jp512650g_si_001.pdf (7.47 MB)
Intra- to Intermolecular Singlet Fission
journal contribution
posted on 2015-01-22, 00:00 authored by M. Tuan Trinh, Yu Zhong, Qishui Chen, Theanne Schiros, Steffen Jockusch, Matthew
Y. Sfeir, Michael Steigerwald, Colin Nuckolls, Xiaoyang ZhuSinglet fission, the splitting
of one singlet into two triplets,
can potentially increase the efficiency of optoelectronic devices
beyond conventional limits. Among the singlet fission molecules discovered
to date, two mechanisms have emerged: intra- or intermolecular singlet
fission. Here we show a combined intra- to intermolecular singlet
fission mechanism in the model system of diphenyl-dicyano-oligoene
(DPDC). Excitation of DPDC to the first optically bright state leads
to the ultrafast formation of an intramolecular triplet pair, which
decays in 40 ps in the solution phase but can also split competitively
in 30 ps into two long-lived triplets (2×T1) on adjacent
molecules in solid films. These findings suggest a design principle
for efficient singlet fission: the independent tuning of singlet–triplet
pair coupling and triplet pair splitting from intra- and intermolecular
interactions, respectively.