Core-shell microparticles for electroluminescence efficiency
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Solution Overview
Problem
Electroluminescence devices face low light emitting efficiency and extraction efficiency due to total reflection at interfaces and the inherent degradation of organic materials, leading to poor durability and limited theoretical efficiency limits.
Innovation Solution
Incorporating core-shell-type microparticles with a metal microparticle core and an insulating shell in the light emitting region or on its surface to induce plasmon resonance, enhancing light emission and reducing excitation lifetime, while preventing charge trapping and promoting efficient charge flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If metal microparticles are arranged in the light emitting region to enhance light emission through plasmon effect, then light emitting efficiency is improved, but charge trapping occurs and device durability deteriorates
Solution Approach 1:
The patent introduces an insulating shell as an intermediary layer between the metal microparticle core and the light emitting region. This insulating shell prevents direct contact between charges and metal particles, eliminating charge trapping while allowing plasmon resonance to occur. The shell acts as a mediator that enables the beneficial optical effect while blocking the harmful electrical interaction, thus resolving the contradiction between improved light emitting efficiency and maintained device durability
Solution Approach 2:
The patent creates a composite microparticle structure consisting of a metal core surrounded by an insulating shell. This composite structure combines the plasmon-enhancing properties of metal with the charge-blocking properties of insulating materials. The composite microparticle simultaneously achieves both functions: enhancing light emission through the metal core's plasmon resonance while preventing charge trapping through the insulating shell, thus resolving the technical contradiction
2Ease of manufacture
If light is extracted through transparent electrode at normal incidence, then extraction is simple, but total reflection occurs at critical angle and light extraction efficiency is low
Solution Approach 1:
The patent applies local quality by creating spatial variation in the light emitting region through incorporating microparticles with different refractive indices. The microparticles are distributed throughout the light emitting region, creating local variations in optical properties that enable light extraction at various angles and positions, thus improving overall extraction efficiency while maintaining structural simplicity
Solution Approach 2:
The patent changes the optical parameters of the light emitting region by incorporating microparticles with specific refractive indices and sizes. These parameter changes modify the local refractive index distribution, enabling more effective light extraction by reducing total reflection effects and allowing light to escape at a broader range of angles, thereby improving extraction efficiency
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
Significantly improves light emission efficiency and durability by reducing excitation lifetime and enhancing plasmon-induced light emission, overcoming the limitations of existing technologies.
Implementation Method 1
The microparticle induces plasmon resonance on the surface thereof by light emitted from the light emitting layer
Data Source
Figure 1~3
Figure 4~5
AI summary
High light transmission efficiency is achieved in an electroluminescence device (1) without lowering the durability of the device. The electroluminescence device (1) includes: electrodes (11, 16); a plurality of layers (13 to 15) that are deposited one on another between the electrodes (11, 16); and a light emitting region (14) between the plurality of layers (13 to 15). The light emitting region (14) emits light by application of an electric field between the electrodes (11, 16). At least one microparticle (20) that induces plasmon resonance on the surface thereof by the light emitted from the light emitting region (14) is arranged in the vicinity of the light emitting region (14) or in the light emitting region (14). The microparticle (20) is a core-shell-type microparticle including at least one metal microparticle core (22) and an insulation shell (21) that covers the at least one metal microparticle core (22).