Quantum Dot Lighting with Encapsulant Layers
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Solution Overview
Problem
Existing solid state lighting devices using quantum dots face degradation issues due to photo-oxidation and incompatibility with conventional LED manufacturing processes, leading to reduced brightness and poor color quality.
Innovation Solution
A solid state lighting device is developed with a light source and an active layer comprising quantum dots dispersed in a cross-linked polymer or silicone matrix, along with non-absorbing light scattering dielectric particles, and encapsulant layers to protect the quantum dots from degradation and enhance light mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If quantum dots are used in conventional LED manufacturing processes, then color quality and brightness are improved, but photo-oxidation degradation occurs reducing longevity
Solution Approach 1:
An encapsulant layer is introduced as an intermediary between the quantum dots and the external environment. This encapsulant protects the quantum dots from photo-oxidation while allowing them to maintain their light-emitting properties, thus resolving the contradiction between brightness and longevity
Solution Approach 2:
The patent uses composite material structures including the quantum dots dispersed in a matrix material and covered by an encapsulant layer. This composite structure provides both the optical performance needed for brightness and the protective function needed for longevity
2Illumination intensity
If phosphor powder is combined with epoxy or silicone encapsulant, then white light is generated, but color quality is poor with limited color temperature range
Solution Approach 1:
The patent changes the key parameter from using broad-spectrum phosphors to using quantum dots with size-tunable emission wavelengths. By controlling the size of quantum dots, precise color temperatures and high color quality can be achieved while maintaining ease of manufacture through solution processing
3Quantity of substance
If phosphors with narrow absorption spectra are used, then specific wavelength conversion is achieved, but adaptability to different LED wavelengths is limited
Solution Approach 1:
Quantum dots provide universal adaptability to different LED wavelengths. By adjusting the size of quantum dots, they can be tuned to absorb and emit at various wavelengths, making them compatible with different LED chip wavelengths (blue, violet, ultraviolet) while maintaining high conversion efficiency
4Ease of manufacture
If quantum dots are applied without protective encapsulation, then manufacturing simplicity is maintained, but photo-oxidation degradation reduces brightness
Solution Approach 1:
A thin film encapsulant layer is applied over the quantum dots. This thin protective layer prevents photo-oxidation degradation and maintains brightness stability while being compatible with conventional LED manufacturing processes, thus resolving the contradiction between manufacturing simplicity and brightness stability
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 solution maintains initial quantum yield, protects quantum dots from photo-oxidation, and is compatible with conventional manufacturing processes, resulting in stable and efficient light emission with improved color quality and longevity.
Implementation Method 1
Quantum dots are tiny crystals of II-VI, III-V, IV-VI materials that have a diameter between 1 nanometer (nm) and 20 nm. In the strong confinement limit, the physical diameter of the quantum dot is smaller than the bulk excitation Bohr radius causing quantum confinement effects to predominate.
Implementation Method 2
Existing solid state lighting devices using quantum dots face degradation issues due to photo-oxidation and incompatibility with conventional LED manufacturing processes
Implementation Method 3
non-absorbing light scattering dielectric particles, and encapsulant layers to protect the quantum dots from degradation and enhance light mixing
Data Source
AI summary
Solid state lighting devices containing quantum dots dispersed in polymeric or silicone acrylates and deposited over a light source. Solid state lighting devices with different populations of quantum dots either dispersed in matrix materials or not are also provided. Also provided are solid state lighting devices with non-absorbing light scattering dielectric particles dispersed in a matrix material containing quantum dots and deposited over a light source. Methods of manufacturing solid state lighting devices containing quantum dots are also provided.