Resonance Auxiliary Layer Micro-Cavity Light Extraction
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Solution Overview
Problem
Cosmetic treatment lighting devices face challenges in achieving high light output while minimizing heat generation to prevent skin burns, particularly when used for extended periods close to the skin.
Innovation Solution
A light emitting device with a substrate, a first electrode, an organic material layer including a first resonance auxiliary layer with specific compounds (HAT-CN and NPB) and a second electrode, which utilizes a micro-cavity effect to enhance light output while maintaining low driving voltage and reducing heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the light output is increased to achieve effective cosmetic treatment, then the treatment effectiveness is improved, but the heat generation increases causing skin burns
Solution Approach 1:
The organic material layer is segmented into multiple functional layers including resonance auxiliary layers, electron transport layers, and light emitting layers. This segmentation allows optimization of each layer's thickness and material properties to enhance light output while distributing heat generation across different layers, reducing peak temperatures that cause skin burns.
Solution Approach 2:
The patent changes the thickness parameter of the resonance auxiliary layer to 20-90% of the total organic material layer thickness, and selects materials with specific HOMO/LUMO levels. These parameter changes optimize the micro-cavity effect for enhanced light output while maintaining lower operating voltages that reduce heat generation, resolving the contradiction between light intensity and heat.
2Illumination intensity
If the organic material layer thickness is increased to improve light output through micro-cavity effect, then the light extraction efficiency is improved, but the driving voltage increases leading to more heat generation
Solution Approach 1:
Different regions of the organic material layer are assigned different qualities: the resonance auxiliary layers use materials with specific HOMO/LUMO levels optimized for charge transport, while the light emitting layers use materials optimized for light emission. This local quality differentiation allows the thick resonance auxiliary layers to enhance light output without proportionally increasing driving voltage, as each layer performs its specialized function efficiently.
Solution Approach 2:
The patent employs composite material structures combining resonance auxiliary materials (e.g., Alq3, BCP) with light emitting materials (e.g., CdSe, CdS quantum dots). This composite approach creates a synergistic effect where the resonance auxiliary layers enhance light extraction through micro-cavity effects while the overall structure maintains optimized charge transport pathways, achieving high light output at reduced driving voltages.
3Illumination intensity
If the resonance auxiliary layer thickness is increased to enhance micro-cavity effect, then the light extraction efficiency is improved, but the device complexity increases
Solution Approach 1:
The resonance auxiliary layers serve multiple functions simultaneously: they provide the micro-cavity effect for enhanced light extraction, facilitate charge transport through their specific HOMO/LUMO levels, and contribute to the overall device stability. This multi-functionality reduces device complexity by combining what could be separate components into unified layers that perform multiple roles.
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 device achieves improved light output and suppressed heat generation, enabling effective cosmetic treatment with reduced risk of skin burns, even at lower driving voltages and current densities.
Implementation Method 1
introducing a resonance auxiliary layer thick enough to achieve an effect of improved light output due to micro-cavity effect
Data Source
AI summary
A light emitting device includes a substrate; a first electrode disposed on the substrate; an organic material layer disposed on the first electrode and including a first resonance auxiliary layer; and a second electrode disposed on the organic material layer, wherein the first resonance auxiliary layer includes a first compound with a lowest unoccupied molecular orbital (LUMO) level of −4 eV or less and a second compound with a highest occupied molecular orbital (HOMO) level of −4 eV or less, and wherein the first resonance auxiliary layer has a thickness of 20% to 90% of a total thickness of the organic material layer.