OLED Pixel Definition Layer Incline for Light Transmittance

The patent transitions from a conventional planar cathode structure to a three-dimensional sloped cathode structure. The cathode is formed with a slope angle of 5-25 degrees relative to the substrate, creating an inclined surface that extends from the pixel center toward the pixel definition layer. This dimensional change allows the cathode to maintain adequate thickness for electrical continuity while reducing the effective thickness in the light emission path, thereby increasing light transmittance without compromising electrode reliability.

The patent implements local quality by creating a non-uniform cathode structure with varying thickness across the pixel region. The cathode has a slope angle of 5-25 degrees, being thicker at the edges near the pixel definition layer and thinner at the center toward the pixel opening. This gradient structure allows different regions of the cathode to serve different functions: the thinner central region improves luminescence efficiency and light transmittance, while the thicker edge regions maintain electrical continuity and facilitate precise color cast control through optimized material deposition in different zones.

The patent optimizes the slope angle parameter of the pixel definition layer to fall within the range of 5-25 degrees. This parameter change balances multiple requirements: angles less than 5 degrees would result in insufficient cathode thinning and reduced light transmittance, while angles greater than 25 degrees would create excessively steep slopes that are difficult to manufacture and may compromise cathode continuity. The selected parameter range enables effective light transmittance improvement while maintaining manufacturability through standard deposition and etching processes.