Enhancement of reflectance of densified vertically aligned carbon nanotube forests
Vertically aligned carbon nanotubes (VACNTs), also known as a carbon nanotube (CNT) forest, are a porous material that is well known for its exceptional optical absorbance property. The reflectance from a VACNT forest has been reported to be as low as 0.045% [1,2]. It is known as the darkest mate...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English English |
| Published: |
Korean Carbon Society
2016
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| Subjects: | |
| Online Access: | http://irep.iium.edu.my/50573/ http://irep.iium.edu.my/50573/ http://irep.iium.edu.my/50573/ http://irep.iium.edu.my/50573/1/%5B67-70%5D-11.pdf http://irep.iium.edu.my/50573/4/50573-Enhancement%20of%20reflectance%20of%20densified%20vertically%20aligned%20carbon%20nanotube%20forests_SCOPUS.pdf |
| Summary: | Vertically aligned carbon nanotubes (VACNTs), also known as a carbon nanotube (CNT)
forest, are a porous material that is well known for its exceptional optical absorbance property.
The reflectance from a VACNT forest has been reported to be as low as 0.045% [1,2].
It is known as the darkest material on Earth. Because of its remarkable material properties,
it has various other applications as gas sensors [3], pressure sensors [4], temperature sensors
[5], and strain sensors [6]. Recently, various efforts have been made to mechanically manipulate
the vertical structure of the nanotubes in the CNT forest and to conduct their optical
characterization [7,8]. Optical reflection from bare VACNTs has also been investigated at
different wavelengths by Wąsik et al. [9]. Controlled densification by wetting of the CNT
forest is another post processing technique that has been reported by other researchers [10].
A densification process is necessary to make the CNT forest useful as a future electronics
interconnect [10]. However, no study has been done so far on the optical behavior of CNT
forests densified by a wetting process. In this letter, for the first time, we investigate and
explain the nature of the optical reflectance of densified VACNTs.
Fig. 1 illustrates how the CNT forest is able to absorb most incident light. It was reported
elsewhere that VACNT arrays are highly porous [11]. As a result, when incident light enters
the bare CNT forest, it goes through several internal reflection-absorption cycles via individual
nanotubes and finally makes its way out of the CNT forest as shown in Fig. 1b. Hence,
a very low amount of light bounces back (approximately 0.045%) [1,2].
Mathematically, a simple model can be developed to estimate the final amount of light
coming out of a CNT forest after several internal reflections; this process is explained
by eq (1): |
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