Ce-doped Nitride Red Phosphor for High-Power White Light
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Solution Overview
Problem
Current high-power white light sources with red phosphors suffer from decreased emission quantum efficiency due to longer emission lifetimes, leading to luminance saturation during high-energy excitation, limiting their use in high-power applications.
Innovation Solution
A light-emitting apparatus utilizing a red phosphor with a Ce luminescent center, excited by green light, which has a nitride or oxynitride host material, achieving high absorption efficiency and reduced energy conversion loss, thereby maintaining high quantum efficiency even at high power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a red phosphor with longer emission lifetime is used to improve color rendering properties, then color reproduction is enhanced, but emission quantum efficiency decreases due to luminance saturation during high-energy excitation
Solution Approach 1:
The patent changes the emission lifetime parameter of the red phosphor by selecting specific phosphor materials with shorter emission lifetimes (e.g., CaAlSiN3:Eu2+ with 0.3-0.5 ms lifetime) compared to conventional red phosphors. This parameter change resolves the contradiction by maintaining color rendering properties while preventing luminance saturation and preserving high emission quantum efficiency under high-power excitation conditions.
2Illumination intensity
If high-power excitation is applied to increase output light intensity, then brightness is improved, but luminance saturation occurs in phosphors with longer emission lifetimes
Solution Approach 1:
The patent modifies the emission lifetime parameter of the red phosphor to be shorter (0.1-1 ms range), which enables the phosphor to handle high-power excitation without luminance saturation. This allows the system to operate at high output light intensities while maintaining stable performance and avoiding the saturation effects that plague conventional long-lived red phosphors under high-power conditions.
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 provides a high-power, color-controllable light-emitting apparatus with improved quantum efficiency and color rendering properties, capable of producing white light with good reproducibility and reduced luminance saturation.
Implementation Method 1
The red phosphor is excited by at least part of the green light to emit second light. The second light has a spectrum with a peak wavelength in the range of 600 to 700 nm.
Implementation Method 2
achieving high absorption efficiency and reduced energy conversion loss, thereby maintaining high quantum efficiency even at high power
Data Source
Figure 1A~1B
Figure 2~3
Figure 4~5
AI summary
A light-emitting apparatus includes a solid-state light source and a wavelength conversion device. The solid-state light source emits first light of 480 to 550 nm or 430 to 470 nm. The wavelength conversion device contains a red phosphor with a Ce luminescent center. The red phosphor is excited by at least part of the green light to emit second light. The second light has a spectrum with a peak wavelength in the range of 600 to 700 nm.