Triplet exciton dynamics in rubrene single crystals

The decay of the photoluminescence excited in rubrene single crystals by picosecond pulses is measured over 7 orders of magnitude and more than 4 time decades. We identify the typical decay dynamics due to triplet-triplet interaction. We show that singlet exciton fission and triplet fusion quantum yields in rubrene are both very large, and we directly determine a triplet exciton lifetime of 100 +/- 20 mu s, which explains the delayed buildup of a large photocurrent that has been reported earlier for low excitation densities.