Hybrid Alignment Liquid Crystal Layer for OLED Color Purity
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Solution Overview
Problem
Organic light-emitting display devices face issues with color mixing due to light leakage between sub-pixel areas and external light reflection, particularly as they increase in size or resolution, affecting color purity and gamut.
Innovation Solution
The implementation of a liquid crystal layer with hybrid alignment in light-emitting areas and tilted alignment in non-light-emitting areas, where liquid crystal molecules change from horizontal to vertical alignment in light-emitting areas and remain tilted in non-light-emitting areas, combined with a polarization layer to prevent color mixing and external light reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a liquid crystal layer with hybrid alignment is used in light-emitting areas, then color mixing between sub-pixel areas is prevented and color purity is improved, but device complexity increases due to the need for different alignment configurations in different areas
Solution Approach 1:
The patent applies different liquid crystal alignment configurations to different spatial locations: hybrid alignment (horizontal to vertical transition) is used in light-emitting areas to prevent color mixing, while tilted alignment is used in non-light-emitting areas. This local differentiation of quality resolves the contradiction by optimizing each region's alignment according to its specific functional requirements.
2Manufacturing precision
If a polarization layer is added to prevent external light reflection, then color gamut is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The liquid crystal layer is designed to perform multiple functions simultaneously: it controls light transmission for display, prevents color mixing through hybrid alignment in light-emitting areas, and reduces external light reflection through tilted alignment in non-light-emitting areas. By making the liquid crystal layer multi-functional, the patent avoids adding separate dedicated components for each function, thus improving color gamut while limiting the increase in device complexity.
3Ease of manufacture
If white organic light-emitting layer is formed equally in all sub-pixels with color filters, then manufacturing is simplified, but light leakage defects cause color mixing between adjacent sub-pixel areas
Solution Approach 1:
The patent changes the optical parameter of the liquid crystal layer by implementing hybrid alignment in light-emitting areas, where the alignment transitions from horizontal to vertical. This parameter change enables the liquid crystal to selectively control light transmission and prevent color mixing between adjacent sub-pixels, while the underlying white organic light-emitting layer structure remains simple and easy to manufacture.
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 enhances color purity and gamut by preventing color mixing between sub-pixel areas and reduces external light reflection, improving the overall performance of the organic light-emitting display device.
Implementation Method 1
liquid crystal molecules of the liquid crystal layer disposed in the light-emitting areas are in a hybrid alignment. In the hybrid alignment, an alignment of the liquid crystal molecules gradually changes from a horizontal alignment to a vertical alignment
Implementation Method 2
liquid crystal molecules of the liquid crystal layer disposed in the non-light-emitting areas are in a tilted alignment
Implementation Method 3
a polarization layer disposed on the second substrate, and the polarization layer transmits light linearly polarized in a first direction
Data Source
AI summary
An organic light-emitting display device includes a first substrate having sub-pixel areas, each sub-pixel area having a light-emitting area and a non-light-emitting area; thin-film transistors respectively in non-light-emitting areas of the sub-pixel areas; a first planarization layer in the sub-pixel areas while covering the thin-film transistors; organic light-emitting elements on the first planarization layer and in light-emitting areas of the sub-pixel areas; a liquid crystal layer on the organic light-emitting elements and in the sub-pixel areas and in an area between the sub-pixel areas; and a second substrate on the liquid crystal layer. Liquid crystal molecules of the liquid crystal layer in the light-emitting areas are in a hybrid alignment. In the hybrid alignment, an alignment of the liquid crystal molecules gradually changes from a horizontal alignment to a vertical alignment. Liquid crystal molecules of the liquid crystal layer in the non-light-emitting areas are in a tilted alignment.