Enhancement of light extraction from organic light-emitting diodes with two-dimensional hexagonally nanoimprinted periodic structures using sequential surface relief grating

Electric characteristics of organic light-emitting diodes (OLEDs) with two-dimensional hexagonally nanoimprinted periodic structures were investigated, and enhanced light extraction from this device was confirmed. A master mold was fabricated from an azobenzene polymer thin film patterned by sequential surface relief grating formation into a three-directional structure. The device shows a higher current density and a higher current efficiency, although leakage current is also higher than that of a device without periodic structures. These results are caused by the extraction of diffracted light from waveguided and substrate-guided light even when incident light has larger angles than the critical angle for total reflection.