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Extraction efficiency of organic light emitting diodes with two-dimensional photonic quasi-crystal structure

In this study, we inserted a two-dimensional (2D) photonic quasi-crystal (PQC) structure into the OLED devices for light extraction. The 2-D PQC structure was fabricated on the glass substrate by simple way of nanoimprinting. To decrease the roughness of the substrate, we used the polymer layer to cover and planarize the PQC structure on the glass substrate, and then, we fabricated the internally planarized green OLEDs. The internally planarized green OLEDs show a great enhancements of the external quantum efficiency by 20.0% compared to the normal green OLEDs. The results can attribute to the light out-coupling effect in the OLED via the 2-D PQC structure to release the generated light trapped in the wave guide mode due to the total internal reflection (TIR).