Corrugated organic light emitting diodes are fabricated on photonic crystal substrates patterned using UV nanoimprint lithography process at room-temperature and low-pressure. Forty-nine percentage enhancement of light extraction was achieved even with the very low corrugation depth of 50 nm. The power efficiency of the corrugated OLEDs was even further improved by 93% compared to the OLED with a planar structure. Finite difference time domain (FDTD) analyses indicated that the Bragg-reflection by the corrugated metallic mirror plays dominant role in the enhancement of extraction efficiency in the corrugated structure and extraction efficiency can be further improved if corrugation depth is increased to 100 nm. (C) 2009 Elsevier B. V. All rights reserved.