Chiral Liquid Crystal Layer for OLED Light Extraction
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Solution Overview
Problem
Current organic light-emitting displays (OLEDs) face issues with low screen contrast and outdoor visibility due to reflection from cathode and anode metal layers, and polarizers limit light extraction efficiency, leading to increased power consumption and uneven lifetime of light-emitting devices.
Innovation Solution
A display substrate with a base substrate, light-emitting devices of multiple colors, a chiral liquid crystal layer with a central reflection wavelength matching the emission wavelength of the light-emitting devices, and an anti-reflection layer, such as a circular polarizer or color filter, to enhance light extraction efficiency and balance the lifetime of different colored light-emitting devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If polarizers are used to reduce reflection, then screen contrast and outdoor visibility are improved, but light extraction efficiency decreases and power consumption increases
Solution Approach 1:
The polarizer is divided into multiple sections with different polarization directions, allowing different regions to handle different wavelength ranges. This segmentation enables selective light extraction while reducing overall reflection, thereby improving contrast without excessive power consumption.
Solution Approach 2:
Different regions of the display have locally optimized polarization properties matched to their emission wavelengths. This local quality optimization allows each region to minimize reflection for its specific wavelength range while maintaining high light extraction efficiency, reducing the need for increased power consumption.
2Object-affected harmful factors
If polarizers are used to reduce reflection, then screen contrast and outdoor visibility are improved, but light extraction efficiency decreases
Solution Approach 1:
Different regions of the display have locally optimized polarization properties matched to their emission wavelengths. This local quality optimization allows each region to minimize reflection for its specific wavelength range while maintaining high light extraction efficiency.
Solution Approach 2:
The polarization parameters (direction, wavelength selectivity) are changed across different regions to match the emission characteristics of underlying light-emitting elements. This parameter optimization enables simultaneous achievement of low reflection and high light extraction efficiency.
3Object-affected harmful factors
If conventional polarizers are used, then reflection is reduced, but the lifetime of light-emitting devices becomes uneven across different colors
Solution Approach 1:
The polarizer is segmented into multiple wavelength-selective regions, each optimized for a specific color range. This segmentation allows differential lifetime compensation across colors by adjusting polarization properties to balance the overall display performance.
Solution Approach 2:
Different regions have locally optimized polarization properties that account for the different lifetimes of red, green, and blue light-emitting elements. This local quality adjustment helps balance the effective lifetime and performance across all colors.
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 solution improves light extraction efficiency, reduces power consumption, and balances the lifetime of light-emitting devices, enhancing the overall performance and visibility of OLED displays.
Implementation Method 1
a chiral liquid crystal layer, arranged between the layer where the light-emitting devices are located and the anti-reflection layer; where a central reflection wavelength of the chiral liquid crystal layer is approximately same as an emission wavelength of the at least one color light-emitting device overlapping with the chiral liquid crystal layer
Data Source
AI summary
The present disclosure provides a display substrate and a display device. The display substrate includes a base substrate; light-emitting devices of a plurality of colors arranged in an array on the base substrate; an anti-reflection layer on the side of the layer where the light-emitting device is away from the base substrate; and a chiral liquid crystal layer between the layer where the light-emitting device is and the anti-reflection layer, wherein the orthographic projection of the chiral liquid crystal layer on the base substrate overlaps the orthographic projection of a light-emitting device of at least one color on the base substrate; the central reflection wavelength of the chiral liquid crystal layer is roughly the same as the light-emitting wavelength of the light-emitting device of at least one color overlapping the chiral liquid crystal layer, and the helix direction of the chiral liquid crystal layer is left-handed helix or right-handed helix.