Nature of Excitons in Bidimensional WSe2 by Hybrid Density Functional Theory Calculations
2D tungsten diselenide (2D-WSe2) is one of the most successful bidimensional materials for optoelectronic and photonic applications, thanks to its strong photoluminescence properties and to a characteristic large exciton binding energy. Although these optical properties are widely recognized by the...
Main Authors: | , , |
---|---|
Format: | Article |
Language: | English |
Published: |
MDPI AG
2018-06-01
|
Series: | Nanomaterials |
Subjects: | |
Online Access: | http://www.mdpi.com/2079-4991/8/7/481 |
id |
doaj-486a33ddbe8f435992c5e6bc9e7f6caa |
---|---|
record_format |
Article |
spelling |
doaj-486a33ddbe8f435992c5e6bc9e7f6caa2020-11-25T00:00:49ZengMDPI AGNanomaterials2079-49912018-06-018748110.3390/nano8070481nano8070481Nature of Excitons in Bidimensional WSe2 by Hybrid Density Functional Theory CalculationsHongsheng Liu0Paolo Lazzaroni1Cristiana Di Valentin2Dipartimento di Scienza dei Materiali, Università di Milano Bicocca, via R. Cozzi 55, 20125 Milano, ItalyDipartimento di Scienza dei Materiali, Università di Milano Bicocca, via R. Cozzi 55, 20125 Milano, ItalyDipartimento di Scienza dei Materiali, Università di Milano Bicocca, via R. Cozzi 55, 20125 Milano, Italy2D tungsten diselenide (2D-WSe2) is one of the most successful bidimensional materials for optoelectronic and photonic applications, thanks to its strong photoluminescence properties and to a characteristic large exciton binding energy. Although these optical properties are widely recognized by the scientific community, there is no general understanding of the atomistic details of the excitonic species giving rise to them. In this work, we present a density functional theory investigation of excitons in 2D-WSe2, where we compare results obtained by standard generalized gradient approximation (GGA) methods (including spin-orbit coupling) with those by hybrid density functionals. Our study provides information on the size of the self-trapped exciton, the number and type of atoms involved, the structural reorganization, the self-trapping energy, and the photoluminescence energy, whose computed value is in good agreement with experimental measurements in the literature. Moreover, based on the comparative analysis of the self-trapping energy for the exciton with that for isolated charge carriers (unbound electrons and holes), we also suggest a simplified approach for the theoretical estimation of the excitonic binding energy, which can be compared with previous estimates from different approaches or from experimental data.http://www.mdpi.com/2079-4991/8/7/481excitonself-trappingphotoluminescenceexcitonic binding energymodellingHSEtransition metal dichalcogenides |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Hongsheng Liu Paolo Lazzaroni Cristiana Di Valentin |
spellingShingle |
Hongsheng Liu Paolo Lazzaroni Cristiana Di Valentin Nature of Excitons in Bidimensional WSe2 by Hybrid Density Functional Theory Calculations Nanomaterials exciton self-trapping photoluminescence excitonic binding energy modelling HSE transition metal dichalcogenides |
author_facet |
Hongsheng Liu Paolo Lazzaroni Cristiana Di Valentin |
author_sort |
Hongsheng Liu |
title |
Nature of Excitons in Bidimensional WSe2 by Hybrid Density Functional Theory Calculations |
title_short |
Nature of Excitons in Bidimensional WSe2 by Hybrid Density Functional Theory Calculations |
title_full |
Nature of Excitons in Bidimensional WSe2 by Hybrid Density Functional Theory Calculations |
title_fullStr |
Nature of Excitons in Bidimensional WSe2 by Hybrid Density Functional Theory Calculations |
title_full_unstemmed |
Nature of Excitons in Bidimensional WSe2 by Hybrid Density Functional Theory Calculations |
title_sort |
nature of excitons in bidimensional wse2 by hybrid density functional theory calculations |
publisher |
MDPI AG |
series |
Nanomaterials |
issn |
2079-4991 |
publishDate |
2018-06-01 |
description |
2D tungsten diselenide (2D-WSe2) is one of the most successful bidimensional materials for optoelectronic and photonic applications, thanks to its strong photoluminescence properties and to a characteristic large exciton binding energy. Although these optical properties are widely recognized by the scientific community, there is no general understanding of the atomistic details of the excitonic species giving rise to them. In this work, we present a density functional theory investigation of excitons in 2D-WSe2, where we compare results obtained by standard generalized gradient approximation (GGA) methods (including spin-orbit coupling) with those by hybrid density functionals. Our study provides information on the size of the self-trapped exciton, the number and type of atoms involved, the structural reorganization, the self-trapping energy, and the photoluminescence energy, whose computed value is in good agreement with experimental measurements in the literature. Moreover, based on the comparative analysis of the self-trapping energy for the exciton with that for isolated charge carriers (unbound electrons and holes), we also suggest a simplified approach for the theoretical estimation of the excitonic binding energy, which can be compared with previous estimates from different approaches or from experimental data. |
topic |
exciton self-trapping photoluminescence excitonic binding energy modelling HSE transition metal dichalcogenides |
url |
http://www.mdpi.com/2079-4991/8/7/481 |
work_keys_str_mv |
AT hongshengliu natureofexcitonsinbidimensionalwse2byhybriddensityfunctionaltheorycalculations AT paololazzaroni natureofexcitonsinbidimensionalwse2byhybriddensityfunctionaltheorycalculations AT cristianadivalentin natureofexcitonsinbidimensionalwse2byhybriddensityfunctionaltheorycalculations |
_version_ |
1725443189673820160 |