| AVS 57th International Symposium & Exhibition | |
| Nanometer-scale Science and Technology | Wednesday Sessions |
| Session NS+EM+EN-WeA |
| Session: | Photonic and Plasmonic Materials and Devices |
| Presenter: | N.C. Erickson, University of Minnesota |
| Authors: | N.C. Erickson, University of Minnesota R.J. Holmes, University of Minnesota |
| Correspondent: | Click to Email |
We demonstrate efficient electrophosphorescence from devices comprised of a single organic active layer. High efficiency is realized by combining both hole- and electron-transporting host materials (HTM and ETM, respectively) into a single, graded composition emissive layer with the green emitter, fac-tris(2-phenylpyridine) iridium (III). The composition of the host-material is continuously graded to realize 100% HTM at the anode, and 100% ETM at the cathode. A peak external quantum efficiency of ηEQE=(19.3 ± 0.4) % is realized in the forward-viewing direction at a luminance level of 600 cd/m2, corresponding to a power efficiency of ηP =(66.5 ± 1.3) lm/W. This performance is similar to that realized in more conventional and complex, multi-layered structures. The graded composition of the structure balances electron and hole injection and transport leading to efficient exciton formation, permitting high efficiency using a single active layer. The graded composition architecture may be further utilized to realize simple, efficient organic light-emitting devices for use in display and lighting applications.