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9 pages, 2997 KiB

Open AccessArticle

Bilayer C₆₀ Polymer/h-BN Heterostructures: A DFT Study of Electronic and Optic Properties

by Leonid A. Chernozatonskii and Aleksey I. Kochaev

Polymers 2024, 16(11), 1580; https://doi.org/10.3390/polym16111580 - 3 Jun 2024

Cited by 2 | Viewed by 1518

Interest in fullerene-based polymer structures has renewed due to the development of synthesis technologies using thin C₆₀ polymers. Fullerene networks are good semiconductors. In this paper, heterostructure complexes composed of C₆₀ polymer networks on atomically thin dielectric substrates are modeled. Small tensile and compressive deformations make it possible to ensure appropriate placement of monolayer boron nitride with fullerene networks. The choice of a piezoelectric boron nitride substrate was dictated by interest in their applicability in mechanoelectric, photoelectronic, and electro-optical devices with the ability to control their properties. The results we obtained show that C₆₀ polymer/h-BN heterostructures are stable compounds. The van der Waals interaction that arises between them affects their electronic and optical properties. Full article

(This article belongs to the Special Issue Polymer Nanocomposites and Their Applications in Device and Construction II)

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9 pages, 3519 KiB

Open AccessArticle

BN Diamane-like Quasicrystal Based on 30° Twisted H-BN Bilayers and Its Approximants: Features of the Atomic Structure and Electronic Properties

by Leonid A. Chernozatonskii and Aleksey I. Kochaev

Crystals 2023, 13(3), 421; https://doi.org/10.3390/cryst13030421 - 28 Feb 2023

Cited by 3 | Viewed by 2142

Abstract

The dodecagonal graphene quasicrystal (GQC) based on a 30° twisted bigraphene has been well investigated. Recently, the sp³-hybridizated carbon analog, the diamane quasicrystal as a H(F) functionalized GQC was proposed. Here we present a study of a similar sp³-hybridizated boron nitride 3-fold symmetry piezoelectric quasicrystal (BNnQC) based on a 30° twisted hexagonal BN bilayer (BNQC). The analysis of the atomic and electronic structures of its approximants based on 29.4° and 27.8° twisted h-BN bilayers has been carried by using of the density functional theory (DFT). The calculated values of the energy gaps ∼5 eV classify this predicted boron nitride material as a new wide-gap 2D quasicrystal. Full article

(This article belongs to the Special Issue Aperiodic Crystals: Theory, Structure and Properties)

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11 pages, 2346 KiB

Open AccessArticle

Diamane-like Films Based on Twisted G/BN Bilayers: DFT Modelling of Atomic Structures and Electronic Properties

by Victor A. Demin and Leonid A. Chernozatonskii

Nanomaterials 2023, 13(5), 841; https://doi.org/10.3390/nano13050841 - 24 Feb 2023

Cited by 6 | Viewed by 2052

Abstract

Diamanes are unique 2D carbon materials that can be obtained by the adsorption of light atoms or molecular groups onto the surfaces of bilayer graphene. Modification of the parent bilayers, such as through twisting of the layers and the substitution of one of the layers with BN, leads to drastic changes in the structure and properties of diamane-like materials. Here, we present the results of the DFT modelling of new stable diamane-like films based on twisted Moiré G/BN bilayers. The set of angles at which this structure becomes commensurate was found. We used two commensurate structures with twisted angles of θ = 10.9° and θ = 25.3° with the smallest period as the base for the formation of the diamane-like material. Previous theoretical investigations did not take into account the incommensurability of graphene and boron nitride monolayers when considering diamane-like films. The double-sided hydrogenation or fluorination of Moiré G/BN bilayers and the following interlayer covalent bonding led to the opening of a gap up to 3.1 eV, which was lower than the corresponding values of h-BN and c-BN. The considered G/BN diamane-like films offer great potential in the future for a variety of engineering applications. Full article

(This article belongs to the Section 2D and Carbon Nanomaterials)

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11 pages, 3004 KiB

Open AccessArticle

Ultra-Low Thermal Conductivity of Moiré Diamanes

by Suman Chowdhury, Victor A. Demin, Leonid A. Chernozatonskii and Alexander G. Kvashnin

Membranes 2022, 12(10), 925; https://doi.org/10.3390/membranes12100925 - 25 Sep 2022

Cited by 7 | Viewed by 2676

Abstract

Ultra-thin diamond membranes, diamanes, are one of the most intriguing quasi-2D films, combining unique mechanical, electronic and optical properties. At present, diamanes have been obtained from bi- or few-layer graphene in AA- and AB-stacking by full hydrogenation or fluorination. Here, we study the [...] Read more.

θ

between layers forming a Moiré pattern. The combination of DFT calculations and machine learning interatomic potentials makes it possible to perform calculations of the lattice thermal conductivity of such diamanes with twist angles

θ

of 13.2

^{\circ}

, 21.8

^{\circ}

and 27.8

^{\circ}

using the solution of the phonon Boltzmann transport equation. Obtained results show that Moiré diamanes exhibit a wide variety of thermal properties depending on the twist angle, namely a sharp decrease in thermal conductivity from high for “untwisted” diamanes to ultra-low values when the twist angle tends to 30

^{\circ}

, especially for hydrogenated Moiré diamanes. This effect is associated with high anharmonicity and scattering of phonons related to a strong symmetry breaking of the atomic structure of Moiré diamanes compared with untwisted ones. Full article

(This article belongs to the Special Issue Modeling and Simulation of Polymeric Membrane)

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21 pages, 8364 KiB

Open AccessReview

Fully Hydrogenated and Fluorinated Bigraphenes–Diamanes: Theoretical and Experimental Studies

by Leonid A. Chernozatonskii, Victor A. Demin and Dmitry G. Kvashnin

C 2021, 7(1), 17; https://doi.org/10.3390/c7010017 - 2 Feb 2021

Cited by 26 | Viewed by 4337

Abstract

Diamanes are 2D diamond-like films that are nanometers in thickness. Diamanes can exist as bilayer or multilayer graphene with various modes of stacking and interlayer covalent sp³ bonds. The term “diamane” is used broadly for a variety of diamond-like materials at the nanoscale, from individual diamond clusters to nanocrystal films. A short overview of recent progress in the investigation of diamanes, starting from the first theoretical predictions to practical realization, is presented. The results of both theoretical and experimental studies on diamanes with various atomic structures and types of functionalization are considered. It is shown that diamanes are stronger than graphene and graphane and have wide bandgaps ranging from 3.1 to 4.5 eV depending on the structure. Diamane-like structures have been obtained using different experimental techniques, and their structures have been determined by Raman spectroscopy. The potential applications of these carbon nanostructures are briefly reviewed. Full article

(This article belongs to the Special Issue 2D Ultrathin Carbon Films)

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