1. Efficient polarized light-emitting diodes utilizing ultrathin photoaddressable alignment layers
- Author
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Heinz-Georg Nothofer, R. Güntner, Rainer Hagen, Ullrich Scherf, Dieter Neher, X. H. Yang, Serguei Kostromine, and S. Lucht
- Subjects
chemistry.chemical_classification ,Brightness ,Materials science ,Physics and Astronomy (miscellaneous) ,business.industry ,Polymer ,Thermotropic crystal ,law.invention ,Polyfluorene ,chemistry.chemical_compound ,Optics ,chemistry ,law ,Optoelectronics ,business ,Absorption (electromagnetic radiation) ,Layer (electronics) ,Light-emitting diode ,Diode - Abstract
We demonstrate that an ultrathin photoaddressable polymer (PAP) layer with a thickness as small as 5 nm can be utilized for the monodomain alignment of thermotropic liquid crystalline polyfluorene. The optical anisotropies in absorption and emission are found to be independent of the PAP layer thickness within a range of 5 to 30 nm. On the other hand, decreasing the PAP layer thickness greatly improves the performance of polarized blue light-emitting diodes: With a PAP layer thickness of only 10 nm, the device turns on at 5 V and reaches a brightness of 100 cd/m2 at 8 V with an efficiency of 0.66 cd/A.
- Published
- 2002