Electroluminescent Display Light Extraction via Protrusions
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Solution Overview
Problem
Electroluminescent display devices suffer from low light extraction efficiency due to surface plasmon components and optical waveguide modes, leading to trapped light within the device, which degrades image quality and reduces the effectiveness of the display.
Innovation Solution
The implementation of a micro lens structure with protrusions and air gaps in the overcoat layer, where a high-viscosity material layer is applied on the protrusions, creating a refractive index contrast that guides light out of the device, enhancing extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional flat structure is used in the electroluminescent display device, then the device structure is simple and easy to manufacture, but light extraction efficiency is degraded due to trapped light in surface plasmon components and optical waveguide modes
Solution Approach 1:
The patent introduces protrusions with curved surfaces into the overcoat layer to replace the conventional flat structure. These curved protrusions act as microlens arrays that focus and extract trapped light from surface plasmon and waveguide modes, improving light extraction efficiency without significantly complicating the manufacturing process
Solution Approach 2:
The patent modifies the refractive index distribution by introducing protrusions with different heights and materials (including air gaps). This parameter change creates optical path differences that convert trapped light modes into extractable light, thereby improving light extraction efficiency
2Loss of energy
If protrusions are added to improve light extraction efficiency, then light extraction efficiency is improved, but device complexity increases
Solution Approach 1:
The overcoat layer is segmented into multiple protrusions with different heights and materials rather than using a uniform structure. This segmentation allows each protrusion to function as an independent microlens, collectively improving light extraction efficiency while maintaining a modular design that doesn't excessively increase device complexity
Solution Approach 2:
The patent uses composite structures combining different materials (organic materials, inorganic materials, and air gaps) within the protrusions. This composite approach optimizes optical properties for light extraction while integrating multiple functions into a single layer, balancing performance improvement with 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 configuration significantly improves light extraction efficiency by guiding trapped light out of the device, reducing black areas and enhancing image quality while preventing the occurrence of black spots, thereby improving the overall performance of the electroluminescent display.
Implementation Method 1
a high-viscosity material layer on the plurality of protrusions and the air gap
Implementation Method 2
a charge is injected into an emission layer formed between a cathode, which is an electron-injecting electrode, and an anode, which is a hole-injecting electrode, such that excitons are formed by electrons and holes. Radiative recombination of the excitons occurs such that light is emitted.
Data Source
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AI summary
The present disclosure provides an electroluminescent display device including a substrate including an emissive area and a non-emissive area; a plurality of protrusions over the substrate and in the emissive layer, the plurality of protrusions spaced apart from each other; an air gap between the plurality of protrusions; a high-viscosity material layer on the plurality of protrusions and the air gap; a first electrode disposed on the high-viscosity material layer; an emitting layer on the first electrode; and a second electrode on the emitting layer.