OLED Passivation Layer Refractive Index for Light Concentration
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Solution Overview
Problem
OLED displays face reduced light-emission efficiency due to fillers absorbing part of the emitted light, which also fail to prevent color mixture between pixels effectively.
Innovation Solution
A filler structure with a first passivation layer having a higher refractive index than a second passivation layer is used, where the first passivation layer overlaps the organic light-emitting layer, and the second passivation layer does not, to concentrate light and minimize diffusion, enhancing light-emission efficiency and preventing color mixture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If filler is used between substrates, then structural support and sealing are provided, but light-emission efficiency is reduced due to light absorption
Solution Approach 1:
The patent changes the refractive index parameter of the passivation layer material to reduce light absorption. By selecting a material with refractive index between 1.5-2.0 (preferably 1.6-1.8) for the first passivation layer, light transmission is optimized while maintaining structural support function.
Solution Approach 2:
The patent applies different refractive index properties to different regions: the first passivation layer (overlapping emission regions) has higher refractive index (1.5-2.0) to concentrate light, while the second passivation layer (non-overlapping regions) has lower refractive index (1.3-1.5) to minimize interference. This local differentiation resolves the contradiction between structural support and light emission efficiency.
2Ease of manufacture
If uniform passivation layer is used, then manufacturing is simplified, but color mixture between pixels cannot be prevented effectively
Solution Approach 1:
The patent divides the passivation layer into two regions with different refractive indices: first passivation layer (n=1.5-2.0) over emission regions and second passivation layer (n=1.3-1.5) in non-emission regions. This local quality differentiation prevents color mixture while maintaining reasonable manufacturing complexity through a single-layer formation process.
Solution Approach 2:
The passivation layer is segmented into functionally distinct first and second regions based on their spatial relationship with emission regions. This segmentation enables precise control of light propagation paths to prevent color mixture between adjacent pixels while maintaining ease of manufacture through integrated layer formation.
3Illumination intensity
If high refractive index material is used throughout, then light concentration is improved, but light diffusion to adjacent pixels increases causing color mixture
Solution Approach 1:
The patent strategically places high refractive index material (first passivation layer, n=1.5-2.0) only in regions overlapping emission areas to concentrate light vertically, while using low refractive index material (second passivation layer, n=1.3-1.5) in non-overlapping regions to prevent lateral light diffusion. This spatially differentiated approach simultaneously achieves light concentration and color separation.
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 improves light-emission efficiency by concentrating light in the high refractive index passivation layer and minimizing light sent to the low refractive index layer, thereby enhancing the display's brightness and preventing color mixture between pixels.
Implementation Method 1
a refractive index of the first passivation layer is higher than a refractive index of the second passivation layer
Implementation Method 2
a refractive index of the first passivation layer is higher than a refractive index of the second passivation layer
Data Source
AI summary
An organic light-emitting diode (OLED) display and method of manufacturing the same are disclosed. In one aspect, the OLED display includes a substrate which includes non-emission regions and emission regions, a first electrode which is formed on each of the emission regions of the substrate, an organic light-emitting layer which is formed on the first electrode, a second electrode which is formed on the organic light-emitting layer and the substrate and a passivation layer which is formed on the second electrode. The passivation layer includes a first passivation layer which substantially overlaps the organic light-emitting layer and a second passivation layer which does not overlap the organic light-emitting layer, wherein the refractive index of the first passivation layer is higher than the refractive index of the second passivation layer.