OLED Micro Lens Array for Light Extraction and Brightness Uniformity
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Solution Overview
Problem
Organic light emitting diode (OLED) display devices suffer from low light extraction efficiency due to significant light confinement within the device, resulting in uneven brightness across emission areas and reduced luminous efficiency.
Innovation Solution
The OLED display device is designed with a substrate divided into emission and non-emission areas, featuring a micro lens array on the overcoating layer, where first electrode patterns are strategically placed only in specific areas corresponding to the micro lens protrusions and slopes, optimizing the thickness of the organic emission layer to enhance light extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a micro lens array is formed on the overcoating layer to improve light extraction efficiency, then light extraction efficiency is improved, but emission areas show different luminous efficiency causing uneven brightness
Solution Approach 1:
The patent applies local quality by creating different emission layer thicknesses in different regions. The emission layer is thinner in first regions (under micro lens protrusions) and thicker in second regions (between protrusions), allowing each region to be optimized for its specific light extraction characteristics while maintaining overall brightness uniformity
Solution Approach 2:
The emission layer is segmented into regions with different thicknesses corresponding to the micro lens array structure. This segmentation allows independent optimization of light extraction in different areas, resolving the brightness uniformity issue while maintaining improved overall light extraction efficiency
2Loss of energy
If the organic emission layer thickness is reduced to improve light extraction, then light extraction efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
Instead of uniformly reducing the emission layer thickness across the entire device, the patent applies partial action by thinning the layer only in specific first regions under the micro lens protrusions. This selective thinning achieves the light extraction benefit where needed while maintaining adequate thickness in other regions, reducing overall manufacturing precision requirements
Solution Approach 2:
The emission layer is designed with local quality variations, being thinner in first regions for optimal light extraction and thicker in second regions for manufacturing robustness. This localized approach allows each region to have the appropriate thickness for its function without requiring uniform high-precision control across the entire device
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 minimizes brightness differences between emission areas and significantly improves light extraction efficiency, achieving a 14% higher light extraction efficiency compared to comparative examples.
Implementation Method 1
an overcoating layer disposed on the substrate and including a plurality of micro lenses
Implementation Method 2
improve light extraction efficiency
Data Source
AI summary
There is provided an organic light emitting diode display device. The organic light emitting diode display device includes a substrate divided into an emission area and a non-emission area, an overcoating layer disposed on the substrate and including a plurality of micro lenses, a plurality of first electrode patterns disposed on the overcoating layer and spaced away from each other in the emission area, an organic emission layer disposed on the plurality of first electrodes, and a second electrode disposed on the organic emission layer.