Cyan-Based Phosphor Synthesis for Cost-Effective LEDs
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Solution Overview
Problem
The high cost and complexity of manufacturing light emitting devices using siliconnitride-based or oxynitride-based phosphors due to the need for high-temperature and high-pressure synthesis, as well as the expense of synthetic raw materials, result in increased fabrication costs and complicated processes.
Innovation Solution
A novel phosphor with the chemical formula L x M y C z1 N z2 :A a is developed, where L is an alkaline earth metal or transition metal, M is B, Si, P, S, F, Cl, I, or Se, and A is an alkaline rare earth metal, synthesized using a low-temperature and low-pressure process, and applied in a light emitting device with a light emitting diode chip and substrate, allowing for cost-effective production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silicon nitride-based or oxynitride-based phosphor is used, then the phosphor can be synthesized with good luminescence properties, but the synthesis requires high-temperature and high-pressure environment and expensive raw materials, leading to increased fabrication costs and complicated processes
Solution Approach 1:
The patent changes the synthesis parameters from high-temperature and high-pressure conditions to low-temperature and atmospheric pressure conditions. Specifically, the phosphor is synthesized by sintering at 900-1100°C in an ammonia atmosphere, which is significantly lower than the conventional high-pressure sintering conditions, thereby simplifying the fabrication process while maintaining luminescence properties
Solution Approach 2:
The patent uses inexpensive raw materials such as carbonate, oxide, nitride, or carbide of alkaline earth metals or transition metals, along with ammonia gas as the sintering atmosphere. These are replaced with cheaper alternatives compared to the expensive synthetic raw materials required for conventional silicon nitride-based or oxynitride-based phosphors, reducing fabrication costs
2Reliability
If silicon nitride-based or oxynitride-based phosphor is used, then the phosphor can be synthesized with good luminescence properties, but expensive synthetic raw materials are required, leading to increased fabrication costs
Solution Approach 1:
The patent employs inexpensive starting materials including carbonate, oxide, nitride, or carbide of alkaline earth metals or transition metals, and uses ammonia gas as the sintering atmosphere. These materials are significantly cheaper than the synthetic raw materials required for conventional phosphors, thereby reducing fabrication costs while maintaining luminescence properties through the cyan-based phosphor structure LxMyCz1Nz2:Aa
3Manufacturing precision
If conventional phosphor synthesis methods are used, then the phosphor can be synthesized with required properties, but the process is complicated and not easily prepared at low cost
Solution Approach 1:
The patent simplifies the synthesis process by changing the sintering conditions to atmospheric pressure and relatively low temperature (900-1100°C) in an ammonia atmosphere. This approach maintains the required phosphor properties while making the preparation process easier and more accessible compared to conventional high-pressure synthesis methods
Solution Approach 2:
The patent employs a composite chemical formula LxMyCz1Nz2:Aa where L is an alkaline earth metal or transition metal, M is B, Si, P, S, F, Cl, I, or Se, and A is an alkaline rare earth metal or transition metal. This composite structure with cyan groups (Cz1Nz2) enables the phosphor to achieve required luminescence properties through a simpler synthesis process compared to conventional single-phase phosphors
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 novel phosphor synthesis at low cost and pressure simplifies the fabrication process and reduces expenses for light emitting devices, enabling their production with improved efficiency and cost-effectiveness.
Implementation Method 1
a phosphor excited by light generated from the light emitting diode chip
Data Source
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Figure 5
AI summary
A phosphor and a light emitting device containing the phosphor are provided. According to an embodiment, the phosphor is expressed in a following chemical formula: LxMyCz1Nz2:Aa , where L is chosen in the list consisting of the alkaline earth metals; M is chosen in the list consisting of B, Si, P, S, F, Cl, I, and Se; A is chosen in the list consisting of the rare earth metals; C is carbon; N is nitrogen, and where 0<x≤5, 0<y≤5, 1≤z1≤10, 1≤z2≤10, and 0<a≤1.