Scattering Layer Substrate for OLED Light Extraction
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Solution Overview
Problem
Organic electronic devices face challenges in improving light extraction efficiency and electron transfer efficiency without degrading device performance, particularly due to internal total reflection caused by differences in refractive indices between layers, which affects luminous efficiency and brightness.
Innovation Solution
The implementation of a substrate with a scattering layer and a planarization layer having specific refractive index differences, combined with an electron transfer layer doped with an alkali halide, enhances light extraction and electron transfer efficiency without the need for a separate electron injection layer, thereby improving luminous uniformity and device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional OLED structure is used, then the device can be manufactured with standard processes, but light extraction efficiency is degraded due to internal total reflection caused by refractive index differences between layers
Solution Approach 1:
The patent introduces a scattering layer as an intermediary component between the base material and the organic light-emissive layer. This scattering layer mediates the optical interaction by scattering light that would otherwise undergo internal total reflection at the interface between layers with different refractive indices, thereby improving light extraction efficiency without requiring changes to the standard OLED manufacturing process
Solution Approach 2:
The patent modifies the optical parameters of the device by introducing a scattering layer with specific optical properties. The scattering layer changes the light propagation path and extraction characteristics without altering the fundamental structure or manufacturing process of the OLED, resolving the contradiction between ease of manufacture and light extraction efficiency
2Reliability
If a separate electron injection layer is added to improve electron transfer efficiency, then electron injection performance is enhanced, but device complexity and manufacturing steps increase
Solution Approach 1:
The patent merges the electron transfer function into the existing organic light-emissive layer by doping it with alkali halide. This combines what would traditionally be separate functions (light emission and electron injection/transfer) into a single integrated layer, improving electron transfer efficiency without increasing device complexity or adding separate electron injection layers
Solution Approach 2:
The organic light-emissive layer is designed to perform multiple functions simultaneously: light emission, electron transfer, and charge transport. By making the organic layer universal and multi-functional through alkali halide doping, the patent eliminates the need for dedicated separate layers for each function, thereby improving reliability without increasing device complexity
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 significantly enhances light extraction efficiency and luminous uniformity while simplifying the manufacturing process and eliminating the requirement for a separate electron injection layer, leading to improved device performance and extended lifespan.
Implementation Method 1
a scattering layer which is formed on the base material, includes a binder and scattering particles for scattering light
Implementation Method 2
internal total reflection caused by differences in refractive indices between layers
Implementation Method 3
a planarization layer which is formed on the scattering layer to planarize an uneven surface of the scattering layer, and a refractive index Na of the scattering particles and a refractive index Nb of the planarization layer satisfies the expression |Na-Nb| ≥ 0.3
Implementation Method 4
an electron transfer layer doped with an alkali halide
Data Source
Figure 1~3
Figure 4~5
AI summary
A substrate including a base material; a scattering layer which is formed on the base material, includes a binder and scattering particles for scattering light, and has an uneven structure formed on a surface thereof opposite the base material; and a planarization layer which is formed on the scattering layer and has a flat surface formed thereon, is provided. Here, the refractive index Na of the scattering particles and the refractive index Nb of the planarization layer satisfy the expression |Na-Nb| ≥0.3, an organic electronic device including the substrate, and a method of manufacturing the same are provided. Light-extraction efficiency can be improved and the manufacturing process can be simplified without degrading device performance.