically significant and shed new lights upon the optimizing or designing of high performance thermoelectric materials of similar structures.