Inverted-Conical Insulating Layer for OLED Light Extraction
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Solution Overview
Problem
Organic electroluminescence display devices face issues with light extraction efficiency and extraneous light reflections, leading to reduced luminance and difficulty in viewing display images due to the limitations of circularly polarizing plates, which have a theoretical transmittance of 50% or less.
Innovation Solution
The configuration includes a light-shielding layer positioned to overlap the light-emitting region, with an insulating layer having openings and inverted-conical or inverted-pyramidal depressions to reflect and transmit light effectively, reducing reflections and enhancing light extraction efficiency without the need for a circularly polarizing plate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a circularly polarizing plate is bonded to the substrate to prevent reflections of extraneous light, then reflections of extraneous light are reduced, but light extraction efficiency decreases due to theoretical transmittance of 50% or less
Solution Approach 1:
The solution divides the light management function into multiple components: a light-shielding layer with openings for light extraction, and a separate reflecting member with inverted-conical or inverted-pyramidal cross-section for extraneous light reflection. This segmentation allows each component to optimize its specific function without the energy loss inherent in circularly polarizing plates.
Solution Approach 2:
The reflecting member converts harmful extraneous light reflections into beneficial effects by using total internal reflection at the inverted-conical or inverted-pyramidal surfaces. This structure redirects extraneous light away from the display while maintaining high light extraction efficiency for the display image, effectively transforming the reflection problem into a solution.
2Loss of energy
If a reflecting member with inverted-conical or inverted-pyramidal cross-section is provided, then light extraction efficiency is improved, but device complexity increases
Solution Approach 1:
The reflecting member is integrated directly into the sealing structure of the display device, merging the light reflection function with the existing sealing layer. This integration approach reduces device complexity by eliminating separate components while maintaining the inverted-conical or inverted-pyramidal geometry for effective light extraction.
Solution Approach 2:
The inverted-conical or inverted-pyramidal cross-section introduces a three-dimensional geometric feature to the otherwise planar sealing structure. This dimensional change enables effective light extraction through total internal reflection without requiring additional layers or complex assemblies, as the 3D geometry itself provides the light management function.
3Object-affected harmful factors
If a light-shielding layer is provided to block extraneous light, then reflections are reduced, but manufacturing precision requirements increase
Solution Approach 1:
The light-shielding layer serves multiple functions simultaneously: it blocks extraneous light from reaching the light-emitting elements, provides a structural base for the reflecting member, and defines the opening patterns for light extraction. This multi-functionality reduces the need for separate precision-aligned components, thereby lowering manufacturing precision requirements.
Solution Approach 2:
The light-shielding layer is formed first as part of the sealing structure, establishing the foundation for subsequent light management features. By pre-positioning the light-shielding layer with its openings before adding the reflecting member, the design simplifies alignment requirements as later steps build upon the already-established pattern rather than requiring precise alignment between independently manufactured components.
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 extraction efficiency, reduces power consumption, and maintains constant luminance with less electric power, while minimizing reflections from extraneous light, thus enhancing the overall display performance.
Implementation Method 1
The second insulating layer has an inverted-conical or inverted-pyramidal depression in each region thereof overlapping a corresponding one of the light-emitting regions in a plan view
Implementation Method 2
The light-shielding layer has a first region located in a region overlapping the light-emitting region. The light-shielding layer has a second region located in a region between adjacent ones of the plurality of light-emitting elements
Implementation Method 3
An organic electroluminescence (hereinafter referred to as 'organic EL') display device has light-emitting elements provided in each separate pixel
Data Source
AI summary
A display device includes a first substrate, a light-emitting element over the first substrate, a sealing film over the light-emitting element, a first insulating layer over the sealing film, a second insulating layer over the sealing film, a light-shielding layer over the second insulating layer, and a second substrate over the light-shielding layer. The first insulating layer has an opening in a region thereof overlapping a light-emitting region of the light-emitting element. The second insulating layer has an inverted-conical or inverted-pyramidal depression above the light-emitting region of the light-emitting element. The light-shielding layer is located in a region overlapping the light-emitting region of the light-emitting element.