Organic EL Buffer Layer for Natural Off-State Appearance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional organic EL display devices have a non-light-emitting region that is shielded, causing the shape of the light-emitting region to be visible even when light is not being emitted, resulting in an unnatural appearance.
Innovation Solution
An organic EL element with a light-transmissive substrate, a pair of electrode layers where at least one is light-transmissive, and a planar light-emitting layer, along with a buffer layer in a non-light-emitting region to reduce optical differences between light-emitting and non-light-emitting regions, allowing for a natural light-emitting surface display even when not emitting light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a light-shielding layer is disposed in the non-light-emitting region to shield the pattern, then the contrast of the pattern layer is improved, but the shape of the light-emitting region becomes visible when light is not being emitted, resulting in an unnatural appearance
Solution Approach 1:
A buffer layer is introduced as an intermediary element between the light-emitting region and the light-shielding layer. This buffer layer has optical properties that are intermediate between the light-emitting region and the shielding layer, reducing the abrupt optical transition and making the light-emitting region shape less visible when the device is off, while still allowing the light-shielding layer to maintain pattern contrast when on.
Solution Approach 2:
The optical parameters (such as refractive index, absorption coefficient, or thickness) of the buffer layer are specifically designed to reduce the optical contrast between the light-emitting region and the non-light-emitting region when the device is off. This parameter optimization allows the light-emitting region shape to be less conspicuous in the off state while maintaining pattern visibility in the on state.
2Manufacturing precision
If the non-light-emitting region is shielded with a light-shielding layer, then the light-emitting pattern contrast is improved, but the light-emitting surface appears unnatural when light is not being emitted
Solution Approach 1:
The buffer layer serves as an optical intermediary that smooths the transition between the light-emitting and non-light-emitting regions. It reduces the abrupt optical discontinuity caused by the light-shielding layer, creating a more uniform light-emitting surface appearance when the device is off, while preserving the pattern contrast when the device is on.
Solution Approach 2:
The buffer layer is selectively positioned in specific regions (such as the non-light-emitting region adjacent to the light-emitting region) to provide localized optical modification. This local application allows the buffer layer to address the uniformity issue in specific areas without affecting the overall pattern contrast or requiring modification of the entire device structure.
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 solution enables a natural light-emitting surface to be displayed when light is not being emitted, reducing the visibility of the light-emitting region's shape and maintaining a natural appearance.
Implementation Method 1
The buffer layer is for reducing a difference in an optical characteristic between the first region and the second region with respect to a predetermined light
Data Source
AI summary
An organic EL element includes: a substrate that is light-transmissive; a pair of electrode layers (first electrode layer and second electrode layer) disposed above the substrate, at least one of the pair of electrode layers being light-transmissive; and a planar light-emitting layer disposed between the first electrode layer and second electrode layer. The first electrode layer is disposed in a first region in a plan view. The organic EL element further includes a buffer layer disposed, in a plan view, in a second region adjacent the first region. The buffer layer is for reducing a difference in an optical characteristic between the first region and the second region with respect to a predetermined light.