Electronic and chemical properties of cyanated, halogenated and thiophene-based linear acene derivatives by first-principles calculations

Molecular modeling plays an essential role in searching for new and better organic electronic materials with excellent electronic and chemical properties to design organic electronic devices. In this research, we have studied some electronic, chemical and vibrational properties of linear acenes (fro...

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Main Author:	Musa, Auwalu
Format:	Thesis
Language:	English
Published:	2016
Subjects:	QC Physics
Online Access:	http://eprints.utm.my/id/eprint/78701/1/AuwaluMusaPFS2016.pdf
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spelling	my-utm-ep.787012018-08-29T07:57:03Z Electronic and chemical properties of cyanated, halogenated and thiophene-based linear acene derivatives by first-principles calculations 2016-07 Musa, Auwalu QC Physics Molecular modeling plays an essential role in searching for new and better organic electronic materials with excellent electronic and chemical properties to design organic electronic devices. In this research, we have studied some electronic, chemical and vibrational properties of linear acenes (from benzene to heptacene), and the additional effect of halogens, cyanate, and thiophene to linear acenes. The possible molecular properties of linear acenes and their derivatives as a function of a number of the fused benzene rings and the total number of carbons were studied. The computation is carried out using NWchem 6.3 code and Molden for molecular structure visualization. Hartree-Fock (HF), Density Functional Theory (DFT) and MØller-Plesset (MP2) level of the theories with B3LYP exchange functional using 6-311G, 6-311G (d,p), 6-311G* and aug-cc-pvdz basis sets are used for calculations. The ground state energy and band gap energy decrease with number of linear acene rings while the nuclear repulsion energy and Coulomb potential increase due to the accumulation of electrons in the bonding states. Additionally, p-bonding electrons increase the highest occupied molecular orbitals (HOMO) energy, and p*-antibonding electrons decrease the lowest occupied molecular orbitals (LUMO) energy with the increase of the acene rings. The p-bonding electrons cause the resonance by delocalization of electrons around the linear acenes molecular structures. It was found that the band gap energy, chemical potential, µ and global hardness, η decrease with the increase in the number of acene rings whereas the electronegativity χ, softness S and electrophilicity ω, increase with the number of linear acene rings. The results show good agreement with theoretical and experimental values. In addition, HOMO and LUMO orbitals energy, ionisation energy, electron affinity and global indices reveal that higher linear acene rings and their derivatives exhibit excellent electronic and chemical properties. However, due to high values of HOMO orbitals energy and low values of LUMO energy lead to low ionisation potential and high electron affinity across the acene derivatives which demonstrate that the materials have more potential application in organic light emitting diodes (OLEDs) and organic field effect transistors (OFETs) than in optical application. 2016-07 Thesis http://eprints.utm.my/id/eprint/78701/ http://eprints.utm.my/id/eprint/78701/1/AuwaluMusaPFS2016.pdf application/pdf en public http://dms.library.utm.my:8080/vital/access/manager/Repository/vital:106123 phd doctoral Universiti Teknologi Malaysia, Faculty of Science Faculty of Science
institution	Universiti Teknologi Malaysia
collection	UTM Institutional Repository
language	English
topic	QC Physics
spellingShingle	QC Physics Musa, Auwalu Electronic and chemical properties of cyanated, halogenated and thiophene-based linear acene derivatives by first-principles calculations
description	Molecular modeling plays an essential role in searching for new and better organic electronic materials with excellent electronic and chemical properties to design organic electronic devices. In this research, we have studied some electronic, chemical and vibrational properties of linear acenes (from benzene to heptacene), and the additional effect of halogens, cyanate, and thiophene to linear acenes. The possible molecular properties of linear acenes and their derivatives as a function of a number of the fused benzene rings and the total number of carbons were studied. The computation is carried out using NWchem 6.3 code and Molden for molecular structure visualization. Hartree-Fock (HF), Density Functional Theory (DFT) and MØller-Plesset (MP2) level of the theories with B3LYP exchange functional using 6-311G, 6-311G (d,p), 6-311G* and aug-cc-pvdz basis sets are used for calculations. The ground state energy and band gap energy decrease with number of linear acene rings while the nuclear repulsion energy and Coulomb potential increase due to the accumulation of electrons in the bonding states. Additionally, p-bonding electrons increase the highest occupied molecular orbitals (HOMO) energy, and p*-antibonding electrons decrease the lowest occupied molecular orbitals (LUMO) energy with the increase of the acene rings. The p-bonding electrons cause the resonance by delocalization of electrons around the linear acenes molecular structures. It was found that the band gap energy, chemical potential, µ and global hardness, η decrease with the increase in the number of acene rings whereas the electronegativity χ, softness S and electrophilicity ω, increase with the number of linear acene rings. The results show good agreement with theoretical and experimental values. In addition, HOMO and LUMO orbitals energy, ionisation energy, electron affinity and global indices reveal that higher linear acene rings and their derivatives exhibit excellent electronic and chemical properties. However, due to high values of HOMO orbitals energy and low values of LUMO energy lead to low ionisation potential and high electron affinity across the acene derivatives which demonstrate that the materials have more potential application in organic light emitting diodes (OLEDs) and organic field effect transistors (OFETs) than in optical application.
format	Thesis
qualification_name	Doctor of Philosophy (PhD.)
qualification_level	Doctorate
author	Musa, Auwalu
author_facet	Musa, Auwalu
author_sort	Musa, Auwalu
title	Electronic and chemical properties of cyanated, halogenated and thiophene-based linear acene derivatives by first-principles calculations
title_short	Electronic and chemical properties of cyanated, halogenated and thiophene-based linear acene derivatives by first-principles calculations
title_full	Electronic and chemical properties of cyanated, halogenated and thiophene-based linear acene derivatives by first-principles calculations
title_fullStr	Electronic and chemical properties of cyanated, halogenated and thiophene-based linear acene derivatives by first-principles calculations
title_full_unstemmed	Electronic and chemical properties of cyanated, halogenated and thiophene-based linear acene derivatives by first-principles calculations
title_sort	electronic and chemical properties of cyanated, halogenated and thiophene-based linear acene derivatives by first-principles calculations
granting_institution	Universiti Teknologi Malaysia, Faculty of Science
granting_department	Faculty of Science
publishDate	2016
url	http://eprints.utm.my/id/eprint/78701/1/AuwaluMusaPFS2016.pdf
_version_	1747818050139193344

Electronic and chemical properties of cyanated, halogenated and thiophene-based linear acene derivatives by first-principles calculations

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