Theoretical study on the effects of nitrogen and methyl substitution on tris-(8-hydroxyquinoline) aluminum: An efficient exciton blocking layer for organic photovoltaic cells

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Abstract

We studied the effect of nitrogen and methyl substitution on tris-(8-hydroxyquinoline) aluminum (Alq 3) with density functional theory, which has been adopted as an exciton blocking layer (EBL) in organic photovoltaic cells (OPVCs). The substitution of electron withdrawing nitrogen on the phenoxide moiety of Alq 3 lowers the highest molecular orbital (HOMO) level, thus photogenerated excitons can be effectively blocked in OPVC. Additional substitution of methyl on the pyridine moiety makes that Alq 3 has a smaller electron reorganization energy, which results in higher electron mobility with keeping HOMO level almost intact. Therefore, nitrogen and methyl simultaneous substitution shows high performance both in exciton blocking and electron mobility. This is the origins of the short circuit current enhancement in OPVC with 4-hydroxy-8-methyl-1,5-naphthyridine aluminum chelate (Alq 3 with the substitution of both nitrogen and methyl group) EBL.

Original languageEnglish
Article number034704
JournalJournal of Chemical Physics
Volume137
Issue number3
DOIs
Publication statusPublished - 2012 Jul 21

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Photovoltaic cells
photovoltaic cells
Substitution reactions
Nitrogen
excitons
substitutes
aluminum
nitrogen
Electron mobility
electron mobility
Naphthyridines
Electrons
Molecular orbitals
short circuit currents
Aluminum
chelates
Short circuit currents
Density functional theory
pyridines
molecular orbitals

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

Cite this

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title = "Theoretical study on the effects of nitrogen and methyl substitution on tris-(8-hydroxyquinoline) aluminum: An efficient exciton blocking layer for organic photovoltaic cells",
abstract = "We studied the effect of nitrogen and methyl substitution on tris-(8-hydroxyquinoline) aluminum (Alq 3) with density functional theory, which has been adopted as an exciton blocking layer (EBL) in organic photovoltaic cells (OPVCs). The substitution of electron withdrawing nitrogen on the phenoxide moiety of Alq 3 lowers the highest molecular orbital (HOMO) level, thus photogenerated excitons can be effectively blocked in OPVC. Additional substitution of methyl on the pyridine moiety makes that Alq 3 has a smaller electron reorganization energy, which results in higher electron mobility with keeping HOMO level almost intact. Therefore, nitrogen and methyl simultaneous substitution shows high performance both in exciton blocking and electron mobility. This is the origins of the short circuit current enhancement in OPVC with 4-hydroxy-8-methyl-1,5-naphthyridine aluminum chelate (Alq 3 with the substitution of both nitrogen and methyl group) EBL.",
author = "Hyunbok Lee and Kwangho Jeong and Cho, {Sang Wan} and Yeonjin Yi",
year = "2012",
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language = "English",
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journal = "Journal of Chemical Physics",
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TY - JOUR

T1 - Theoretical study on the effects of nitrogen and methyl substitution on tris-(8-hydroxyquinoline) aluminum

T2 - An efficient exciton blocking layer for organic photovoltaic cells

AU - Lee, Hyunbok

AU - Jeong, Kwangho

AU - Cho, Sang Wan

AU - Yi, Yeonjin

PY - 2012/7/21

Y1 - 2012/7/21

N2 - We studied the effect of nitrogen and methyl substitution on tris-(8-hydroxyquinoline) aluminum (Alq 3) with density functional theory, which has been adopted as an exciton blocking layer (EBL) in organic photovoltaic cells (OPVCs). The substitution of electron withdrawing nitrogen on the phenoxide moiety of Alq 3 lowers the highest molecular orbital (HOMO) level, thus photogenerated excitons can be effectively blocked in OPVC. Additional substitution of methyl on the pyridine moiety makes that Alq 3 has a smaller electron reorganization energy, which results in higher electron mobility with keeping HOMO level almost intact. Therefore, nitrogen and methyl simultaneous substitution shows high performance both in exciton blocking and electron mobility. This is the origins of the short circuit current enhancement in OPVC with 4-hydroxy-8-methyl-1,5-naphthyridine aluminum chelate (Alq 3 with the substitution of both nitrogen and methyl group) EBL.

AB - We studied the effect of nitrogen and methyl substitution on tris-(8-hydroxyquinoline) aluminum (Alq 3) with density functional theory, which has been adopted as an exciton blocking layer (EBL) in organic photovoltaic cells (OPVCs). The substitution of electron withdrawing nitrogen on the phenoxide moiety of Alq 3 lowers the highest molecular orbital (HOMO) level, thus photogenerated excitons can be effectively blocked in OPVC. Additional substitution of methyl on the pyridine moiety makes that Alq 3 has a smaller electron reorganization energy, which results in higher electron mobility with keeping HOMO level almost intact. Therefore, nitrogen and methyl simultaneous substitution shows high performance both in exciton blocking and electron mobility. This is the origins of the short circuit current enhancement in OPVC with 4-hydroxy-8-methyl-1,5-naphthyridine aluminum chelate (Alq 3 with the substitution of both nitrogen and methyl group) EBL.

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