Organic Light-Emitting Display Pixel Definition Layer Grooves
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Solution Overview
Problem
High-resolution organic light-emitting displays face challenges in achieving high process yield and minimizing leakage current, which leads to color mixing defects due to the limitations of fine metal masks and the displacement of organic compound layers, especially in large-area displays.
Innovation Solution
The implementation of a planarization layer with a stopper and pixel definition layer having different etch selectivity, along with grooves in the pixel definition layer to control leakage current, and the use of inorganic materials like silicon oxide or nitride for the stopper to prevent etching errors and device deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a fine metal mask is used to pattern high-resolution pixels, then pixel definition is improved, but process yield deteriorates due to mask sag and displacement
Solution Approach 1:
The patent removes the fine metal mask from the patterning process entirely. Instead of using a mask to define pixels, the invention uses a pixel definition layer with contact holes that are formed by etching through the planarization layer, allowing the organic compound layer to be directly patterned without mask-based photolithography, thereby eliminating mask sag and displacement issues
Solution Approach 2:
The patent replaces the mechanical fine metal mask system with a chemical etching process. The pixel definition layer with its contact holes defines the pixel patterns through selective etching of the organic compound layer, substituting the mechanical mask approach with a chemistry-based patterning method that avoids physical mask limitations
2Manufacturing precision
If the organic compound layer is made thin for high resolution, then pixel density is improved, but leakage current increases causing color mixing
Solution Approach 1:
The patent introduces the pixel definition layer as an intermediary structure between the substrate and the organic compound layer. This layer with its contact holes serves as a mediator that defines pixel boundaries and prevents leakage current from spreading between adjacent pixels, thereby preventing color mixing while maintaining high pixel density
Solution Approach 2:
The patent segments the organic compound layer into discrete pixel regions defined by contact holes in the pixel definition layer. This segmentation isolates each pixel's organic compound material, preventing electrical leakage and color mixing between adjacent pixels even when the organic layer is thin for high resolution
3Area of stationary object
If a large-area fine metal mask is used for large displays, then display area is improved, but mask sag increases causing displacement defects
Solution Approach 1:
The patent removes the large-area fine metal mask from the manufacturing process. Instead of relying on a physical mask that sags under its own weight over large areas, the invention uses a pixel definition layer that is formed as a thin film deposited conformally across the entire display area, eliminating the mechanical support structure that causes sag
Solution Approach 2:
The patent employs a thin film pixel definition layer that is deposited conformally across the large display area. This thin film approach avoids the mechanical constraints of large rigid masks, allowing the pattern to be defined by the film deposition and subsequent etching processes rather than by a physically supported mask structure
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution effectively minimizes leakage current and prevents color mixing defects, enhancing the display quality and process yield by controlling the etching process and reducing the flow of leakage current, thereby improving the resolution and color reproduction of high-resolution organic light-emitting displays.
Implementation Method 1
The stopper and the pixel definition layer have different etch selectivity from each other. The stopper includes a material having an etching rate which is set lower than the etching rate of the pixel defining layer.
Implementation Method 2
An organic light-emitting display comprises pixels each having an organic light-emitting diode that converts electrical energy into light energy. The organic light-emitting diode comprises an anode, a cathode, and an organic compound layer situated between the anode and cathode. Holes and electrons are injected from the anode and cathode, respectively, and they recombine to form excitons, whereby the organic light-emitting display displays an image when the excitons fall from the excited state to the ground state.
Data Source
AI summary
An organic light-emitting display having pixels comprises a planarization layer disposed on transistors, first electrodes disposed on the planarization layer and individually allocated to the pixels, a stopper disposed on the planarization layer and placed between the first electrodes neighboring each other, and a pixel definition layer that has apertures exposing respectively at least a part of the first electrodes and grooves exposing at least a part of the stopper.