Endothermic singlet fission is hindered by excimer formation

Cameron B. Dover, Joseph K. Gallaher, Laszlo Frazer, Patrick C. Tapping, Anthony J. Petty, Maxwell J. Crossley, John E. Anthony, Tak W. Kee, Timothy W. Schmidt

Research output: Contribution to journalArticleResearchpeer-review

125 Citations (Scopus)

Abstract

Singlet fission is a process whereby two triplet excitons can be produced from one photon, potentially increasing the efficiency of photovoltaic devices. Endothermic singlet fission is desired for a maximum energy-conversion efficiency, and such systems have been considered to form an excimer-like state with multiexcitonic character prior to the appearance of triplets. However, the role of the excimer as an intermediate has, until now, been unclear. Here we show, using 5,12-bis((triisopropylsilyl)ethynyl)tetracene in solution as a prototypical example, that, rather than acting as an intermediate, the excimer serves to trap excited states to the detriment of singlet-fission yield. We clearly demonstrate that singlet fission and its conjugate process, triplet-triplet annihilation, occur at a longer intermolecular distance than an excimer intermediate would impute. These results establish that an endothermic singlet-fission material must be designed to avoid excimer formation, thus allowing singlet fission to reach its full potential in enhancing photovoltaic energy conversion.

Original languageEnglish
Pages (from-to)305-310
Number of pages6
JournalNature Chemistry
Volume10
Issue number3
DOIs
Publication statusPublished - 1 Mar 2018
Externally publishedYes

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