OLED Planarization Layer Structure to Prevent Contrast Loss and Dark Spots

The pixel defining layer is divided into two separate layers: a first transparent planarization layer and a second colored planarization layer. This segmentation allows each layer to perform its specific function independently - the first layer provides planarization and electrical connection without residues, while the second layer provides the coloring function to prevent contrast degradation without causing dark spots.

The harmful residues are extracted and eliminated by separating the coloring function from the planarization function. The first transparent planarization layer is formed without the colored material that causes residues, thus removing the source of dark spots while maintaining the necessary planarization and electrical connection functions.

The first transparent planarization layer and the second colored planarization layer are merged into an integrated structure where the first layer serves as both a planarization layer and a base for the second layer. This merging reduces process complexity by combining multiple functions into a unified layered structure rather than treating them as separate independent components.

The first transparent planarization layer performs multiple functions: it provides planarization for the underlying structure, serves as an insulating layer, provides electrical connection through contact holes, and acts as a base layer for the second colored planarization layer. This multi-functionality reduces the need for additional separate layers and processes.