OLED Pixel Demarcation Layer Ink Overflow Control
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Solution Overview
Problem
The instability of coating devices in strip coating processes for solution-processed OLEDs leads to ink overflow at the beginning of the coating process, limiting their application in display technology.
Innovation Solution
A pixel demarcation layer with a first sub-layer and a second sub-layer, where the second sub-layer includes openings with a second area in the edge area acting as an initiating terminal to store excess ink, preventing overflow and enhancing uniformity by reducing ink evaporation speed differences between the edge and center.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If strip coating is used for solution-processed OLED, then productivity and coating performance are improved, but ink overflow occurs at the beginning of the coating process due to coating device instability
Solution Approach 1:
The patent introduces a preliminary coating region before the actual display area, where the coating head performs initial coating operations. This preliminary action allows the coating device to stabilize its coating characteristics before reaching the display region, preventing ink overflow at the beginning of the coating process while maintaining high productivity through continuous coating operation.
2Manufacturing precision
If coating process starts directly in display area, then manufacturing precision is maintained, but ink overflow occurs due to unstable coating device at initiating terminal
Solution Approach 1:
The patent segments the coating area into two distinct regions: a preliminary coating region and a display area. The preliminary coating region serves as a buffer zone where unstable initial coating occurs without affecting the display quality. This segmentation isolates the harmful ink overflow to a non-critical area while ensuring manufacturing precision in the display region.
Solution Approach 2:
The preliminary coating region acts as an intermediary zone between the coating head and the display area. It mediates the transition from unstable initial coating to stable display-area coating, allowing the coating device to establish consistent coating parameters before depositing material in the critical display region.
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 solution effectively alleviates ink overflow and improves the uniformity of the organic light-emitting functional layer, enhancing the productivity and performance of OLEDs.
Implementation Method 1
Each of the second openings further includes a second area positioned in the edge area and configured to provide an initiating terminal from which the first area corresponding to the second area is coated with the organic light-emitting material
Implementation Method 2
Currently, there are two methods for fabricating the organic light-emitting functional layer, including vacuum evaporation and solution processing. As compared with the organic light-emitting functional layer fabricated by means of vacuum evaporation, the organic light-emitting functional layer fabricated by means of solution processing exhibits better coating performance for the anode electrode layer
Data Source
AI summary
A pixel demarcation layer includes a first pixel demarcation sub-layer and a second pixel demarcation sub-layer stacked on the first pixel demarcation sub-layer. The pixel demarcation layer is divided into a display area and an edge area located outside the display area. The first pixel demarcation sub-layer includes a plurality of first openings positioned within the display area each corresponding to a light-emitting region of a respective sub-pixel unit. The second pixel demarcation sub-layer includes a plurality of second openings each coated with an organic light-emitting material. Each of the second openings includes a first area positioned in the display area and corresponding to a set of the first openings. Each of the second openings also includes a second area positioned in the edge area and configured to provide an initiating terminal from which the first area corresponding to the second area is coated with the organic light-emitting material.