OLED Capping Layer Refractive Index Gradient for Light Extraction
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Solution Overview
Problem
Current OLED display apparatuses face challenges in achieving high light extraction efficiency and minimizing color-shift when viewed from different angles due to limitations in the design of the capping layer, which affects the refractive indices and material combinations used.
Innovation Solution
The implementation of a capping layer comprising a first and second material with different refractive indices, where the second capping layer includes specific organic low molecular weight compounds and organic polymer compounds, is used to enhance light extraction efficiency and reduce color-shift by amplifying light through constructive interference and resonance effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional single-layer capping layer is used, then the device structure is simple, but light extraction efficiency is low and color-shift occurs when viewed from different angles
Solution Approach 1:
The capping layer is divided into multiple sub-layers (first capping layer, second capping layer, and third capping layer) with different materials and refractive indices. This segmentation allows each layer to contribute differently to light extraction, improving overall efficiency while managing the complexity through systematic design.
Solution Approach 2:
The patent employs composite material structures where each capping layer contains specific organic compounds with different refractive indices. The first capping layer uses compounds with refractive index 1.7-2.0, the second layer uses compounds with refractive index 1.4-1.6, and the third layer uses compounds with refractive index 1.3-1.5, creating a gradient composite structure that optimizes light extraction.
2Reliability
If a conventional capping layer design is used, then manufacturing is simpler, but color-shift occurs when viewed from different angles
Solution Approach 1:
Different regions of the capping layer structure are assigned different material properties. Each capping layer is positioned at specific locations above the OLED device with tailored refractive indices, creating local quality variations that collectively eliminate color-shift across different viewing angles while maintaining manufacturing feasibility.
3Illumination intensity
If the capping layer uses materials with different refractive indices, then light extraction efficiency is improved, but the material selection and deposition process becomes more complex
Solution Approach 1:
The patent systematically varies the refractive index parameter across different capping layers, creating a gradient from 1.7-2.0 in the first layer to 1.4-1.6 in the second layer, and 1.3-1.5 in the third layer. This parameter change strategy optimizes light extraction efficiency while providing clear guidance for material selection and deposition processes.
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 significantly improves light extraction efficiency and reduces color-shift when viewed from various angles, resulting in a more effective OLED display apparatus with enhanced performance.
Implementation Method 1
amplifying light through constructive interference and resonance effects
Implementation Method 2
amplifying light through constructive interference and resonance effects
Implementation Method 3
The second capping layer includes a first material and a second material that are different from each other
Data Source
AI summary
Provided are an organic light-emitting diode display apparatus and a method of manufacturing the same. In an exemplary embodiment, an organic light-emitting diode (OLED) display apparatus includes a substrate, an OLED device on the substrate, and a capping layer on the organic light-emitting device. The capping layer includes a first capping layer and a second capping layer. The second capping layer includes a first material and a second material. The first material and the second material are different from each other.