Triplet excimer formation in platinum-based phosphors: A theoretical study of the roles of Pt-Pt bimetallic interactions and interligand π-π interactions

Dongwook Kim, Jean-Luc Bredas*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

95 Scopus citations

Abstract

We have used density functional theory (DFT) and time-dependent DFT to investigate the geometric and electronic structure and the optical properties of the phosphorescent platinum compounds: Pt(II) (2-(4′,6′- difluorophenyl)pyridinato-N,C2′)(2,4-pentanedionato-O,O) (FPt1) and Pt(II) (2-(4′,6′-difluorophenyl) pyridinato-N,C 2′)(1,3-propanedionato-O,O) (FPt0). We first examined isolated compounds (monomers) and evaluated their photophysical properties at the ground-state and lowest triplet excited-state (T1) geometries; the characteristics of the S0 → T1 transitions are nearly identical in both compounds. Dimers of FPt0 and of FPt1 were then studied in order to shed light, at least qualitatively, on the respective role of Pt-Pt bimetallic interactions and interligand π-π interactions in the formation of excimer structures. While the Pt-Pt interactions are critical for excimer formation, the interligand π-π interactions also play a significant role in determining the optimal excimer geometry and the magnitude of the phosphorescence energy lowering in going from the monomer to the aggregated dimer. The distorted cofacial-type excimer structures found for FPt1, with a Pt-Pt distance around 2.9 Å and interligand distances around 3.5-3.8 Å, lead to phosphorescence energy lowerings with respect to the monomer on the order of 0.7-0.96 eV, in very good agreement with experiment.

Original languageEnglish (US)
Pages (from-to)11371-11380
Number of pages10
JournalJournal of the American Chemical Society
Volume131
Issue number32
DOIs
StatePublished - Aug 19 2009

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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