Organic EL Light Shielding Layer for Resolution Control
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Solution Overview
Problem
In organic EL devices, the isotropic flow of current through conductive polymers leads to light emission beyond the regulated area between electrodes, resulting in reduced image resolution and display quality in image forming apparatuses.
Innovation Solution
A top emission-type organic EL device structure is implemented, featuring a light shielding layer or auxiliary electrode that covers the peripheral edge of the second electrode, with an opening part matching the electrode shape, to control and focus light emission, reducing the light emitting area and preventing light spread.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conductive polymer is used as a hole injecting layer, then current flows isotropically through the layer, but the light emitting area becomes larger than the area regulated by the two electrodes, causing light spread and reduced image resolution
Solution Approach 1:
The patent introduces a light shielding layer that segments the light emission area by covering the peripheral edge portions of the second electrode. This segmentation prevents light from spreading beyond the intended emission area, thereby resolving the contradiction between ease of manufacture (using conductive polymer) and manufacturing precision (controlling light emitting area).
Solution Approach 2:
The light shielding layer acts as an intermediary element between the organic function layer and the external environment. It mediates the light emission by allowing light to pass through the central opening while blocking light from the peripheral edge portions, thus controlling the light emitting area without modifying the conductive polymer layer itself.
2Manufacturing precision
If the light emitting area is reduced to improve resolution, then image resolution improves, but light intensity uniformity and light emitting capability may deteriorate
Solution Approach 1:
The light shielding layer implements local quality by selectively covering only the peripheral edge portions of the second electrode while leaving the central region open. This localized approach reduces the light emitting area to improve resolution without affecting the light intensity uniformity in the central emission area, thus resolving the contradiction between precision and illumination quality.
Solution Approach 2:
The light shielding layer creates an asymmetric structure where the peripheral edge portions are covered while the central area remains open for light emission. This asymmetric design allows the system to achieve both reduced light emitting area (improved resolution) and maintained light intensity uniformity in the emission region.
3Manufacturing precision
If a light shielding layer covers the peripheral edge of the second electrode, then light spread is suppressed and resolution improves, but device complexity increases
Solution Approach 1:
The light shielding layer serves multiple functions: it acts as a light shield to prevent light spread, provides structural support, and defines the emission area boundary. By combining multiple functions into a single component, the patent reduces the overall device complexity while achieving improved light emitting area control.
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 light emitting capability with reduced blur and uniformity, achieving higher resolution and improved display quality by minimizing light loss and maintaining consistent intensity.
Implementation Method 1
a light shielding layer covering a part of the second electrode is formed on the second electrode
Implementation Method 2
When an electric potential difference is generated between the pixel electrode and the common electrode, holes injected from the pixel electrode and electrons injected from the common electrode are combined on the organic function layer so as to emit light
Data Source
AI summary
A top emission-type organic EL device includes a first electrode formed on a substrate, an organic function layer formed on the first electrode, and a second electrode formed on the organic function layer, wherein light generated from the organic function layer is extracted from the second electrode side, and wherein a light shielding layer covering a part of the second electrode is formed on the second electrode.