Electroluminescent Display Bankless Structure Aperture Ratio
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Solution Overview
Problem
Related art electroluminescent displays face challenges in achieving high aperture ratio and ultra-high resolution due to current leakage from organic light emitting diodes, necessitating improvements in both light emission efficiency and electrical characteristics.
Innovation Solution
The proposed electroluminescent display employs a bankless structure with a sacrificial layer and separation layer to define subpixel emission areas, forming a lower electrode layer with a tapered edge and pattern holes to reduce current leakage and enhance aperture ratio, while maintaining efficient manufacturing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a conventional structure with bank layers is used to define subpixel emission areas, then the manufacturing process is simpler, but the aperture ratio is reduced and current leakage increases
Solution Approach 1:
The patent removes the bank layer structure entirely and replaces it with a sacrificial layer that is completely removed after defining the emission area. This extraction of the bank layer eliminates the aperture ratio reduction caused by bank structures while maintaining the ability to define subpixel emission areas through the sacrificial layer pattern and etching process
Solution Approach 2:
The sacrificial layer is formed and patterned beforehand to define the emission area boundaries before the actual electrode and emission layer deposition. This preliminary action allows for precise definition of the emission area without requiring physical bank structures, thereby increasing aperture ratio while maintaining manufacturing feasibility
2Area of stationary object
If the emission area is enlarged to improve aperture ratio, then the light emission efficiency increases, but current leakage between subpixels increases
Solution Approach 1:
The patent uses the sacrificial layer pattern to segment and define discrete emission areas for each subpixel. The sacrificial layer acts as a mask that is removed to create isolated emission regions, ensuring that enlarged emission areas remain electrically isolated and prevent current leakage between adjacent subpixels
Solution Approach 2:
The lower electrode layer with its tapered edge structure serves as an intermediary element that bridges the emission area enlargement and current leakage prevention. The tapered geometry provides a transition zone that maintains electrical isolation while allowing the emission area to expand, thus preventing direct contact between adjacent subpixel emission regions
3Area of stationary object
If the aperture ratio is increased to achieve ultra-high resolution, then the display quality improves, but the light emitting diode structure becomes more complex
Solution Approach 1:
The patent changes the geometric parameters of the lower electrode layer by introducing a tapered edge structure. This parameter change allows the emission area to be enlarged and aperture ratio to be increased while the tapered geometry inherently provides electrical isolation, thus achieving ultra-high resolution without proportionally increasing the light emitting diode structure complexity
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 configuration significantly improves the aperture ratio and reduces current leakage, enabling the achievement of ultra-high resolution and excellent electrical characteristics in the electroluminescent display.
Implementation Method 1
An electroluminescent display can display an image through a light emitting operation of light emitting diodes of subpixels
Data Source
AI summary
An electroluminescent display includes a lower substrate having a display area with subpixel emission areas defined in the display area; an electrode layer on the lower substrate; a planarization layer formed on the lower substrate such that holes are formed in the planarization layer with each hole being adjacent to a respective one of the subpixel emission areas; lower electrode layer in the respective subpixel emission area; a sacrificial layer surrounding the subpixel emission area and absent at an area having the lower electrode layer; an organic emission layer on the lower electrode layer; and an upper electrode layer on the organic emission layer.