OLED Light Extraction Layer Using Polymer Network Liquid Crystal
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Solution Overview
Problem
Organic light emitting diode (OLED) display panels face challenges in achieving high light transmission efficiency due to internal reflections and light blocking by the black matrix, leading to reduced output and color coordinate variations with viewing angles.
Innovation Solution
Incorporating a light extraction layer with a polymer network liquid crystal (PNLC) and sheared polymer network liquid crystal (S-PNLC) in a convex lens structure, which refracts and scatters side surface light to enhance light transmission and maintain color consistency across viewing angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional OLED display panel structure is used, then the device is simple and easy to manufacture, but light transmission efficiency is reduced due to internal reflections and black matrix blocking
Solution Approach 1:
The light extraction layer is integrated within the display panel structure between the lower and upper substrates, nesting the light management functionality within the existing device architecture rather than adding external components
Solution Approach 2:
The light extraction layer acts as an intermediary component between the organic light emitting layer and the color filter, mediating light propagation by refracting and scattering light to improve extraction efficiency while maintaining color accuracy
2Reliability
If no light extraction layer is used, then the device structure is simpler, but color coordinate variations with viewing angles increase
Solution Approach 1:
The light extraction layer uses regions with different haze values (first region and second region) to locally optimize light extraction in different areas, with the convex lens structure providing localized refraction to control viewing angle characteristics
Solution Approach 2:
The patent utilizes changes in the refractive index and haze parameters of the light extraction layer materials to control light propagation characteristics, maintaining color consistency across different viewing angles through parameter optimization
3Illumination intensity
If internal reflections are not addressed, then the manufacturing process is simpler, but output light is reduced
Solution Approach 1:
The convex lens structure in the light extraction layer uses curved surfaces to refract light at specific angles, directing light that would otherwise be trapped by internal reflection toward the viewer, thereby increasing output light
Solution Approach 2:
The light extraction layer converts potentially harmful internal reflections into beneficial light extraction by refracting the reflected light toward the viewer, transforming a loss mechanism into a gain mechanism for output light
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 light extraction layer increases light transmission efficiency by up to 30% and reduces color coordinate variations by approximately 50% at 70 degrees viewing angle, improving the overall display performance.
Implementation Method 1
a light extraction layer, which includes a first optical layer and a second optical layer, the first light optical layer and the second light optical layer being sequentially arranged in a thickness direction of the display panel, wherein the first light optical layer includes a polymer network liquid crystal and the second light optical layer includes a sheared polymer network liquid crystal having a convex lens structure
Implementation Method 2
refracts and scatters side surface light to enhance light transmission
Implementation Method 3
The light extraction layer changes an optical path of side surface light, which is emitted from the organic light emitting device in an inclined direction along with front surface light
Data Source
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AI summary
An organic light emitting diode display panel (400) including an upper substrate (420), an organic light emitting device (OL) facing the upper substrate and emitting a light to the upper substrate, and a light extraction layer (430, 440, 450, 460) disposed between the upper substrate and the organic light emitting device, including first (431, 441, 451, 461) and second optical layers (432, 442, 452, 462) each having a polymer network liquid crystal and having different optical properties, and exiting the light to the outside of the upper substrate. The optical property of the polymer network liquid crystal in the first optical layer differs from the optical property of the polymer network liquid crystal in the second optical layer.