Transient electroluminescence dynamics in small molecular organic light-emitting diodes
Intriguing electroluminescence (EL) spikes, following a voltage pulse applied to small molecular OLEDs, are discussed, elucidating carrier and exciton quenching dynamics and their relation to device structure. At low temperatures, all devices exhibit spikes at {approx} 70-300 ns and {mu}s-long tails. At 295 K only those with a hole injection barrier, carrier-trapping guest-host emitting layer, and no strong hole-blocking layer exhibit the spikes. They narrow and appear earlier under post-pulse reverse bias. The spikes and tails are in agreement with a revised model of recombination of correlated charge pairs (CCPs) and initially unpaired charges. Decreased post-pulse field-induced dissociative quenching of singlet excitons and CCPs, and possibly increased post-pulse current of holes that 'turn back' toward the recombination zone after having drifted beyond it are suspected to cause the spikes amplitude, which exceeds the dc EL.
- Research Organization:
- Ames Laboratory (AMES), Ames, IA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- AC02-07CH11358
- OSTI ID:
- 1024633
- Report Number(s):
- IS-J 7577
- Journal Information:
- Applied Physics Letters, Journal Name: Applied Physics Letters Journal Issue: 11 Vol. 97; ISSN 1077-3118
- Country of Publication:
- United States
- Language:
- English
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