本征单壁碳纳米管电子结构对电子热导率的研究

Study on Electronic Structure and Electronic Thermal Conductivity of Single-Walled Carbon Nanotubes

摘要: 碳纳米管(CNT)热输运以声子主导、电子辅助为基本特征，电子热导率虽占室温总热导率比例较低，但在高温、高偏压或强电场条件下贡献显著，是调控碳纳米管热性能的重要途径。本文采用密度泛函理论，系统研究扶手椅型与锯齿型单壁碳纳米管(SWNT)的能带结构、带隙特征与费米能级态密度，阐明电子结构参数与电子热导率之间的内在关联。结果表明：扶手椅型SWNT具有更窄的带隙和更高的费米能级态密度，其电子热导率显著优于锯齿型SWNT；管径2 nm为电子结构调控临界值，小于2 nm时量子限域效应主导电子热导率变化。研究揭示了碳纳米管电子热导率的微观调控机制，为碳基导热材料的热性能优化提供理论依据。

Abstract: The thermal transport of carbon nanotubes (CNTs) is characterized by phonon-dominated and electron-assisted contributions. Although electronic thermal conductivity accounts for a small proportion of the total thermal conductivity at room temperature, it becomes significant under high temperature, high bias or strong electric field, serving as a key way to regulate the thermal performance of CNTs. In this paper, density functional theory is adopted to systematically investigate the band structure, band gap characteristics and density of states at the Fermi level of armchair and zigzag single-walled carbon nanotubes (SWNTs), and clarify the inherent correlation between electronic structure parameters and electronic thermal conductivity. The results show that armchair SWNTs possess a narrower band gap and higher density of states at the Fermi level, leading to superior electronic thermal conductivity compared with zigzag SWNTs. A critical diameter of 2 nm exists for electronic structure regulation, and quantum confinement effect dominates the variation of electronic thermal conductivity when the diameter is less than 2 nm. This study reveals the microscopic regulation mechanism of electronic thermal conductivity in CNTs, providing a theoretical basis for the thermal performance optimization of carbon-based thermal conductive materials.