Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10411642 | Solid-State Electronics | 2011 | 5 Pages |
Abstract
Transient electroluminescence (EL) was used to measure the delay between the excitation pulse and onset of emission in OLEDs based on phosphorescent bis[3,5-bis(2-pyridyl)-1,2,4-triazolato] platinum(ÎÎ) doped into 4,4â²-bis(carbazol-9-yl) triphenylamine (CBP), from which an electron mobility of 3.2Â ÃÂ 10â6Â cm2/VÂ s was approximated. Delayed recombination was observed after the drive pulse had been removed and based on its dependence on frequency and duty cycle, ascribed to trapping and de-trapping processes associated with disorder-induced carrier localization at the interface between the emissive layer and electron blocker. The data suggests that the exciton recombination zone is at, or close to the interface between the emissive layer and electron blocker. Despite the charge trapping effects, a peak power efficiency of 24Â lm/W and peak external quantum efficiency of 10.64% were obtained. Mechanisms for the electroluminescence and delayed recombination are proposed.
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Authors
Ming-Te Lin, Minghang Li, Wei-Hsuan Chen, Mohammad A. Omary, Nigel D. Shepherd,