Role of Singlet and Triplet Excited States in the Oxygen-Mediated Photophysics and Photodegradation of Polyacenes

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dc.contributor.authorStuart, A.N.
dc.contributor.authorKee, T.W.
dc.contributor.authorHuang, D.M.
dc.date.issued2024
dc.description.abstractPolyacenes, such as tetracene and pentacene, are common model systems for the study of photophysical phenomena such as singlet fission (SF) and triplet fusion, processes which may lead to increased photovoltaic efficiencies. While they exhibit desirable photophysical properties, these materials are not photostable and convert to unwanted endoperoxides in the presence of oxygen and light, limiting their use in real-world applications. Not only does oxygen degrade polyacenes but also it can affect their photophysics, leading to both the sensitization and quenching of different excited states. In this study, we characterize the effect of oxygen on 5,12-bis(triisopropylsilylethynyl) tetracene (TIPS-Tn) and 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-Pn) using transient absorption spectroscopy, and show that oxygen can significantly influence the population of excited states, in particular enhancing the polyacene triplet population. We additionally combine the time-resolved excited-state dynamics with photodegradation studies to determine the predominant mechanism of photooxidation, which has previously been unclear. We find that both molecules photodegrade predominantly via singlet oxygen; however, for TIPS-Tn, this occurs through the triplet state, whereas for TIPS-Pn, degradation occurs through the excited singlet. The photodegradation of TIPS-Tn is thus enhanced by faster rates of SF, whereas SF in TIPS-Pn increases the molecule's photostability. This work has implications both for the design of new materials for next-generation photovoltaics that can avoid photooxidation and for the study of their photophysics in real-world environments.
dc.description.statementofresponsibilityAlexandra N. Stuart, Tak W. Kee, and David M. Huang
dc.identifier.citationJournal of the American Chemical Society, 2024; 146(3):2174-2186
dc.identifier.doi10.1021/jacs.3c12245
dc.identifier.issn0002-7863
dc.identifier.issn0002-7863
dc.identifier.orcidStuart, A.N. [0000-0002-3276-6196]
dc.identifier.orcidKee, T.W. [0000-0002-4907-4663]
dc.identifier.orcidHuang, D.M. [0000-0003-2048-4500]
dc.identifier.urihttps://hdl.handle.net/2440/141953
dc.language.isoen
dc.publisherAmerican Chemical Society
dc.relation.granthttp://purl.org/au-research/grants/arc/DP160103797
dc.relation.granthttp://purl.org/au-research/grants/arc/LE0989747
dc.relation.granthttp://purl.org/au-research/grants/arc/LE200100051
dc.rights© 2024 American Chemical Society
dc.source.urihttp://dx.doi.org/10.1021/jacs.3c12245
dc.subjectPolyacenes; photophysical phenomena
dc.titleRole of Singlet and Triplet Excited States in the Oxygen-Mediated Photophysics and Photodegradation of Polyacenes
dc.typeJournal article
pubs.publication-statusPublished

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