Enhancement of light extraction of organic light emitting diodes with photonic quasi-crystal structures by UV nanoimprint lithography process

We demonstrate a method to increase the efficiency of blue and green organic light emitting diodes by a factor of up to 53.9 and 28.3 % when the device brightness was 1000 cd/m(2). By fabricating the organic light emitting diodes on top of a planarization 12-fold photonic quasi-crystal microstructure, the 12-fold photonic quasi-crystal microstructure was fabricated on the glass substrate by simple way of UV nanoimprint lithography process, and to decrease the roughness of the substrate, we used the high index filling layer to cover and planarize the photonic quasi-crystal structure. The photonic quasi-crystal microstructure released the light trapped in the wave guide mode, and it is found that photonic quasi-crystal microstructure can overcome the total internal reflection; we attribute that the photonic quasi-crystal microstructure could be integrated into organic light emitting diodes to tremendously enhance the emission efficiency.