Uneven Layer Furrows for Light Extraction in Display Devices
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Solution Overview
Problem
Light emitting display devices face reduced brightness and increased power consumption due to low light extraction efficiency, primarily caused by total reflection at interfaces between the light emitting layer and electrodes or the substrate and air.
Innovation Solution
Incorporating a wavelength conversion layer overlapping the light emitting element and an uneven layer with furrows, where the shortest distance between the bottom surface of the furrows and the wavelength conversion layer is 0.1 um or greater, to alter the light's traveling path and enhance extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a light emitting display device uses a conventional flat structure without an uneven layer, then the device structure is simple and easy to manufacture, but the light extraction efficiency is low causing reduced brightness and increased power consumption
Solution Approach 1:
The patent introduces an uneven layer with furrows (curved/irregular surfaces) between the light emitting element and wavelength conversion layer. This curved surface structure modifies light propagation paths and reduces total internal reflection at interfaces, thereby improving light extraction efficiency without significantly complicating the manufacturing process.
Solution Approach 2:
The uneven layer creates a micro-structured interface with furrows that effectively increases the surface area and creates multiple light extraction pathways. This micro-structuring approach类似于porous material principles by providing numerous interfaces for light to escape, improving extraction efficiency while maintaining manufacturing feasibility.
2Loss of energy
If the uneven layer is placed very close to the wavelength conversion layer to maximize light extraction, then light extraction efficiency improves, but the wavelength conversion layer may be damaged or its properties degraded
Solution Approach 1:
The uneven layer serves as an intermediary structure between the light emitting element and the wavelength conversion layer. It is positioned at an optimized distance (0.1-3.0 μm) to effectively extract light while preventing direct contact that could cause damage. The uneven structure provides mechanical separation while maintaining optical coupling benefits.
Solution Approach 2:
The patent optimizes the distance parameter between the uneven layer and wavelength conversion layer to a specific range (0.1-3.0 μm). This parameter optimization balances two competing requirements: being close enough to maximize light extraction efficiency while being far enough to prevent damage to the wavelength conversion layer, thus resolving the contradiction.
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, leading to increased brightness and reduced power consumption while preventing property degradation of the light emitting element by maintaining a sufficient distance between the uneven layer and the wavelength conversion layer.
Implementation Method 1
an uneven layer that includes a plurality of furrows between the light emitting element and the wavelength conversion layer
Implementation Method 2
a part of a light emitted at the light emitting layer is not output to the outside due to a total reflection at an interface between the light emitting layer and the electrode or an interface between a substrate and an air
Data Source
AI summary
A light emitting display device includes: a light emitting element that includes a light emitting layer between a first electrode and a second electrode; a wavelength conversion layer overlapping the light emitting element; and an uneven layer that includes a plurality of furrows between the light emitting element and the wavelength conversion layer, wherein a shortest distance between a bottom surface of the plurality of furrows and the wavelength conversion layer is 0.1 um or greater.