OLED Cathode Segmentation for Brightness Uniformity

The invention divides the cathode into multiple segments: a transparent oxide cathode layer (first cathode) and a metal cathode layer (second cathode) arranged in parallel. This segmentation allows each layer to contribute differently - the TCO layer provides transparency while the metal layer provides low resistance, solving the contradiction between light transmittance and brightness uniformity.

The invention uses a composite cathode structure combining transparent oxide materials (such as ITO, IZO, or IFS) with metal materials (such as Al, Ag, or Mo). This composite structure integrates the advantages of both materials: the TCO provides optical transparency while the metal provides electrical conductivity, resolving the contradiction between light transmittance and sheet resistance.

The invention applies different properties to different regions of the common layers. By forming protrusions at the interval regions between sub-pixels, the patent creates local structural variations that prevent lateral current leakage in those specific areas while maintaining the overall simplicity of the open mask fabrication process. This local modification eliminates cross-color phenomenon without complicating the manufacturing process.

The protrusions are formed in advance during the fabrication process, before the light-emitting layers are deposited. This preliminary action of creating the protrusion structure prevents lateral current leakage from occurring in the first place, rather than attempting to correct it later. The protrusions are formed as part of the pixel definition layer or buffer layer, ensuring current isolation before subsequent layers are added.