Random nano-structures as light extraction functionals for organic light-emitting diode applications

• Using dewetted Ag droplets, we have fabricated a random scattering layer (RSL) and applied it as an OLED light extraction structure.
• OLEDs with the RSL showed more that 50% improvement in the external quantum efficiency and luminance efficacy due to the scattering effect.
• The RSL is effective way to improve the overall performance of OLEDs.

In this study, we demonstrated a nano-structured random scattering layer (RSL) as an internal light extraction method to improve the light extraction efficiency of organic light-emitting diodes (OLEDs). Using dewetted Ag droplets as a hard mask, we textured the glass surface to have a scattering layer of the random structure. OLEDs equipped with the RSL showed more that 50% improvement in the external quantum efficiency (EQE) and luminance efficacy (LE) compared to OLEDs without the RSL. This improvement can be understood by the scattering effect which reduces the optical loss at wave-guided modes. Also, by combining the RSL and an external light extraction micro-lens array (MLA), it was possible to achieve further improvements of 105.8% and 92.06% in the EQE and the LE, respectively.

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