Organic EL Display Light Extraction via Insulation Film Curvature

The patent applies curvature by forming convex and concave portions on the insulation film surface. The convex portions have curved top surfaces with radii of curvature between 1-10 μm, and the concave portions have curved bottom surfaces. This curvature structure disrupts wave guiding of light within the organic EL layer, enabling light extraction at angles that would otherwise be trapped, thereby improving the light extraction ratio from 20% to over 50% while maintaining manufacturing simplicity through standard photolithography and etching processes

The patent transitions from a two-dimensional flat insulation film to a three-dimensional structured film with convex and concave portions. The convex portions protrude toward the organic EL layer by 1-10 μm, and concave portions recess by 1-10 μm, creating vertical dimensionality that provides additional light extraction pathways. This dimensional change allows light to escape at multiple angles and positions, significantly improving extraction efficiency without complicating the manufacturing process

The patent segments the light extraction function by creating multiple discrete convex portions within each pixel region, with each convex portion acting as an independent light extraction point. The convex portions are arranged in arrays with pitches of 5-20 μm, providing numerous localized extraction sites that improve overall light output without requiring larger shielding layers. This segmentation allows the aperture ratio to remain high (70-90%) while still preventing color mixing through the insulating effect of the convex structures

The patent applies local quality by concentrating light extraction enhancement at specific locations (convex portions) rather than uniformly across the entire pixel area. The convex portions are strategically positioned to maximize light extraction while the concave portions between them provide optical isolation. This localized approach prevents color mixing at pixel boundaries while maintaining high aperture ratios, as the light extraction function is performed only at discrete convex sites rather than requiring broad shielding layers

The patent uses simple spherical or hemispherical convex portions with radii of curvature between 1-10 μm, formed using standard photolithography and etching processes. These curved surfaces provide sufficient light extraction enhancement through refraction and scattering effects without requiring complex diffraction grating patterns. The curvature is achieved through conventional semiconductor manufacturing techniques, avoiding the need for specialized uneven-shaped grating fabrication while still improving light extraction ratio from 20% to over 50%

The patent employs a manufacturing approach using standard, widely-available photolithography and etching processes that are already part of conventional OLED fabrication lines. The convex and concave portions are formed using simple photoresist coating, patterning, and etching steps that can be performed with existing equipment. This avoids the need for expensive specialized manufacturing processes required for complex diffraction gratings, making the solution cost-effective and easily integrable into current production