OLED Pixel-Defining Layer Inlets for Inkjet Printing Stability
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Solution Overview
Problem
Inkjet printing processes for organic light-emitting display devices face defects such as ink stains due to varying pitches of sub-pixels, leading to process inefficiencies and quality issues.
Innovation Solution
The design includes a pixel-defining layer with specific openings and inlets that allow for the dispensing of ink at a constant pitch, ensuring consistent formation of the intermediate layer between sub-pixels emitting the same wavelength, thereby stabilizing the inkjet printing process and minimizing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If inkjet printing is used to form the intermediate layer on sub-pixels with varying pitches, then the intermediate layer can be formed selectively on each sub-pixel, but the process deteriorates and causes ink stains due to the varying pitches
Solution Approach 1:
The pixel-defining layer is segmented to include both first openings (for exposing pixel electrodes) and second openings (for exposing substrate between sub-pixels). This segmentation allows the inkjet head to print at regular intervals through the second openings, eliminating the need to adapt to varying sub-pixel pitches while still achieving selective intermediate layer formation.
Solution Approach 2:
The second openings in the pixel-defining layer act as intermediary structures that facilitate constant-pitch inkjet printing. These openings provide fixed reference points for the inkjet head, serving as a mediator between the varying sub-pixel positions and the inkjet printing process, thereby ensuring process stability.
2Ease of manufacture
If the inkjet head dispenses ink at varying pitches to match sub-pixel positions, then selective deposition on each sub-pixel is achieved, but process defects such as ink stains occur
Solution Approach 1:
The pixel-defining layer is divided into first openings aligned with pixel electrodes and second openings positioned between sub-pixels. This segmentation enables the inkjet process to use second openings as stable reference points for dispensing, preventing ink from being deposited in incorrect locations and eliminating ink stains.
Solution Approach 2:
The pixel-defining layer with its pattern of first and second openings is formed in advance before the inkjet printing process. This preliminary structuring establishes fixed reference points that guide the inkjet head, ensuring that ink is deposited only where intended and preventing harmful ink stains before the printing process begins.
3Adaptability or versatility
If varying pitches are used for sub-pixels, then each sub-pixel can be individually addressed, but the inkjet printing process deteriorates and requires complex control
Solution Approach 1:
The pixel-defining layer is segmented into two types of openings: first openings that adapt to varying sub-pixel positions and second openings that provide constant reference points. This dual-segmentation approach maintains sub-pixel positioning flexibility while simplifying the inkjet printing process by providing stable reference points.
Solution Approach 2:
The pixel-defining layer performs multiple functions: first openings enable selective intermediate layer formation on pixel electrodes, while second openings provide universal constant-pitch reference points for the inkjet head. This multi-functionality allows the structure to accommodate varying sub-pixel positions without increasing process complexity.
Data Source
AI summary
An organic light-emitting display device is provided. The organic light-emitting display device includes a plurality of first electrodes, wherein each first electrode corresponds to a sub-pixel. The display device also includes a pixel-defining layer comprising a plurality of first openings exposing at least a portion of the first electrodes, and a plurality of inlets disposed on an upper surface of the pixel-defining layer. The display device further includes an intermediate layer disposed on the exposed portion of the first electrodes and the inlets, and an opposite electrode disposed on the intermediate layer and the pixel-defining layer, wherein the inlets are selectively disposed between adjacent sub-pixels emitting light of a same wavelength.