Colloidal quantum dots (QDs), which consist of inorganic cores surrounded by soft organic ligands, can self-assemble into superlattices exhibiting long-range order. Their tunability, in terms of size, shape, and ligand properties, makes them promising for applications in solar cells, photodetectors, and light-emitting diodes. However, the complex interplay between ligand stiffness, QDs cores-ligands coupling strength, and its impact on QDs' morphology and thermal properties is not well understood. This work employs molecular dynamics simulations to investigate the possibility of modulating the thermal conductivity of QDs superlattices via ligand engineering. It is found that the structural stability of QDs superlattices depends significantly on the interaction strength between the QDs cores and ligands. At lower interaction strengths, the instability manifests itself in a random fusion of the QDs cores, while at intermediate strengths a stable simple cubic lattice structure is maintained. Higher interaction strengths lead to amorphization in the surface regions of QDs core. We observed a nonlinear trend in the thermal conductivity with varying QD-ligand interaction strengths due to competing factors: fusion of QDs cores at lower interaction strengths and increased crosslinking interaction among ligands at higher interaction strengths. The influence of ligand stiffness on thermal conductivity was found to be minimal. This study provides a deep insight into the role of ligand stiffness and interaction strength on structural dynamics and thermal transport in QDs superlattice and demonstrates the feasibility of engineering thermal transport in QDs superlattice via ligand engineering.

中文翻译：

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通过配体工程实现胶体量子点超晶格的非单调热导率调制


胶体量子点（QD）由软有机配体包围的无机核组成，可以自组装成表现出长程有序的超晶格。它们在尺寸、形状和配体特性方面的可调性使其在太阳能电池、光电探测器和发光二极管中的应用前景广阔。然而，配体刚度、量子点核-配体耦合强度之间复杂的相互作用及其对量子点形态和热性能的影响尚不清楚。这项工作采用分子动力学模拟来研究通过配体工程调节量子点超晶格热导率的可能性。研究发现，量子点超晶格的结构稳定性很大程度上取决于量子点核与配体之间的相互作用强度。在较低的相互作用强度下，不稳定性表现为量子点核的随机融合，而在中等强度下，保持稳定的简单立方晶格结构。较高的相互作用强度导致量子点核心表面区域的非晶化。由于竞争因素，我们观察到热导率随 QD-配体相互作用强度的变化而呈现非线性趋势：在较低相互作用强度下 QD 核的融合以及在较高相互作用强度下配体之间的交联相互作用增加。发现配体刚度对热导率的影响很小。这项研究深入了解了配体刚度和相互作用强度对量子点超晶格结构动力学和热传输的作用，并证明了通过配体工程在量子点超晶格中设计热传输的可行性。