Excitation energy transfer within covalent tetrahedral perylenediimide tetramers and their intermolecular aggregates

Charusheela Ramanan, Chul Hoon Kim, Tobin J Marks, Michael R Wasielewski

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

Perylenediimides (PDIs) offer a number of attractive characteristics as alternatives to fullerenes in organic photovoltaics (OPVs), including favorable orbital energetics, high extinction coefficients in the visible spectral region, photostability, and the capacity to self-assemble into ordered nanostructures. However, energy transfer followed by charge separation in PDI assemblies must kinetically out-compete excimer formation that limits OPV performance. We report on the excitation energy transfer (EET) rate in a covalently linked PDI tetramer in which the PDI chromophores are arranged in a tetrahedral geometry about a tetraphenyladamantane core. Transient absorption spectroscopy of the tetramer in CH2Cl2 reveals a laser intensity-dependent fast absorption decay component indicative of singlet-singlet annihilation resulting from intramolecular EET. Femtosecond fluorescence anisotropy measurements show that the EET time constant τ = 6 ps, which is similar to that predicted for a through-space Förster EET mechanism. Concentration-dependent steady-state spectroscopic studies reveal the formation of intermolecular aggregates of the tetramers in toluene. The aggregates are formed by cofacial π-stacking interactions between PDIs of neighboring tetramers. Transient absorption spectra of the aggregated tetramers in toluene solution demonstrate long-lived excited-state decay dynamics (τ ∼ 30 ns) in agreement with previous observations of PDI excimers.

Original languageEnglish
Pages (from-to)16941-16950
Number of pages10
JournalJournal of Physical Chemistry C
Volume118
Issue number30
DOIs
Publication statusPublished - Jul 31 2014

Fingerprint

Excitation energy
Energy transfer
energy transfer
excitation
excimers
Toluene
toluene
Fullerenes
decay
polarization (charge separation)
Chromophores
Absorption spectroscopy
Excited states
assemblies
chromophores
time constant
fullerenes
Absorption spectra
Nanostructures
absorption spectroscopy

ASJC Scopus subject areas

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

Cite this

Excitation energy transfer within covalent tetrahedral perylenediimide tetramers and their intermolecular aggregates. / Ramanan, Charusheela; Kim, Chul Hoon; Marks, Tobin J; Wasielewski, Michael R.

In: Journal of Physical Chemistry C, Vol. 118, No. 30, 31.07.2014, p. 16941-16950.

Research output: Contribution to journalArticle

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