Nano-structured Reflective Layer for OLED Micro-cavity Resolution
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Solution Overview
Problem
Conventional organic light-emitting devices (OLEDs) face challenges in achieving high color purity and ultra-high resolution without the use of a color filter, particularly in sub-micron sized pixels where efficiency and color reproduction are compromised due to reduced resonance areas and increased edge proportions.
Innovation Solution
The implementation of a light-emitting device with a reflective layer featuring nano-structures arranged in a regular periodic structure, where the spacing between nano-structures is less than 70 nm, forming a micro-cavity that resonates at specific wavelengths, allowing for high-resolution displays without the need for a color filter, by optimizing the width, height, and periodicity of the nano-structures to match emission wavelengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the pixel size is reduced to sub-micron dimensions to achieve ultra-high resolution, then the resolution is improved, but the resonance area is reduced and edge proportion increases, causing luminous efficiency to deteriorate
Solution Approach 1:
The patent applies local quality by creating different nano-structure configurations in different regions of the reflective layer. The central portion has a first interval between adjacent nano-structures, while the peripheral portion has a second interval, allowing each region to be optimized for its specific function - the center for resonance and the periphery for light extraction, thereby maintaining efficiency in sub-micron pixels
Solution Approach 2:
The patent transitions from considering only the two-dimensional pixel layout to incorporating the vertical dimension by designing the reflective layer with depth-varying nano-structures. The nano-structures have different intervals at different depths (central vs peripheral portions), adding a spatial dimension to the design that enables simultaneous optimization of resonance and light extraction in sub-micron dimensions
2Loss of energy
If the interval between nano-structures is reduced to increase resonance area, then luminous efficiency is improved, but the spacing between subpixels may be insufficient, reducing manufacturing precision
Solution Approach 1:
The patent segments the reflective layer into distinct central and peripheral regions with different nano-structure intervals. This segmentation allows the central portion to have larger intervals for resonance while the peripheral portion has smaller intervals for precise subpixel definition, resolving the conflict between luminous efficiency and manufacturing precision
Solution Approach 2:
Different intervals are assigned to different locations within the reflective layer - the central portion uses a first interval optimized for resonance, while the peripheral portion uses a second interval optimized for subpixel separation. This local optimization enables both high luminous efficiency and precise manufacturing
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 approach enables high color purity and improved luminous efficiency in sub-micron sized OLEDs, achieving ultra-high resolution displays with reduced luminous efficiency loss and enhanced color reproduction, even at smaller pixel sizes.
Implementation Method 1
the reflective layer and the second electrode form a micro-cavity having a resonance wavelength
Implementation Method 2
as a resonance mainly occurs in the meta-structure
Data Source
Figure 1
Figure 2~3
Figure 4A~4B
AI summary
Provided are a light-emitting device and a display apparatus. The light-emitting device includes: a reflective layer including a plurality of nano-structures that are two-dimensionally arranged in a regular periodic structure; a first electrode disposed on the plurality of nano-structures of the reflective layer; an organic emission layer disposed on the first electrode; and a second electrode disposed on the organic emission layer. An interval between adjacent nano-structures in a central portion of the reflective layer or an interval between adjacent nano-structures in a peripheral portion surrounding the central portion of the reflective layer is equal to or less than 70 nm.