OLED Overcoat Layer Micro Lens Array Light Extraction
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Solution Overview
Problem
Organic light emitting devices face inefficiencies in light extraction due to light being trapped within the device, leading to reduced outward light emitting efficiency and increased power consumption.
Innovation Solution
Incorporating a convex or concave overcoat layer with specific morphological features on the substrate, including convex or concave parts with controlled Full Width at Half Maximum (FWHM) and aspect ratios, to alter the light path and enhance light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a Micro Lens Array (MLA) is attached to the outside of a substrate to improve light extraction efficiency, then outward light emitting efficiency is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent integrates the micro lens array structure directly into the overcoat layer that is already part of the OLED stack, rather than attaching it as a separate external component. This merging of functions reduces device complexity while maintaining the light extraction enhancement benefit
Solution Approach 2:
The overcoat layer is designed to serve multiple functions: it provides the micro lens array structure for light extraction enhancement, maintains electrical insulation, and serves as a protective layer. This multi-functionality eliminates the need for separate MLA attachment while achieving the same light extraction improvement
2Productivity
If a Micro Lens Array (MLA) is attached to improve light extraction efficiency, then light emission quantity increases, but manufacturing precision requirements increase
Solution Approach 1:
The micro lens array is formed as an integral part of the overcoat layer deposition process, allowing the lens structure to be manufactured simultaneously with the insulation layer rather than requiring separate precision alignment and attachment steps
Solution Approach 2:
The patent specifies optimized parameters for the micro lens array including curvature radius (R: 0.5-5 μm), height (h: 0.1-5 μm), and FWHM ratios to maximize light extraction efficiency while maintaining manufacturability within standard OLED fabrication capabilities
3Productivity
If the organic light emitting layer is made thinner to improve light extraction, then light emission efficiency improves, but device reliability and lifespan decrease
Solution Approach 1:
The organic light emitting layer maintains its standard thickness in most regions to ensure reliability, while localized thinning is introduced only in specific areas (such as at the bottoms of micro lens structures) where light extraction enhancement is needed, thus balancing efficiency and reliability
Solution Approach 2:
The micro lens array structure in the overcoat layer acts as an intermediary that enhances light extraction without requiring the organic light emitting layer to be thinned, by providing optical pathways that guide light out of the device through the existing layer structure
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 improves outward light emitting efficiency while reducing power consumption by optimizing the light extraction path through the use of carefully designed overcoat layer morphologies, specifically enhancing current efficiency and light emission quantity.
Implementation Method 1
In order to improve the outward light extraction efficiency, a micro lens array (MLA) pattern may be inserted in an overcoat layer
Implementation Method 2
Light emitted from an organic light emitting layer of the organic light emitting device passes through several components of the organic light emitting device to exit from the organic light emitting device
Data Source
AI summary
Provided is an organic light emitting device including an overcoat layer on a substrate, a first electrode disposed on the overcoat layer, an organic light emitting layer disposed on the first electrode and including a convex or concave curve; and a second electrode disposed on the organic light emitting layer.