Polymer grating imbedded organic light emitting diodes with improved out-coupling efficiency

Organic light emitting diodes with enhanced external light coupling efficiency are demonstrated by incorporating a polymeric diffraction grating fabricated directly on top of the indium tin-oxide (ITO) electrode. Compared to the previous inorganic diffraction gratings fabricated under the ITO electrode, the polymer grating prepared by convenient lithography facilitates the fabrication process and provides good compatibility with conventional production facilities. In spite of the reduction in the emitting area, the luminance efficiency is improved by 72% by imbedding the polymer grating. The strong scattering of the guided mode enables the device to have negligible wavelength dispersion. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3491286]