Low reflectance of carbon nanotube and nanoscroll-based thin film coatings: a case study

Saini, Sonia; Reshmi, S.; Gouda, Girish M.; Kumar, Sonu; Sriram, K. V.; Bhattacharjee, A. K.

doi:10.1039/d0na01058h

Cited by 11 publications

(17 citation statements)

References 111 publications

(228 reference statements)

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“…The first is deviation of conductance from Drude model and therefore unsuitability of Hagen–Rubens relation for description of the reflectance of these compounds [ 46 ]. The second is macroscopic disorder of graphenic sheets that provides light trapping by multiple reflections as it was discussed for CNT forests [ 47 , 48 ]. The presence of the peculiarity in the UV part of spectra is related to the presence in the composite of some amount of materials with an energy gap.…”

Section: Resultsmentioning

confidence: 99%

Unveiling the Atomic and Electronic Structure of Stacked-Cup Carbon Nanofibers

et al. 2021

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We report results of comprehensive experimental exploration (X-ray photoemission, Raman and optical spectroscopy) of carbon nanofibers (CNFs) in combination with first-principles modeling. Core-level spectra demonstrate prevalence of sp2 hybridization of carbon atoms in CNF with a trace amount of carbon–oxygen bonds. The density functional theory (DFT)-based calculations demonstrated no visible difference between mono- and bilayers because σ-orbitals are related to in-plane covalent bonds. The influence of the distortions on π-peak is found to be significant only for bilayers as a result of π–π interlayer bonds formation. These results are supported by both experimental Raman and XPS valence band spectra. The combination of optical measurements with a theoretical modeling indicates the formation of optically active graphene quantum dots (GQDs) in the CNF matrix, with a radiative relaxation of the excited π* state. The calculated electronic structure of these GQDs is in quantitative agreement with the measured optical transitions and provides an explanation of the absence of visible contribution from these GQDs to the measured valence bands spectra.

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Section: Resultsmentioning

confidence: 99%

Unveiling the Atomic and Electronic Structure of Stacked-Cup Carbon Nanofibers

et al. 2021

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“…In our previous work, high absorptance of the order of 97-98 % was obtained in the visible spectral range from the SWCNT based composite film coatings [6].The motivation to carry out the present work is to develop further understanding about the basic physical processes responsible for the observed high absorptance of the SWCNT based composite films.We try to correlate various structure specific transitions within the absorption band in the energy range 1.8 to 2.3 eV with the observed PL transitions in the similar visible spectral range. Analyses carried out on the absorption and PL data reveal signature of SWCNTs with different chiral indices and diameters in the coated film that are responsible for exhibiting transitions in the energy band E 22 .…”

Section: Introductionmentioning

confidence: 87%

“…Purified SWCNTs were then functionalized using concentrated H 2 SO 4 and HNO 3 with a volume ration of 3:1 and stirring at 70℃ for 8 hrs followed by cooling down of the mixture at room temperature (RT) and neutralizing by rinsing with deionized water. For coated sample, acid treated CNTs mixed with polymer binder and solvent was hand sprayed over Al substrate [6]. Absorption properties of the spray-coated samples were analyzed using a UV-VIS-NIR spectrometer, PerkinElmer Lambda 950 in the wavelength range of 500 to 750 nm.…”

Section: Methodsmentioning

confidence: 99%

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Structure assigned optical transitions from single walled carbon nanotube based high absorber composite thin film coatings

Saini

Reshmi

Gouda

et al. 2022

IOP Conf. Ser.: Mater. Sci. Eng.

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Single walled carbon nanotubes (SWCNTs) exhibit unique electronic and optical properties owing to their one-dimensional (1D) structures that are described by a set of chiral indices (n, m), diameter (d) and chiral angle (θ). Absorption and optical spectroscopies are powerful techniques to determine the structure and diameter distribution of the SWCNTs through bulk measurements. In this work, we correlate structure assigned absorption features with the corresponding optical transitions observed from the SWCNT based high absorber composite thin film coatings. Various optical signatures demonstrated here are direct manifestation of electronic transitions happening within the sharp van Hove (vH) states of valence band, v2 to conduction band, c2 from SWCNTs of particular chiral indices and diameter. These transitions arising within the vH singularities due to unique 1D structures of SWCNTs, correspond to the energy band E22. The presentwork based on empirical calculations according to tight binding model (TB) approximation, represents unique way of correlating structure assigned absorption features with the optical transitions that can have direct impact in tuning the bandgap of SWCNTs of specific diameter and chirality for nanoelectronics and nanophotonic applications.

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“…Nanoscrolls. Graphene nanoscrolls [56,57,77] have received great attention due to their unusual properties and potential applications [78][79][80][81][82]. They consist in carbon-based structures obtained by rolling a graphene layer into a cylindrical geometry [56], and exhibit some exciting electronic and mechanical properties due to their distinctively different structure [83,84], making them conceptually interesting and experimentally relevant.…”

Section: Graphene Nanoscrollsmentioning

confidence: 99%

Graphene, Dirac equation and analogue gravity

Gallerati

2022

Preprint

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We provide an updated study of some electronic properties of graphene nanoscrolls, exploiting a related curved space Dirac equation for the charge carriers. To this end, we consider an explicit parametrization in cylindrical coordinates, together with analytical solutions for the pseudoparticle modes living on the two-dimensional background. These results are then used to obtain a compact expression for the sample optical conductivity, deriving from a Kubo formula adapted to the 1+2 dimensional curved space. The latter formulation is then adopted to perform some simulations for a cylindrical nanoscroll geometry.

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Low reflectance of carbon nanotube and nanoscroll-based thin film coatings: a case study

Abstract: Research on carbon materials-based thin films with low light reflectance has received paramount importance in order to have high absorber coatings for stray light control applications. We report here a...

Cited by 11 publications

References 111 publications

Unveiling the Atomic and Electronic Structure of Stacked-Cup Carbon Nanofibers

Unveiling the Atomic and Electronic Structure of Stacked-Cup Carbon Nanofibers

Structure assigned optical transitions from single walled carbon nanotube based high absorber composite thin film coatings

Graphene, Dirac equation and analogue gravity

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