OLED Light Extraction via Shielding Distance Optimization
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Solution Overview
Problem
In typical organic light-emitting display apparatuses, a significant proportion of light emitted from the emission layer is not externally emitted due to refraction at interfaces, leading to reduced brightness and increased power consumption.
Innovation Solution
The organic light-emitting display apparatus includes a pixel electrode, a light emission layer, a plurality of upper layers, a light-shielding layer that does not overlap the emission layer, and a color filter layer, where the distance between the emission area and the light-shielding layer is optimized to satisfy a specific inequality involving refraction indices and thicknesses to enhance light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If light is emitted from the emission layer in a typical organic light-emitting display apparatus, then light is generated, but a large proportion of light is not externally emitted due to refraction at interfaces, leading to brightness reduction
Solution Approach 1:
The patent optimizes the distance L between the emission area and light-shielding layer by changing geometric parameters to satisfy a specific inequality relationship involving refraction indices and thicknesses of multiple layers. This parameter optimization enables light to be extracted at angles that avoid total internal reflection, thereby improving light extraction efficiency and brightness without increasing power consumption.
Solution Approach 2:
The patent introduces a light-shielding layer positioned at a specific distance from the emission layer, creating a three-dimensional spatial arrangement that controls light propagation paths. By positioning the light-shielding layer to not overlap the emission layer and maintaining distance L that satisfies the inequality, the patent guides light extraction in specific angular directions, effectively using spatial dimensionality to overcome the two-dimensional interface refraction problem.
2Illumination intensity
If power consumption is increased to compensate for brightness reduction, then brightness can be maintained, but energy efficiency deteriorates
Solution Approach 1:
The patent changes the geometric parameter L (distance between emission area and light-shielding layer) to satisfy a specific inequality relationship. This parameter optimization improves light extraction efficiency, allowing the display to achieve desired brightness levels without increasing power consumption, thus resolving the trade-off between brightness and energy efficiency.
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 increases the extraction efficiency of light emitted from the emission layer, reducing the need for increased power consumption to achieve desired brightness levels.
Implementation Method 1
As the light emitted from the light emission layer passes through various layers, refraction of light may occur at interfaces and an optical path is determined accordingly.
Data Source
AI summary
An organic light-emitting display apparatus includes a pixel electrode, a light emission layer over the pixel electrode, an opposite electrode covering the light emission layer, a plurality of upper layers over the opposite electrode, a light-shielding layer over the upper layers. A distance L between an edge of an emission area of the light emission layer and an edge of the light-shielding layer when viewed in a thickness direction satisfies Inequality below:L≥∑i=1mditan(sin-1(nairnisinθair))+dBMtan(sin-1(nairnCFsinθair))[Inequality]wherein m represents the number of the upper layers, ni and di represent a refraction index and a thickness of each of the upper layers, respectively, dBM represents a thickness of the light-shielding layer, nCF represents a refraction index of the color filter layer, nair represents a refraction index of air, and θair represents a refraction angle in external air after light generated from the light emission layer passes through the color filter layer.