Organic EL Device Recessed Substrate Light Extraction
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Solution Overview
Problem
Existing organic electroluminescence (EL) devices have low light extraction efficiency due to most light components propagating in the lateral direction being trapped within the film and not extracted to the display surface, resulting in insufficient luminous current efficiency.
Innovation Solution
The organic electroluminescence device incorporates a substrate with recessed portions, a reflective layer, a filling layer, a transparent first electrode, an organic light emitting layer, and a transparent second electrode, where the first electrode's end portion is positioned inside the recessed portion and at a distance from the reflective layer, enhancing light extraction by altering the optical path and utilizing a microcavity structure to intensify specific wavelengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a reflective layer is provided on a substrate surface to extract light, then light extraction efficiency is improved, but most light components propagating in the lateral direction are still trapped within the film and cannot be extracted
Solution Approach 1:
The substrate surface is modified with recessed portions that have curved or inclined inner surfaces. This curvature enables light components propagating in lateral directions to be reflected toward the display surface, overcoming the limitation of flat reflective surfaces that only extract vertically emitted light. The curved geometry creates multiple reflection paths for trapped light components.
Solution Approach 2:
The invention introduces a vertical dimension to light extraction by creating recessed portions that extend downward from the substrate surface. This three-dimensional structure allows light to be extracted not only from the top surface but also from the inner surfaces of the recesses, adding extraction pathways in multiple spatial dimensions and enabling lateral light components to reach the display surface.
2Loss of energy
If the first electrode is positioned close to the reflective layer to maximize light interaction, then light extraction is enhanced, but light components scatter within the film and cannot be extracted to the display surface
Solution Approach 1:
The recessed portions are strategically positioned and sized to create localized optical cavities where light can be effectively trapped and redirected. The local geometry of each recessed portion is optimized to match the wavelength and emission characteristics of the organic light emitting layer, creating resonant conditions that enhance light extraction efficiency for specific light components while maintaining overall device performance.
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 significantly improves light extraction efficiency, increasing luminous current efficiency and enabling displays with lower power consumption by effectively redirecting and extracting previously trapped light components.
Implementation Method 1
a reflective layer configured to reflect light discharged to a support substrate side
Implementation Method 2
each recessed portion includes an inclined face along an outer edge of an organic light emitting layer of the corresponding display element
Implementation Method 3
An organic EL element is a light emitting element, luminescent components of which emit light evenly in all directions
Data Source
AI summary
An organic electroluminescence device according to an aspect of the disclosure includes a base material including one face provided with a recessed portion; and a light emitting element including a reflective layer provided on at least a surface of the recessed portion, a filling layer having optical transparency and filling the inside of the recessed portion with the reflective layer interposed between the filling layer and the recessed portion, a first electrode having optical transparency and provided on at least an upper-layer side of the filling layer, an organic layer containing at least a light emitting layer and provided on an upper layer of the first electrode, a second electrode having optical transparency and provided on an upper-layer side of the organic layer, and an edge cover layer covering at least an end portion of the first electrode, and in the organic electroluminescence device, an upper face of the first electrode at a position of the recessed portion is positioned below a plane including an upper face of the reflective layer, and the end portion of the first electrode is located inside the recessed portion and at a distance from the reflective layer.