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Single-step triplet-triplet annihilation: An intrinsic limit for the high brightness efficiency of phosphorescent organic light emitting diodes

: Staroske, W.; Pfeiffer, M.; Leo, K.; Hoffmann, M.


Physical review letters 98 (2007), No.19, Art. 197402
ISSN: 0031-9007
ISSN: 1079-7114
Journal Article
Fraunhofer IPMS ()

We investigate triplet-triplet annihilation in molecular host-guest systems where triplets are localized on spatially separated guest molecules. Our results indicate that the dominant mechanism of annihilation is single-step long-range (Förster-type) energy transfer between two excited guests. This mechanism leads to a fundamental limit for the efficiency of phosphorescent organic light emitting diodes at high luminance. Our model is confirmed by photoluminescence decay experiments on 2,3,7,8,12,13,17,18-octaethylporphine platinum as guest in a host matrix of 4,4-N,N-dicarbazole- biphenyl.