We report spontaneously formed random corrugations as an efficient light extraction strategy in flexible organic light-emitting devices (OLEDs). The corrugations with directional randomness and broad distribution are spontaneously formed on the modified surface of SU-8 elastic film due to the mismatch of thermal expansion coefficients between the surface and bulk of SU-8. The topographic parameters of the random corrugations are desirably tunable by simply adjusting the annealing temperatures. The flexible OLEDs based on the random-corrugated SU-8 substrate demonstrate the improved light extraction characteristics in broadband, corresponding to the enhancements of 34% in luminance and 15.09% in current efficiency without directionality and spectral changes. The corrugated OLEDs also show high flexibility and mechanical stability without dramatical performance falloff under bending, folding as well as twisting.
