基于局域成键分析的热电材料能带工程设计及性能优化

“能带工程”对高性能热电材料的设计和优化具有重要意义，相关研究是当前热电学科领域前沿。然而已有的能带工程案例均通过实验主导，其内在调控机制尚待明晰。基于化合物的局域成键特征分析，本项目提出一种依据掺杂原子特征的能带工程设计方案，以加速高性能热电材料研发。围绕几类具备“浅次能谷”特征的Mg3Sb2、GeSe和BiCuSeO等环境友好型热电材料，本项目拟通过深入解析能带结构和成键机理，构建合适的哈密顿量矩阵描述局域成键特征，探究成键强度变化对能带色散的影响规律，凝练“杂质轨道能级—成键强度—能带色散”的能带工程设计思路，提出优化热电性能的掺杂元素和浓度等指导方案。本项目开展将深化理解能带调控微观机制，丰富热电材料能带工程设计内涵，为设计制备高性能热电材料提供清晰指导。

“Band engineering” plays an important role in the design and optimization of high-performance thermoelectric (TE) materials, and have attracted more and more attention in recent years. However, most of the successful examples were first discovered by experimental studies, while the mechanism behind band tuning were not well understood. Based on the careful analysis of local bonding characters, band engineering is hopeful to be designed according to the atomic features, and the related experimental research will be certainly accelerated. This proposal will focus on several environmentally friendly TE materials with band structure of “shallow sub-valleys”, such as Mg3Sb2, GeSe, BiCuSeO, etc. We will deeply investigate their band dispersion and bonding mechanisms, construct suitable Hamiltonian matrixes to describe the local bonding characters, and reveal the underlying relationship between bond strength variation and electronic band structure. Our goal is to develop an applicable scheme of “orbital energy—bonding strength—band dispersion” for purposive band engineering design, and based on that carry out effective dopants and appropriate doping level for the TE performance enhancement. This research will obtain in-depth understanding about the microcosmic mechanism of band modification, identify the scientific fundamentals of the band engineering concept, and provide direct guidance for the investigations of high performance TE materials.