Boosting electronic transport in carbon nanotubes by isotopic disorder

同位素无序碳纳米管中的热输运

Thermal transport in isotopically disordered carbon nanotubes

本文研究了同位素无序碳纳米管的声子热导率。特别是，作为系统长度的函数的热导率的行为进行了研究，使用格林函数技术来计算整个系统的传输。该方法是使用线性缩放算法，这使我们能够达到系统的长度高达$L=2.5μ$ m（高达40万个原子）。对于1D系统，观察到电导率随系统尺寸$L$而发散。我们还观察到一个显着减少的实验尺寸的系统的热导率（约80%，在室温下为$L = 2.5$ $μ$ m），当引入了大部分的同位素无序。与格林函数技术得到的结果进行比较，得到的结果与玻尔兹曼描述的热传输。有一个很好的协议，这两种方法之间的系统的实验规模，即使在存在安德森局域化。这是特别有趣的，因为使用玻尔兹曼方程的传输的计算是少得多的计算昂贵的，使得更大的系统可以用这种方法进行研究。

同位素修饰单壁碳纳米管对活细胞的多重多色拉曼成像

Multiplexed Multi-Color Raman Imaging of Live Cells with Isotopically Modified Single Walled Carbon Nanotubes

我们发现，具有不同同位素组成的单壁碳纳米管表现出不同的拉曼G带峰，可用于生物系统的多路复用多色拉曼成像。具有特异性受体的癌细胞选择性地用3种不同颜色的SWNT标记，SWNT与各种靶向配体缀合，包括Herceptin、抗Her2、Erbitux、抗Her1和RGD肽，允许以多重方式对细胞进行多色拉曼成像。SWNT拉曼信号对光漂白具有高度鲁棒性，允许长期成像和跟踪。SWNT拉曼信号具有窄峰特征，很容易与自发荧光背景区分开来。单壁碳纳米管的拉曼激发和散射光子位于近红外区，是生物体内外最透明的光学窗口。因此，单壁碳纳米管是一种新型的拉曼标记物，有望用于多重生物检测和成像。

Encapsulated Nanowires: Boosting Electronic Transport in Carbon Nanotubes

The electrical conductivity of metallic carbon nanotubes (CNTs) quickly saturates with respect to bias voltage due to scattering from a large population of optical phonons. Decay of these dominant scatterers in pristine CNTs is too slow to offset an increased generation rate at high voltage bias. We demonstrate from first principles that encapsulation of 1D atomic chains within a single-walled CNT can enhance decay of "hot" phonons by providing additional channels for thermalisation. Pacification of the phonon population growth reduces electrical resistivity of metallic CNTs by 51% for an exam…

Reducing the thermal conductivity of carbon nanotubes below the random isotope limit

We find that introducing segmented isotopic disorder patterns may considerably reduce the thermal conductivity of pristine carbon nanotubes below the uncorrelated disorder value. This is a result of the interplay between different length scales in the phonon scattering process. We use ab-initio atomistic Green's function calculations to quantify the effect of various types of segmentation similar to that experimentally produced by coalescence of isotope-engineered fullerenes.

Computational study of the thermal conductivity in defective carbon nanostructures

We use non-equilibrium molecular dynamics simulations to study the adverse role of defects including isotopic impurities on the thermal conductivity of carbon nanotubes, graphene and graphene nanoribbons. We find that even in structurally perfect nanotubes and graphene, isotopic impurities reduce thermal conductivity by up to one half by decreasing the phonon mean free path. An even larger thermal conductivity reduction, with the same physical origin, occurs in presence of structural defects including vacancies and edges in narrow graphene nanoribbons. Our calculations reconcile results of for…

Boosting Thermoelectric Power Factor of Carbon Nanotube Networks with Excluded Volume by Co-embedded Microparticles

Carbon nanotube (CNTs) networks embedded in polymer matrix have been extensively studied over the recent years as a flexible thermoelectric (TE) transport medium. However, their power factor has been largely limited by the relatively inefficient tunneling transport at junctions between CNTs and the low density of conducting channels through the networks. In this work, we demonstrate that significant enhancement of power factor is possible by adding electrically insulating microscale particles in CNT networks. When silica particles of a few micrometer diameters were co-embedded in single-walled…