We present an antireflection structure consisted of irregular nanopillars to increase light extraction efficiency of flexible organic light-emitting devices. The nanopillars were made by imprinting the anodized aluminum oxide on polycarbonate substrates. The thermal viscosity effect formed the nanopillars with tapered shapes. Such nanopillars show excellent antireflection properties for a wide range of incident angles and wavelengths. The normal transmittance was improved from 85.5% to 95.9% for 150-nm-height nanopillars. The transmittance was greatly improved from 52.8% to 89.1% at 60° incident angle. With this antireflection structure, the device efficiency was improved 69% as compared to devices with flat substrates. Due to wide-angle antireflection, the image contrast ratio was also significantly improved.

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We present an antireflection structure consisted of irregular nanopillars to reduce the substrate surface reflection of OLED/OPV hybrid device, which both the luminous efficiency and energy conversion efficiency had great improvement. The nanopillars were made on flexible polycarbonate substrates by using nanoimprint method with anodized aluminum oxide template. The average reflectivity of the patterned polycarbonate substrate in visible wavelength was reduced to 3.3% in the optimized case. With the antireflection structure, the luminous intensity for OLED was improved 49.8% as compared to the device with flat substrates. The power conversion efficiency for OPV was improved from 0.48% to 0.55%, which had 14.6% enhancement at normal incidence.

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We demonstrated a highly efficient color conversion layers (CCLs) by using nanosphere arrays for white organic lightemitting diodes. The introduced periodical nanospheres not only help extract the confined light in devices, but also increase the effective light path to achieve more efficient color conversion. By applying the nanospheres patterned CCL on a PVK-based phosphorescent blue OLED, 137% color conversion ratio had been achieved, which was 2.68 times higher than flat CCL. The resulting luminous efficiency of white device with patterned CCL (20.97 cd/A, 1000 cd/m 2 ) was twice higher than the efficiency of the flat device (10.26 cd/A, 1000 cd/m 2 ).