Low-energy charge-transfer excitons in organic solids from first-principles: The case of pentacene

Sahar Sharifzadeh*, Pierre Darancet, Leeor Kronik, Jeffrey B. Neaton

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

181 Scopus citations

Abstract

The nature of low energy optical excitations, or excitons, in organic solids is of central relevance to many optoelectronic applications, including solar energy conversion. Excitons in solid pentacene, a prototypical organic semiconductor, have been the subject of many experimental and theoretical studies, with differing conclusions as to the degree of their charge-transfer character. Using first-principles calculations based on density functional theory and many-body perturbation theory, we compute the average electron-hole distance and quantify the degree of charge-transfer character within optical excitations in solid-state pentacene. We show that several low-energy singlet excitations are characterized by a weak overlap between electron and hole and an average electron-hole distance greater than 6 Å. Additionally, we show that the character of the lowest-lying singlet and triplet excitons is well-described with a simple analytic envelope function of the electron-hole distance.

Original languageEnglish (US)
Pages (from-to)2197-2201
Number of pages5
JournalJournal of Physical Chemistry Letters
Volume4
Issue number13
DOIs
StatePublished - Jul 3 2013

Keywords

  • charge-transfer exciton
  • electron-hole distribution
  • exciton wave function
  • many-body perturbation theory
  • organic crystals
  • organic photovoltaics
  • pentacene

ASJC Scopus subject areas

  • General Materials Science
  • Physical and Theoretical Chemistry

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