Morphology- and crystal packing-dependent singlet fission and photodegradation in functionalized tetracene crystals and films

Winston T. Goldthwaite, Evan Lambertson, Madalyn Gragg, Dean Windemuller, John E. Anthony, Tim J. Zuehlsdorff, Oksana Ostroverkhova

Research output: Contribution to journalArticlepeer-review

Abstract

Singlet fission (SF) is a charge carrier multiplication process that has potential for improving the performance of (opto)electronic devices from the conversion of one singlet exciton S1 into two triplet excitons T1 via a spin-entangled triplet pair state 1(TT). This process depends highly on molecular packing and morphology, both for the generation and dissociation of 1(TT) states. Many benchmark SF materials, such as acenes, are also prone to photodegradation reactions, such as endoperoxide (EPO) formation and photodimerization, which inhibit realization of SF devices. In this paper, we compare functionalized tetracenes R-Tc with two packing motifs: “slip-stack” packing in R = TES, TMS, and tBu and “gamma” packing in R = TBDMS to determine the effects of morphology on SF as well as on photodegradation using a combination of temperature and magnetic field dependent spectroscopy, kinetic modeling, and time-dependent density functional theory. We find that both “slip-stack” and “gamma” packing support SF with high T1 yield at room temperature (up to 191% and 181%, respectively), but “slip-stack” is considerably more advantageous at low temperatures ( < 150 K). In addition, each packing structure has a distinct emissive relaxation pathway competitive to SF, while the states involved in the SF itself are dark. The “gamma” packing has superior photostability, both in regards to EPO formation and photodimerization. The results indicate that the trade-off between SF efficiency and photostability can be overcome with material design, emphasize the importance of considering both photophysical and photochemical properties, and inform efforts to develop optimal SF materials for (opto)electronic applications.

Original languageEnglish
Article number194712
JournalJournal of Chemical Physics
Volume161
Issue number19
DOIs
StatePublished - Nov 21 2024

Bibliographical note

Publisher Copyright:
© 2024 Author(s).

ASJC Scopus subject areas

  • General Physics and Astronomy
  • Physical and Theoretical Chemistry

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