Two-photon absorption in quadrupolar π-conjugated molecules: Influence of the nature of the conjugated bridge and the donor-acceptor separation

Egbert Zojer*, David Beljonne, Peter Pacher, Jean-Luc Bredas

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

72 Scopus citations

Abstract

Quadrupolar-type substitution of π-conjugated chromophores with donor and acceptor groups has been shown to increase their two-photon absorption (TPA) response by up to two orders of magnitude. Here, we apply highly correlated quantum-chemical calculations to evaluate the impact of the nature of conjugated bridge and the charge-transfer distance on that enhancement. We compare chromophores with phenylenevinylene-, thienylenevinylene-, polyene-, and indenofluorene-type backbones substituted by dimethylamino and cyano groups. In all compounds, we find a strongly TPA-active Ag state (either 2Ag or 3Ag) in the low-energy region, as well as a higher lying TPA-active state (mAg) at close to twice the energy of the lowest lying one-photon allowed state; the smaller energy detuning in the mAg states results in very large TPA cross sections δ. We also investigate the influence of the degree of ground-state polarization on TPA. Independent of the nature of the backbone and the donor-acceptor separation, δ displays the same qualitative evolution with a maximum before the cyanine-like limit; the highest TPA cross sections are calculated for distirylbenzene- and polyene-based systems.

Original languageEnglish (US)
Pages (from-to)2668-2680
Number of pages13
JournalChemistry - A European Journal
Volume10
Issue number11
DOIs
StatePublished - Jun 7 2004

Keywords

  • Computer chemistry
  • Electron correlation
  • Nonlinear optics
  • Structure-property relationships
  • Two-photon absorption

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Organic Chemistry

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