Evaluation of the absolute photoluminescence quantum yields of molecularly doped organic composite films and the electroluminescence efficiencies of molecular light-emitting devices containing olig

Gary P. Kushto; Ian G. Hill; Ullrich Mitschke; Peter Baeuerle; Zakya H. Kafafi

doi:10.1117/12.416928

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2 February 2001 Evaluation of the absolute photoluminescence quantum yields of molecularly doped organic composite films and the electroluminescence efficiencies of molecular light-emitting devices containing oligoheterocycles as efficient emission centers

Gary P. Kushto, Ian G. Hill, Ullrich Mitschke, Peter Baeuerle, Zakya H. Kafafi

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Proceedings Volume 4105, Organic Light-Emitting Materials and Devices IV; (2001) https://doi.org/10.1117/12.416928
Event: International Symposium on Optical Science and Technology, 2000, San Diego, CA, United States

Abstract

The absolute photoluminescence quantum yields ((Phi) _PL) of three end-capped oligothiophene derivatives dispersed in N,N'-((alpha) -naphthyl)-N,N'-diphenyl-1,1'-biphenyl ((alpha) -NPD) have been evaluated and the most efficient of the emitters was used as a dopant in molecular organic LEDs. Composite films of 2,5-bis [5-(4,5,6,7- tetrahydrobenzo[b]thien-2-yl) thien-2-yl]-furan (EC5FUR); 2,5-bis [5-(4,5,6,7- tetrahydrobenzo[b]thien-2-yl) thien-2-yl]-oxazole (EC5OXZ) and 2,5-bis [5-(4,5,6,7- tetrahydrobenzo[b]thien-2-yl)thien-2-yl]-1,3,4- oxadiazole (EC5OXD) doped into (alpha) -NPD were found to have (Phi) _PL values of 78, 62 and 28%, respectively. MOLED devices were fabricated using an EC5FUR/(alpha) -NPD composite as the emitting layer and the external quantum efficiencies ((eta) _EL) of these devices were evaluated. The results of the device characterization show that the inclusion of EC5FUR in the NPD hole transport layer increases the device (eta) _EL to 1.45% at a current density of 10 mA/cm². In addition, the concentration dependence of the (eta) _EL on the EC5FUR dopant in certain device structures when considered in conjunction with the current results of ultraviolet photoemission spectroscopic experiments suggests that this dopant species may be acting as both a hole and electron trap in the (alpha) -NPD host.

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Gary P. Kushto, Ian G. Hill, Ullrich Mitschke, Peter Baeuerle, and Zakya H. Kafafi "Evaluation of the absolute photoluminescence quantum yields of molecularly doped organic composite films and the electroluminescence efficiencies of molecular light-emitting devices containing oligoheterocycles as efficient emission centers", Proc. SPIE 4105, Organic Light-Emitting Materials and Devices IV, (2 February 2001); https://doi.org/10.1117/12.416928

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