Organic light-emitting devices integrated with internal scattering layers for enhancing optical out-coupling

Abstract— In this work, studies on organic light-emitting devices (OLEDs) incorporating nanoparticle-based nanocomposite scattering layers as the internal extraction structures (i.e., between the substrate and the OLED structure) were concluded. By adjusting the nanoparticle sizes and concentrations, the optical properties (optical scattering and integrated transmittance) of the nanocomposite scattering layers can be widely tuned. With appropriate compositions, nanoparticle-based nanocomposite scattering layers with strong optical scattering, high integrated transmittance, and yet enough flatness for device integration can be obtained. The use of such nanocomposite internal scattering layers provides a convenient and effective approach for simultaneously achieving large efficiency enhancement (1.96× for quantum efficiency and 2.04× for cd/A efficiency) and improving viewing characteristics (more stable colors and emission patterns over angles). The fabrication of nanoparticle-based nanocomposite scattering films is based on solution-processing, which is relatively simple and convenient. These features may make it highly attractive for various OLED applications and mass production.