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Issue 71, 2017, Issue in Progress
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Dimension-dependent band alignment and excitonic effects in graphitic carbon nitride: a many-body perturbation and time-dependent density functional theory study

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Abstract

First-principles many-body theory and time-dependent density functional theory were used to study the dimension effects on the band alignment and optical properties of s-triazine and graphitic C3N4. The inclusion of quasiparticle corrections is very important to describe the quantum confinement and the enhancement of the electron–electron (e–e) interaction. The calculated quasiparticle gaps range from 4.0 eV (monolayer) to 3.21 eV (tetralayer). The position of the valence band maxima is found to be almost constant, whereas the conduction band minima show a strong quantum confinement effect with a variation of ∼0.7 eV respective to the bulk structure. The calculated frequency-dependent imaginary part of the dielectric function using the Bethe–Salpeter equation shows prominent excitonic effects, where there is a strong redistribution of the spectral weight to lower photon energies in the ultraviolet frequencies where the major part of the absorption occurs. On the other hand, a less intense excitonic absorption in the visible region is due to light polarization perpendicular to the surface plane. In contrast, time-dependent density functional theory also shows a redistribution of the spectral weight in the ultraviolet but it fails to describe the excitonic features in the visible region.

Graphical abstract: Dimension-dependent band alignment and excitonic effects in graphitic carbon nitride: a many-body perturbation and time-dependent density functional theory study

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Publication details

The article was received on 27 Jun 2017, accepted on 08 Sep 2017 and first published on 20 Sep 2017


Article type: Paper
DOI: 10.1039/C7RA07134E
RSC Adv., 2017,7, 44997-45002
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    Dimension-dependent band alignment and excitonic effects in graphitic carbon nitride: a many-body perturbation and time-dependent density functional theory study

    W. F. Espinosa-García, J. M. Osorio-Guillén and C. M. Araujo, RSC Adv., 2017, 7, 44997
    DOI: 10.1039/C7RA07134E

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