Double Bank Structure for Uniform OLED Layer Deposition
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Solution Overview
Problem
The challenge in organic light emitting display devices is the thickness non-uniformity of the light emitting layer formed through the solution process, leading to deteriorated display quality due to position-dependent thickness deviations and potential color mixing defects in high-resolution displays.
Innovation Solution
An organic light emitting display device with a double bank structure, featuring a substrate with a display area and non-display area, overcoat layer, first and second banks with specific openings, and an organic light emitting layer in these openings, which helps in uniform deposition and prevents color mixing by maintaining the hydrophilic and hydrophobic properties of the banks to ensure consistent layer thickness and emission area design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a light emitting layer is formed through the solution process, then material use rate and thermal stability are improved, but thickness uniformity deteriorates due to position-dependent thickness deviations
Solution Approach 1:
The bank structure is divided into a first bank and a second bank, where the first bank has first openings exposing first electrodes and the second bank has second openings exposing the first electrodes. This segmentation allows different regions to control material deposition independently, improving thickness uniformity across the display area while maintaining the solution process benefits
Solution Approach 2:
The first bank and second bank are configured with different opening patterns and positions to provide localized control over the organic light emitting material deposition. The first openings and second openings are strategically positioned to ensure uniform thickness in different regions, addressing the thickness deviation problem while preserving the high material use rate of the solution process
2Manufacturing precision
If a mask is used for patterning sub-pixels, then deposition precision is improved, but mask sag occurs in large-area devices causing non-deposition defects
Solution Approach 1:
The mask is completely removed from the process, and patterning is achieved through the bank structure with strategically positioned openings. The first bank and second bank together define the sub-pixel patterns without requiring a physical mask, eliminating mask sag issues while maintaining patterning precision through the engineered opening configurations
Solution Approach 2:
The bank structure serves as an intermediary element that replaces the mask function. The first bank and second bank with their respective openings act as a mediator to achieve precise patterning of the organic light emitting layer without direct mask contact, preventing mask-related defects while maintaining deposition completeness
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
The double bank structure enhances the uniformity of the organic light emitting layer thickness, reduces display quality deterioration, and prevents color mixing defects, thereby improving the overall performance and design flexibility of the display device.
Implementation Method 1
an organic light emitting layer disposed in each of the second openings, the third openings and the fourth openings
Implementation Method 2
maintaining the hydrophilic and hydrophobic properties of the banks to ensure consistent layer thickness
Data Source
AI summary
An organic light emitting display device includes a substrate including a display area and a non-display area, the display area including a plurality of sub-pixels; an overcoat layer disposed on the substrate; first electrodes disposed on the overcoat layer and in the sub-pixels; a first bank disposed in the display area and the non-display area and including first openings, the first openings respectively exposing the first electrodes; a second bank disposed on the first bank and including second openings in the display area, third openings in the non-display area and fourth openings, the second openings exposing the plurality of first electrodes arranged in the display area, the third openings exposing the first openings arranged in the non-display area, and the fourth openings connecting the second openings and the third openings; and an organic light emitting layer disposed in each of the second openings, the third openings and the fourth openings.