OLED Light Extraction Layer with Graded Refractive Index
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Solution Overview
Problem
In OLED display technology, a significant portion of large-angle light emitted by light-emitting elements is trapped inside the display panel, reducing light-extraction efficiency and affecting the overall brightness and flexibility of the display.
Innovation Solution
A display panel design incorporating a light extraction layer with refractive index units of different indices, where the first refractive index unit overlaps the light-emitting elements and has a central portion and a functional portion with gradually changing thickness, deflects large-angle light towards the front viewing direction through a functional interface with the second refractive index unit, enhancing light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional OLED display panel structure is used, then the device achieves thinness and flexibility, but a significant portion of large-angle light is trapped inside the panel, reducing light extraction efficiency
Solution Approach 1:
The light extraction layer is segmented into multiple refractive index units with different refractive indices arranged in specific patterns. This segmentation creates multiple optical interfaces that work together to extract light at different angles, thereby improving overall light extraction efficiency without requiring a complete structural overhaul
Solution Approach 2:
Different regions of the display panel are assigned different local optical properties through the use of refractive index units with varying refractive indices. The first refractive index units are positioned to extract light from specific angular ranges, while the second refractive index units handle other angular ranges, creating locally optimized light extraction throughout the panel
2Productivity
If the light extraction layer uses multiple refractive index units with different indices, then light extraction efficiency is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent varies the refractive index parameter across different units within the light extraction layer. By carefully selecting and arranging units with different refractive indices, the system optimizes light extraction efficiency for various viewing angles while maintaining a manufacturing process that builds upon conventional OLED structures
Solution Approach 2:
The light extraction layer functions as a composite structure combining multiple materials with different refractive indices. This composite approach allows the system to leverage the optical properties of different materials to extract light more effectively while potentially using established material deposition techniques
3Illumination intensity
If large-angle light is redirected towards the front viewing direction, then brightness is enhanced, but the angular distribution of emitted light is altered
Solution Approach 1:
The patent addresses the angular distribution issue by introducing a spatial dimension to light extraction. Instead of attempting to control all light at a single interface, the segmented refractive index units are distributed across different positions and orientations, extracting light from various angular dimensions and redirecting them toward the front viewing direction through multiple incremental adjustments
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 significantly increases the probability of light emission from the display panel, improving light extraction efficiency and enhancing the display's brightness and flexibility by effectively redirecting trapped light towards the viewer.
Implementation Method 1
The light extraction layer includes at least one first refractive index unit and a second refractive index unit, and a refractive index of each of the at least one first refractive index unit is different from a refractive index of the second refractive index unit
Data Source
AI summary
A display panel and a display apparatus are provided. The display panel includes a substrate, a light-emitting element layer located on a side of the substrate and including light-emitting elements, and a light extraction layer located on a side of the light-emitting element layer away from the substrate. The light extraction layer includes a first refractive index unit and a second refractive index unit that have different refractive indices. In a direction perpendicular to a plane of the substrate, one first refractive index unit overlaps one light-emitting element. The first refractive index unit includes a central portion and a functional portion surrounding the central portion, and a thickness of the functional portion changes gradually in a direction from the central portion to the functional portion. The second refractive index unit is located on a side of the first refractive index unit away from the substrate, and covers the functional portion.