Pyrosilicate Phosphors for pc-LEDs
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current phosphors for white-emitting LEDs, particularly those using blue-emitting LEDs, face challenges such as sensitivity to blue LED chip variations, lack of red component in emission, and poor thermal stability, which affect color quality and efficiency.
Innovation Solution
Development of pyrosilicate phosphors with specific compositions that can be excited in the near-UV or violet region, offering green emission with tunable emission colors and improved thermal quenching behavior, allowing for better color rendering and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If blue-emitting LEDs are used as the primary light source, then the LED chip can provide high brightness with small electrical power, but the phosphor system becomes sensitive to blue LED chip variations and lacks red component in emission
Solution Approach 1:
The patent changes the excitation wavelength parameter from blue (440-480 nm) to near-UV or violet (370-430 nm) region. This parameter change in the primary light source enables the use of phosphors with absorption bands in the near-UV/violet region, which reduces sensitivity to LED chip variations and allows for better color rendering including red component emission.
2Volume of moving object
If blue-emitting LEDs are used, then compactness is achieved, but thermal stability deteriorates due to operating temperature droop
Solution Approach 1:
The patent changes the operating wavelength parameter from blue to near-UV/violet region. This parameter change exploits the physical phenomenon that near-UV/violet LED chips exhibit significantly reduced operating temperature droop compared to blue LED chips, thereby improving thermal stability while maintaining the compactness advantage of LED technology.
3Ease of manufacture
If phosphors are designed for blue LED excitation, then the absorption matches blue emission, but the color rendering index and efficiency decrease due to Stokes loss
Solution Approach 1:
The patent changes the excitation wavelength parameter from blue to near-UV/violet region. This parameter change reduces the Stokes shift (energy loss) because the wavelength difference between excitation and emission is smaller. The phosphors are designed with absorption bands in the near-UV/violet region that overlap with the primary light source emission, improving quantum efficiency and reducing energy loss.
4Ease of manufacture
If conventional phosphors are used, then the manufacturing process is simple, but the color rendering index and emission quality are insufficient
Solution Approach 1:
The patent employs composite phosphor systems combining multiple phosphor materials with different emission characteristics. These composite phosphor layers are designed to work with near-UV/violet LED excitation, providing enhanced color rendering index and emission quality while maintaining compatibility with existing manufacturing processes.
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 pyrosilicate phosphors provide enhanced thermal stability and tunable emission colors, improving the color rendering index and efficiency of LEDs, particularly when used with near-UV or violet LEDs, by minimizing absorption in the blue region and maximizing absorption in the near-UV or violet region.
Implementation Method 1
Phosphors or conversion phosphors are substances or materials which transform radiation of a certain wavelength range into radiation of a longer wavelength range
Implementation Method 2
The present invention also relates to an emission-converting material comprising the conversion phosphor according to the invention
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The present invention relates to pyrosilicate phosphors, to a process for the preparation thereof and to the use thereof as conversion phosphors. The present invention also relates to an emission-converting material comprising the conversion phosphor according to the invention, and to the use thereof in light sources, in particular pc-LEDs (phosphor converted light emitting devices). The present invention furthermore relates to light sources, in particular pc-LEDs, and to lighting units which comprise a primary light source and the emission-converting material according to the invention.