Organic Light-Emitting Diode Pixel Electrode Positioning for Luminance Uniformity
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Solution Overview
Problem
Conventional organic light-emitting display devices face challenges in achieving uniform luminance due to difficulties in forming functional layers with consistent thickness using the inkjet method, leading to luminance unevenness in the light-emitting region.
Innovation Solution
The display device incorporates a novel structure with a pixel-defining layer and barrier ribs to partition the light-emitting regions into distinct areas, ensuring the pixel and common electrodes are positioned on opposite inner side surfaces, and functional layers are formed with constant thicknesses equal to or greater than the barrier rib height, allowing for uniform organic light-emitting portion coverage across both areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If functional layers are formed by inkjet method in conventional stacked structure, then manufacturing flexibility is improved, but manufacturing precision deteriorates due to non-uniform thickness
Solution Approach 1:
The light-emitting region is divided into first and second areas by a barrier rib, with electrodes and functional layers selectively positioned in each area. This segmentation allows independent control of inkjet printing parameters for each region, enabling uniform thickness formation despite surface tension and drying speed variations.
Solution Approach 2:
The barrier rib is formed in advance to define the first and second areas before functional layers are deposited. This preliminary structuring establishes reference surfaces at predetermined heights, guiding subsequent inkjet printing to achieve constant thickness functional layers that extend uniformly across both areas.
2Device complexity
If functional layers are formed by inkjet method, then device complexity is reduced, but luminance uniformity deteriorates due to drying speed differences between central and outer portions
Solution Approach 1:
Different regions (first and second areas) are assigned different functional layers and electrode configurations based on local requirements. The barrier rib creates distinct zones where inkjet printing parameters can be optimized locally, ensuring uniform drying and thickness control in each area while maintaining overall device simplicity.
3Ease of manufacture
If functional layers are formed by inkjet method, then ease of manufacture is improved, but manufacturing precision deteriorates due to surface tension differences between ink and insulating layer
Solution Approach 1:
The light-emitting region is divided into first and second areas by a barrier rib, with electrodes and functional layers selectively positioned in each area. This segmentation allows independent control of inkjet printing parameters for each region, enabling uniform thickness formation despite surface tension and drying speed variations.
Solution Approach 2:
The barrier rib is formed in advance to define the first and second areas before functional layers are deposited. This preliminary structuring establishes reference surfaces at predetermined heights, guiding subsequent inkjet printing to achieve constant thickness functional layers that extend uniformly across both areas.
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 enhances luminance uniformity across the light-emitting regions by ensuring consistent thickness and separation of functional layers, improving the overall performance of the organic light-emitting devices.
Implementation Method 1
emits light as excitons generated by combining holes and electrons supplied from the pair of electrodes in the organic emission layer falls from an exited state to a ground state
Data Source
AI summary
A display substrate includes: a pixel-defining layer located on the display substrate and including a plurality of light-emitting regions; and a plurality of light-emitting devices located in the plurality of light-emitting regions, respectively, wherein each of the plurality of light-emitting devices includes a pixel electrode, a common electrode, and an organic light-emitting portion between the pixel electrode and the common electrode, wherein the pixel-defining layer includes a first inner side surface and a second inner side surface facing each other in each of the plurality of light-emitting regions, and the pixel electrode is on the first inner side surface and the common electrode is on the second inner side surface.