Organic EL Light Guiding Layer with Segmented Dispersion Regions
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Solution Overview
Problem
Organic EL devices experience reduced light output in the front direction due to total reflection at the interface between the light-transmissive electrode and substrate, despite the use of a light dispersion layer to enhance light output in diagonal directions.
Innovation Solution
A light guiding layer with a coplanar arrangement of light dispersion and transmissive regions, where the light dispersion region contains light dispersion particles and a binder resin, and the transmissive region has a lower particle ratio, is introduced to scatter light in diagonal directions while allowing unscattered light to pass through in the front direction, improving overall light output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the light dispersion layer contains a high concentration of light dispersion particles, then light scattering in diagonal directions is enhanced, but the uniformity of the light-transmissive electrode thickness is compromised
Solution Approach 1:
The light dispersion particles are distributed non-uniformly within the light dispersion layer, with higher concentration in the first region and lower concentration in the second region. This local quality variation allows sufficient light scattering in regions where it is needed while maintaining electrode thickness uniformity in regions where the electrode is formed.
Solution Approach 2:
The light dispersion layer is segmented into regions with different particle concentrations, allowing the electrode formation process to occur in regions with lower particle density (second region) where uniform thickness is critical, while light scattering functions are fulfilled in regions with higher particle density (first region).
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 effectively suppresses the reduction of light output in the front direction while increasing light output in diagonal directions, enhancing the overall light output of the organic EL device without causing short-circuits.
Implementation Method 1
The light dispersion layer 5 has a bumpy surface, not allowing the thin light-transmissive electrode 3 to be formed with a uniform thickness... The light dispersion layer 5 of the light guiding layer 4 in this arrangement disperses the light emitted from the light emitting layer 2 toward other directions for improving light output by suppressing the total reflection of light
Data Source
AI summary
An organic EL device in the present invention comprises a light-transmissive substrate 1, an organic light emitting layer 2, a light-transmissive electrode 3 disposed between the light-transmissive substrate 1 and the organic light emitting layer 2, and a light guiding layer 4 which is disposed between the substrate 1 and the light-transmissive electrode 3. The light guiding layer 4 is configured to alter light direction. The organic EL device is configured to emit light from the organic light emitting layer 2, and allow the light to propagate out through said light guiding layer 4, the light-transmissive electrode 3, and the light-transmissive substrate 1. The light guiding layer 4 includes a light dispersion layer 5. The light dispersion layer 5 is formed with a light dispersion region 8 and a light-transmissive region 9, which are arranged in a coplanar relation within said light dispersion layer 5. The light dispersion region 8 contains light dispersion particles 6 and a binder resin 7. The light-transmissive region 9 contains the light dispersion particles 6 at a lower ratio than the light dispersion region 8. The organic EL device in the present invention enables to improve an overall light output by suppressing the reduction of light output in the front direction as well as increasing light output in diagonal directions.