Fabrication of the Dispersed Hollow Polymer Scattering Layer for Enhancing the Light Out-Coupling of Organic Light-Emitting Diodes

A scattering layer is fabricated onto organic light emitting diodes (OLEDs) by using dispersed particles of cross-linked hollow polymers in a poly (methylmethacrylate) (PMMA) matrix to enhance the light extraction efficiency from OLEDs. The cross-linked hollow polymer particles were prepared by the organic-inorganic nanocomposite approach. First, silica nanoparticles of ca. 500nm in size were prepared, and then cross-linked polymer shells of poly (butyl methacrylate) were formed on the particles by dispersion polymerization. The HF solution was used to etch the core template. The hollow polymeric particles dispersed in the PMMA solution was spin-coated on a glass substrate. After fabricating the OLED, the current efficiency was improved by 18% with 10wt% content of hollow particles in the scattering layer, while it was improved by 8% with 30wt% content of the particles. The hollow polymer scattering layer showed improved optical properties since the hollow particles allow light transmission through their hollow inner part and reflect the light by their solid shell.