Wave Function Based Analysis of Dynamics versus Yield of Free Triplets in Intramolecular Singlet Fission

Rafi Chesler, Souratosh Khan, Sumit Mazumdar

Research output: Contribution to journalArticlepeer-review

Abstract

Experiments in several intramolecular singlet fission materials have indicated that the triplet-triplet spin biexciton has a much longer lifetime than believed until recently, opening up loss mechanisms that can annihilate the biexciton prior to its dissociation to free triplets. We have performed many-body calculations of excited state wave functions of hypothetical phenylene-linked anthracene molecules to better understand linker-dependent behavior of dimers of larger acenes being investigated as potential singlet fission candidates. The calculations reveal unanticipated features that we show carry over to the real covalently linked pentacene dimers. Dissociation of the correlated triplet-triplet spin biexciton and free triplet generation may be difficult in acene dimers where the formation of the triplet-triplet spin biexciton is truly ultrafast. Conversely, relatively slower biexciton formation may indicate smaller spin biexciton binding energy and greater yield of free triplets. Currently available experimental results appear to support this conclusion. Whether or not the two distinct behaviors are consequences of distinct mechanisms of triplet-triplet generation from the optical singlet is an interesting theoretical question.

Original languageEnglish (US)
Pages (from-to)10091-10099
Number of pages9
JournalJournal of Physical Chemistry A
Volume124
Issue number49
DOIs
StatePublished - Dec 10 2020

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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