Atomistic Design of Thermal and Electrical Transport in Materials with Dislocations: From High Power Electronics to Thermoelectrics

位错材料中热电传输的原子设计：从高功率电子到热电

• 批准号: 429844621
• 负责人: Professor Dr. Thomas Frauenheim
• 金额: --
• 依托单位: Profesur für Computational Materials Science
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2023-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/429844621?language=en
• 关键词: Atomistic; Design; Thermal; Electrical; Transport

Recent advances in material synthesis controlled by dislocations suggest the novel possibility of engineering dislocations in nanomaterials. To leverage these advances and guide the synthesis of materials with engineered dislocations, accurate models for the dislocation-transport property relationship are needed. We propose research to advance the atomistic computational techniques and theoretical con-cepts needed to understand and predict the structure-transport properties across the material space. The extended strain fields and dynamic fluttering of the dislocations, and their impact on electronic properties are computationally tractable with the density functional theory based tight-binding (DFTB) method. To enable predictions in the thermal domain, we propose to couple DFTB with (i) a many-body non-equilibrium Green’s-function approach for quantum phononic transport with inter-atomic anharmonicity, (ii) an equilibrium objective molecular dynamics method for computing phonon band structure, lifetime, and group velocity calculations, and (iii) wave packet methods for studying phonon propagation and scattering. We will apply the developed tools to investigate ways to impart maximal or minimal lattice ther-mal conductivity while maintaining a large charge carrier mobility and Seebeck coefficient in bulk, one-dimensional, and two-dimensional materials. (i) Simulations of dislocations in bulk materials will target an understanding of the experimentally observed dramatic improvements in the thermoelectric figure of merit in materials with low intrinsic thermal conductivities and em-bedded dense dislocation arrays along grain boundaries. (ii) Nanowires are attractive nanostructures for achieving high thermoelectric performances, but the impact of dislocations located at their core is unknown. Simulations of nanowires storing dislocations aim to uncover a new important mechanism (phonon-dislocation scattering) for boosting the thermoelectric figure of merit. (iii) Two-dimensional materials are of tremendous importance for nanoelectronics devices, but the arrays of dislocations located at their grain boundaries (inherent extended defects) are prone to induce unwanted effects like severe self-heating. Investigations will un-cover dislocations array models that deliver optimal electrical charge transport with minimum heat generation at the grain boundaries.

由位错控制的材料合成的最新进展表明，在纳米材料中进行工程化的位错具有新的可能性。为了利用这些进展并指导具有工程位错的材料的合成，位错-输运性质关系的准确模型是必要的。我们建议进行研究，以推进理解和预测跨材料空间的结构-传输特性所需的原子计算技术和理论概念。用基于密度泛函理论的紧束缚(DFTB)方法计算了位错的扩展应变场和动态颤振及其对电子性质的影响。为了能够在热域中进行预测，我们建议将DFTB与(I)用于原子间非谐性量子声子输运的多体非平衡格林函数方法，(Ii)用于计算声子能带结构、寿命和群速度的平衡客观分子动力学方法，以及(Iii)用于研究声子传播和散射的波包方法相结合。我们将应用开发的工具来研究如何在保持大的载流子迁移率和塞贝克系数的同时，在体相、一维和二维材料中提供最大或最小的晶格热导。(I)对块状材料中位错的模拟将以理解实验观察到的具有低本征热导率和沿晶界嵌入致密位错阵列的材料的热电优值系数的显著改善为目标。(Ii)纳米线是一种很有吸引力的纳米结构，可以实现高热电性能，但位于其核心的位错的影响尚不清楚。对存储位错的纳米线的模拟旨在揭示一种新的提高热电优值的重要机制(声子-位错散射)。(Iii)二维材料对纳米电子器件非常重要，但位于其晶界的位错阵列(固有的扩展缺陷)容易引起严重的自热等不必要的效应。研究将揭示位错阵列模型，该模型在晶界产生的热量最少的情况下提供最佳的电荷传输。