Theoretical study of long oligothiophene polycations as a model for doped polythiophene

Sanjio S. Zade, Michael Bendikov

Research output: Contribution to journalArticle

44 Citations (Scopus)

Abstract

We investigated the different electronic states of oligothiophene polycations such as tri-, tetra-, hexa-, and octacations (nT3+, nT4+, nT6+, and nT8+) at the B3LYP/6-31G(d) level. 10-, 20-, 30-, and 50-mers of oligothiophene polycations were studied. This is the first time oligothiophene polycations have been studied using density functional theory (DFT). For relatively short (10- or 20-mer) oligothiophene polycations, the ground states are most likely the doublet for trications and the singlet for tetra-, hexa-, and octacations, while longer oligomer polycations (such as the 50-mer) exhibit degeneracy between different spin states. Using bond length alternation, charge distribution, and relative energies data, we showed that the electronic structure of sufficiently long tri- and tetracations (such as the 20- and 30-mer) and hexa- and octacations (such as the 50-mer) appears similar to that of the dications, with the oligothiophene chain separated into well-defined regions of cation radicals (polarons). Charge separation requires a chain length of at least about five thiophene rings per unit charge. Interestingly, one molecule of dopant per five thiophene rings is the typical doping level for polythiophene. Isodesmic reactions were used to assess the stability of oligothiophene polycations in the gas phase.

Original languageEnglish
Pages (from-to)10662-10672
Number of pages11
JournalJournal of Physical Chemistry C
Volume111
Issue number28
DOIs
Publication statusPublished - Jul 19 2007

Fingerprint

Thiophene
thiophenes
Doping (additives)
Polarons
rings
Charge distribution
alternations
Bond length
Electronic states
polarons
Polymers
polarization (charge separation)
Chain length
oligomers
Oligomers
charge distribution
Ground state
Electronic structure
Density functional theory
Thiophenes

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Electronic, Optical and Magnetic Materials
  • Surfaces, Coatings and Films
  • Energy(all)

Cite this

Theoretical study of long oligothiophene polycations as a model for doped polythiophene. / Zade, Sanjio S.; Bendikov, Michael.

In: Journal of Physical Chemistry C, Vol. 111, No. 28, 19.07.2007, p. 10662-10672.

Research output: Contribution to journalArticle

@article{37ce8fdaed6f4c369b63844eb0a5a3bc,
title = "Theoretical study of long oligothiophene polycations as a model for doped polythiophene",
abstract = "We investigated the different electronic states of oligothiophene polycations such as tri-, tetra-, hexa-, and octacations (nT3+, nT4+, nT6+, and nT8+) at the B3LYP/6-31G(d) level. 10-, 20-, 30-, and 50-mers of oligothiophene polycations were studied. This is the first time oligothiophene polycations have been studied using density functional theory (DFT). For relatively short (10- or 20-mer) oligothiophene polycations, the ground states are most likely the doublet for trications and the singlet for tetra-, hexa-, and octacations, while longer oligomer polycations (such as the 50-mer) exhibit degeneracy between different spin states. Using bond length alternation, charge distribution, and relative energies data, we showed that the electronic structure of sufficiently long tri- and tetracations (such as the 20- and 30-mer) and hexa- and octacations (such as the 50-mer) appears similar to that of the dications, with the oligothiophene chain separated into well-defined regions of cation radicals (polarons). Charge separation requires a chain length of at least about five thiophene rings per unit charge. Interestingly, one molecule of dopant per five thiophene rings is the typical doping level for polythiophene. Isodesmic reactions were used to assess the stability of oligothiophene polycations in the gas phase.",
author = "Zade, {Sanjio S.} and Michael Bendikov",
year = "2007",
month = "7",
day = "19",
doi = "10.1021/jp071277p",
language = "English",
volume = "111",
pages = "10662--10672",
journal = "Journal of Physical Chemistry C",
issn = "1932-7447",
publisher = "American Chemical Society",
number = "28",

}

TY - JOUR

T1 - Theoretical study of long oligothiophene polycations as a model for doped polythiophene

AU - Zade, Sanjio S.

AU - Bendikov, Michael

PY - 2007/7/19

Y1 - 2007/7/19

N2 - We investigated the different electronic states of oligothiophene polycations such as tri-, tetra-, hexa-, and octacations (nT3+, nT4+, nT6+, and nT8+) at the B3LYP/6-31G(d) level. 10-, 20-, 30-, and 50-mers of oligothiophene polycations were studied. This is the first time oligothiophene polycations have been studied using density functional theory (DFT). For relatively short (10- or 20-mer) oligothiophene polycations, the ground states are most likely the doublet for trications and the singlet for tetra-, hexa-, and octacations, while longer oligomer polycations (such as the 50-mer) exhibit degeneracy between different spin states. Using bond length alternation, charge distribution, and relative energies data, we showed that the electronic structure of sufficiently long tri- and tetracations (such as the 20- and 30-mer) and hexa- and octacations (such as the 50-mer) appears similar to that of the dications, with the oligothiophene chain separated into well-defined regions of cation radicals (polarons). Charge separation requires a chain length of at least about five thiophene rings per unit charge. Interestingly, one molecule of dopant per five thiophene rings is the typical doping level for polythiophene. Isodesmic reactions were used to assess the stability of oligothiophene polycations in the gas phase.

AB - We investigated the different electronic states of oligothiophene polycations such as tri-, tetra-, hexa-, and octacations (nT3+, nT4+, nT6+, and nT8+) at the B3LYP/6-31G(d) level. 10-, 20-, 30-, and 50-mers of oligothiophene polycations were studied. This is the first time oligothiophene polycations have been studied using density functional theory (DFT). For relatively short (10- or 20-mer) oligothiophene polycations, the ground states are most likely the doublet for trications and the singlet for tetra-, hexa-, and octacations, while longer oligomer polycations (such as the 50-mer) exhibit degeneracy between different spin states. Using bond length alternation, charge distribution, and relative energies data, we showed that the electronic structure of sufficiently long tri- and tetracations (such as the 20- and 30-mer) and hexa- and octacations (such as the 50-mer) appears similar to that of the dications, with the oligothiophene chain separated into well-defined regions of cation radicals (polarons). Charge separation requires a chain length of at least about five thiophene rings per unit charge. Interestingly, one molecule of dopant per five thiophene rings is the typical doping level for polythiophene. Isodesmic reactions were used to assess the stability of oligothiophene polycations in the gas phase.

UR - http://www.scopus.com/inward/record.url?scp=34547504709&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=34547504709&partnerID=8YFLogxK

U2 - 10.1021/jp071277p

DO - 10.1021/jp071277p

M3 - Article

VL - 111

SP - 10662

EP - 10672

JO - Journal of Physical Chemistry C

JF - Journal of Physical Chemistry C

SN - 1932-7447

IS - 28

ER -