Multi-Wavelength LED Stack Structure Without Phosphor Conversion
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Solution Overview
Problem
Existing white light emitting devices require phosphors, which complicate manufacturing, increase production costs, and lead to heat-resistant issues due to the use of resin containing phosphors.
Innovation Solution
A light emitting device comprising a short wavelength light emitting portion, a long wavelength light emitting portion, and a coupling layer, where the long wavelength light emitting portion has more Indium in its active layer, allowing for multi-wavelength light emission without phosphors, such as white light, by combining the short and long wavelength portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If phosphor and resin are used to convert blue light to white light, then white light emission is achieved, but manufacturing complexity increases and production cost increases
Solution Approach 1:
The patent extracts and eliminates the phosphor and resin components from the light emitting device. Instead of using blue LED chips with phosphor coatings, the invention uses LED stacks that directly emit multiple wavelengths including white light, thereby removing the problematic phosphor-resin system that caused manufacturing complexity and cost issues.
Solution Approach 2:
The patent changes the fundamental parameter of light emission by using LED stacks with different indium content to emit different wavelengths directly. By controlling the indium composition in the active layer, the device can emit blue, yellow, or other wavelengths without requiring phosphor conversion, thus simplifying the manufacturing process.
2Illumination intensity
If phosphor-based resin is used for wavelength conversion, then white light is emitted, but heat resistance deteriorates and reliability decreases
Solution Approach 1:
The patent removes the thermally vulnerable phosphor-resin system entirely. The LED stacks are designed to directly emit the required wavelengths without relying on phosphor materials embedded in heat-sensitive resin, thereby eliminating the root cause of heat resistance deterioration and improving overall device reliability.
Solution Approach 2:
The patent employs LED stacks with composite semiconductor structures containing different indium compositions. These composite material structures enable direct emission of multiple wavelengths including white light, replacing the phosphor-resin composite and avoiding its thermal limitations.
3Illumination intensity
If phosphor is added to achieve multi-wavelength emission, then white light is produced, but production cost increases
Solution Approach 1:
The patent extracts and eliminates phosphor materials from the device architecture. By using LED stacks that directly emit multiple wavelengths through controlled indium content, the invention removes the need for expensive phosphor additives and their associated handling, quality control, and assembly processes, thereby reducing production costs.
Solution Approach 2:
The patent changes the approach to multi-wavelength emission by controlling the indium composition parameter in the LED stack active layer. This allows direct emission of different wavelengths (blue, yellow, etc.) without requiring phosphor conversion, simplifying the manufacturing process and reducing material costs.
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 solution simplifies the manufacturing process, reduces costs, and enhances durability by eliminating the need for phosphor-based resins, while achieving efficient multi-wavelength light emission, including white light, with reduced light loss.
Implementation Method 1
Each of the first and second LED stacks includes a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer. The active layer of the long wavelength light emitting portion contains more In than the active layer of the short wavelength light emitting portion, and the short wavelength light emitting portion emits light of a shorter wavelength than that of light emitted from the long wavelength light emitting portion.
Data Source
AI summary
A light emitting device includes a short wavelength light emitting portion, a long wavelength light emitting portion, and a coupling layer combining the short wavelength emitting portion and the long wavelength light emitting portion. Each of the short wavelength light emitting portion and the long wavelength light emitting portion includes a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer. The active layer of the long wavelength light emitting portion contains more Indium (In) than the active layer of the short wavelength light emitting portion, and the short wavelength light emitting portion emits light of a shorter wavelength than that of light emitted from the long wavelength light emitting portion.