Organic EL Display Panel Segmented Light Emission
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Solution Overview
Problem
There is a demand for improving the luminance of organic EL display panels, as existing technologies do not effectively maximize light emission from the organic light-emitting layers.
Innovation Solution
An organic EL display panel design that includes a substrate with pixel electrodes, an insulating film recessed to cover adjacent pixel electrode edges, banks elongated in the column direction, a hole transport layer between the banks, and an organic light-emitting layer over the hole transport layer, allowing light emission from both conventional and new light-emitting portions above the pixel electrodes and insulating films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional line-bank method is used to form banks in parallel lines, then organic light-emitting layers are partitioned into stripes, but light emission is limited to specific regions only, resulting in insufficient luminance
Solution Approach 1:
The patent divides the light-emitting region into multiple segments: first light-emitting portions above pixel electrodes excluding insulating film regions, and second light-emitting portions above both pixel electrodes and insulating films. This segmentation allows different regions to contribute to light emission, increasing the total light-emitting surface area and improving luminance.
Solution Approach 2:
The patent extends light emission from the traditional one-dimensional stripe pattern (first light-emitting portions) to include two-dimensional areas above the insulating films (second light-emitting portions). This dimensional expansion utilizes previously non-contributing regions, thereby increasing the overall light-emitting surface area and luminance.
2Illumination intensity
If pixel-defining layers are disposed to coat edges of pixel electrodes, then adjacent pixels are separated, but regions above the pixel-defining layers do not contribute to light emission, limiting luminance improvement
Solution Approach 1:
The insulating film serves multiple functions: it acts as a pixel-defining layer to separate adjacent pixels and prevent ink mixing, while simultaneously allowing light emission from regions above it (second light-emitting portions). This multi-functionality eliminates the need for additional structures and increases light-emitting surface area without increasing device complexity.
Solution Approach 2:
The insulating film structure automatically creates both pixel separation and light-emitting regions. By forming the insulating film to coat edges of pixel electrodes and having recessed portions, the structure self-generates the dual functionality of pixel definition and light emission enhancement without requiring separate components or complex additional structures.
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 design increases the light-emitting surface area, resulting in enhanced luminance intensity by enabling light emission from previously non-contributing portions, thereby improving the overall brightness of the organic EL display panel.
Implementation Method 1
organic EL elements, which are light-emitting elements that use electroluminescence of a solid fluorescent material
Data Source
AI summary
An organic EL display panel offering improved luminance includes: a substrate; pixel electrodes arranged in rows and columns; an insulating film coating the confronting edges of pixel electrodes adjacent in a column direction; banks each elongated in the column direction over a gap between pixel electrodes adjacent in the row direction; a hole transport layer in a gap between the banks; an organic light-emitting layer over the hole transport layer; and a common electrode over the organic light-emitting layer. Light is emitted from a first light-emitting portion and second light-emitting portions of the light-emitting layer. The first light-emitting portion is a portion above the pixel electrodes excluding where the insulating film is disposed. The second light-emitting portions are portions above both the pixel electrodes and the insulating film.