OLED Homogeneous Brightness via Suppressed Injection Zones
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Solution Overview
Problem
Organic light-emitting devices (OLEDs) face challenges in achieving homogeneous luminance distribution, leading to uneven brightness across the active layer, which is crucial for large-area light sources requiring uniform illumination.
Innovation Solution
The design incorporates a first contact strip for injecting charge carriers along one side surface and a second contact strip along the adjacent side surface, with specific return areas where charge carrier injection is suppressed, limiting recombination and maintaining consistent luminance across the device, achieved through strategic conductivity profiles and geometric configurations of the contact strips.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If charge carrier injection is enhanced at corner edges to improve overall device performance, then the luminance in those areas becomes excessively high, but this creates non-uniform luminance distribution across the active layer
Solution Approach 1:
The patent applies local quality by creating return areas with different electrical properties than the rest of the contact strips. These return areas have suppressed charge carrier injection capability, making them electrically distinct from the main contact strip regions. This local differentiation allows corner edge areas to have reduced charge carrier injection, compensating for the excessive luminance that would otherwise occur and achieving more uniform overall luminance distribution across the active layer.
2Quantity of substance
If contact strips are extended to cover the entire side surface for maximum charge carrier injection, then charge carrier density increases, but this leads to non-linear current increase and excessive luminance in certain areas
Solution Approach 1:
The patent segments the contact strip into functionally distinct regions: main contact strip areas that provide charge carrier injection, and return areas where injection is suppressed. This segmentation allows different portions of the same contact structure to serve different purposes - some regions inject charge carriers while others limit injection, thereby controlling the overall charge carrier density and preventing excessive luminance in specific areas.
Solution Approach 2:
By creating return areas with suppressed charge carrier injection, the patent applies local quality to differentiate electrical properties within the contact strip structure. This allows specific locations (return areas) to have reduced charge carrier injection capability compared to the main contact strip regions, enabling precise control over charge carrier density distribution and luminance uniformity across the active layer.
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 approach results in a significantly more homogeneous luminance distribution, making the OLED suitable for large-area, flat light sources with consistent illumination, even in areas where charge carrier densities are high.
Implementation Method 1
The injected holes and electrons each migrate (under the influence of an externally applied electric field) to the oppositely charged electrode and, upon recombination in the active layer, produce electroluminescent emission.
Implementation Method 2
A first contact strip for injecting charge carriers of a first type into the active layer extends along the first side surface. A second contact strip for injecting charge carriers of a second type into the active layer extends along the second side surface.
Data Source
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AI summary
The invention relates to an organic light-emitting device (100) having an active layer (106) for producing radiation with a first side surface (400) and a second side surface, the first side surface and the second side surface meeting each other at a corner edge (404). Said device further comprises a first contact connection, which extends along the first side surface (400), for the injection of charge carriers of a first type into the active layer (106), and a second contact connection, which extends along the second side surface, for the injection of charge carriers of a second type into the active layer (106). The first side surface (400) has a cancellation region (700) adjacent to the corner edge (404), and the injection of charge carriers from the first contact connection is completely suppressed in the cancellation region (700).