OLED Array Substrate Stepped Pixel Defining Layers
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Solution Overview
Problem
Existing OLED device manufacturing techniques face challenges in forming uniform pixel defining layers, particularly due to color mixing and poor moisture resistance, and are not suitable for large-scale production with high equipment investment and low material utilization.
Innovation Solution
An array substrate is designed with a stepped structure of inorganic and organic pixel defining layers, where the first opening is formed by vapor deposition and dry etching, and the second opening is created by inkjet printing, ensuring accurate layer formation and improved moisture barrier properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If one-time exposure development is used to form the pixel defining layer, then the manufacturing process is simple, but the pixel region has poor anti-moisture property and color mixing occurs
Solution Approach 1:
The pixel defining layer is divided into multiple sub-layers (first pixel defining layer and second pixel defining layer) with different functions. The first layer provides moisture barrier protection while the second layer defines the pixel pattern, separating the moisture protection function from the patterning function to solve both simplicity and reliability requirements
Solution Approach 2:
The pixel defining structure uses composite material composition with inorganic materials (such as silicon oxide, silicon nitride) for the first pixel defining layer to provide excellent moisture barrier properties, and organic photoresist materials for the second layer for easy patterning, combining advantages of different material types
2Manufacturing precision
If vacuum evaporation is used to form the organic electroluminescent layer, then the layer thickness is uniform, but equipment investment is high and material utilization rate is low
Solution Approach 1:
The patent replaces the vacuum evaporation mechanical deposition system with a solution-based coating system (spin coating or inkjet printing). The organic electroluminescent materials are dissolved in solvents and applied as solutions, eliminating the need for expensive vacuum evaporation equipment while achieving uniform layers through solution processing
Solution Approach 2:
The patent changes the physical state of material application from vapor phase (vacuum evaporation) to liquid phase (solution coating). By dissolving organic electroluminescent materials in appropriate solvents and controlling evaporation or printing parameters, uniform thin films are formed without requiring high-cost vacuum equipment
3Productivity
If inkjet printing is used to form the organic electroluminescent layer, then equipment cost is low and large-scale production is suitable, but the layer thickness is difficult to uniform
Solution Approach 1:
The pixel defining layers are formed in advance to create precise masks and patterns before the organic electroluminescent layer is deposited. This preliminary structuring guides the inkjet printing process, ensuring that material is deposited only in required areas with controlled thickness, solving both productivity and precision requirements
4Reliability
If inverted trapezoidal pixel defining layer structure is used, then short circuit and open circuit problems are avoided, but vapor deposition is difficult in the inverted trapezoidal region
Solution Approach 1:
The pixel defining structure is segmented into multiple layers with different cross-sectional shapes. The first layer has a trapezoidal cross-section optimized for vapor deposition, while the second layer has an inverted trapezoidal cross-section that prevents short circuits. This segmentation allows each layer to be optimized for its specific function without compromising the other
Solution Approach 2:
The patent transitions from a single-layer two-dimensional pattern to a multi-layer three-dimensional structure. By adding the vertical dimension with stacked layers having different geometries, the design simultaneously achieves good vapor deposition characteristics in the first layer and electrical isolation in the second layer, resolving the contradiction between manufacturability and reliability
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 approach effectively reduces color mixing and enhances the moisture barrier properties of the pixel region, enabling more efficient and cost-effective large-scale production of OLED devices.
Implementation Method 1
a first pixel defining layer which is an inorganic layer and disposed on the array layer
Implementation Method 2
a first opening extending through the first pixel defining layer
Data Source
AI summary
An array substrate, a method of manufacturing thereof, and a display device are provided. The array substrate includes a substrate, an array layer disposed on the substrate, an anode trace layer disposed on the array layer, a first pixel defining layer being an inorganic layer and disposed on the array layer, a first opening extending through the first pixel defining layer, a second pixel defining layer disposed on the first pixel defining layer, and a second opening extending through the second pixel defining layer. A projection of the first opening defined on the array layer completely falls within a projection of the second opening defined on the array layer. A light emitting region is defined by forming two pixel defining layers, so a color mixing problem is improved, and a pixel defining layer made of an inorganic material can improve a moisture barrier property of a pixel region.