Optical properties of ordered vertical arrays of multi-walled carbon nanotubes from FDTD simulations

Abstract

A finite-difference time-domain (FDTD) method is used to model thermal radiative properties of vertical arrays of multi-walled carbon nanotubes (MWCNT). Individual CNTs are treated as solid circular cylinders with an effective dielectric tensor. Consistent with experiments, the results confirm that CNT arrays are highly absorptive. Compared with the commonly used Maxwell-Garnett theory, the FDTD calculations generally predict larger reflectance and absorbance, and smaller transmittance, which are attributed to the diffraction and scattering within the cylinder array structure. The effects of volume fraction, tube length, tube distance, and incident angle on radiative properties are investigated systematically. Low volume fraction and long tubes are more favorable to achieve low reflectance and high absorbance. For a fixed volume fraction and finite tube length, larger periodicity results in larger reflectance and absorbance. The angular dependence studies reveal an optimum incident angle at which the reflectance can be minimized. The results also suggest that an even darker material could be achieved by using CNTs with good alignment on the top surface.

Comments

Optical properties of ordered vertical arrays of multi-walled carbon nanotubes from FDTD simulations. Hua Bao, Xiulin Ruan, and Timothy S. Fisher. Optics Express Vol. 18, Issue 6, pp. 6347-6359 (2010).

Keywords

SILICON NANOWIRE ARRAYS; PHOTOVOLTAIC APPLICATIONS; ABSORPTION ENHANCEMENT; SCATTERING; SPECTRA

DOI

10.1364/OE.18.006347

Citation

Optics Express Vol. 18, Issue 6, pp. 6347-6359 (2010)

Date of this Version

3-2010

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