| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1267608 | Organic Electronics | 2011 | 6 Pages |
The orientation distribution of the emissive sites in a phosphorescent Organic LED has been measured utilizing two independent optical methods. In contradiction to common expectations we find a clearly non-isotropic, predominantly parallel emitter orientation in the well-known triplet emitting guest–host system of Ir(MDQ)2(acac) blended in an α-NPD matrix. This result emphasizes the necessity of more sophisticated assumptions on active emitter properties in quantitative optical OLED analysis, and demonstrates a highly promising approach for OLED efficiency optimization.
Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► OLED triplet emitter Ir(MDQ)2(acac) blended in α-NPD matrix is studied. ► Polarized emission patterns are analyzed under electrical and optical excitation. ► Unexpected non-isotropic, mainly parallel emitter orientation is found. ► Parallel emitters increase outcoupling efficiency by ∼50% compared to isotropic case. ► Promising approach for efficiency enhancement of phosphorescent guest–host systems is revealed.
