Nitride Blue Phosphor for White LED Color Rendering
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Solution Overview
Problem
Conventional white LED backlights using a combination of blue LEDs and yellow phosphors suffer from efficiency degradation and poor color rendering due to quantum deficits and reradiation inefficiencies, lacking green and red components, which limits their application beyond cellular phone and laptop displays.
Innovation Solution
A light emitting device incorporating a blue phosphor with a novel composition, LaxOySi6Al4N12:Ce3+, that absorbs visible light in the range of 350-370 nm and emits in the range of 465-473 nm, along with additional red and green phosphors to enhance brightness and luminescence intensity, improving color representation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a blue LED and yellow phosphor combination is used to create white light, then the device is easy to drive and inexpensive, but the efficiency is degraded due to quantum deficits and reradiation efficiency loss
Solution Approach 1:
The patent changes the phosphor material parameters by using a nitride phosphor (LaxOySi6Al4N12:Ce3+) instead of conventional yellow phosphor, which has different optical and structural properties that reduce quantum deficits and improve reradiation efficiency while maintaining ease of manufacture
Solution Approach 2:
The patent employs a composite phosphor system combining nitride phosphor with specific compositional ratios (LaxOySi6Al4N12:Ce3+) to achieve superior light conversion efficiency while maintaining the simplicity and low cost of LED-based white light generation
2Device complexity
If a blue LED and yellow phosphor combination is used, then the device structure is simple, but the color rendering is poor due to lack of green and red components
Solution Approach 1:
The patent changes the emission spectrum parameters by selecting a nitride phosphor with peak emission in the blue-green region (465-475 nm), which fills the spectral gap between blue LED and red regions, improving color rendering while maintaining a simple two-component structure
Solution Approach 2:
The patent applies local quality enhancement by using a phosphor with tailored emission characteristics that specifically addresses the missing green spectral region, thereby improving overall color rendering without adding complex multi-phosphor systems
3Ease of manufacture
If conventional phosphor materials are used, then the manufacturing process is established, but the reliability is inferior due to moisture sensitivity of silicate phosphor
Solution Approach 1:
The patent employs a composite nitride phosphor material (LaxOySi6Al4N12:Ce3+) that combines the benefits of established phosphor manufacturing processes with superior moisture resistance inherent to the nitride crystal structure, achieving both ease of manufacture and high reliability
Solution Approach 2:
The patent replaces moisture-sensitive silicate phosphor with a more stable nitride phosphor that has comparable or lower manufacturing cost but significantly extended operational life and reliability under humid conditions
4Illumination intensity
If phosphor is exposed to high energy excitation source, then the phosphor can emit visible light, but the luminance of the phosphor is reduced over time
Solution Approach 1:
The patent changes the phosphor's structural and compositional parameters by using a nitride-based crystal structure with specific stoichiometry (LaxOySi6Al4N12:Ce3+), which exhibits enhanced photostability and resistance to luminance degradation under continuous high-energy excitation
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 white LED with improved brightness, luminescence intensity, and color rendering, enabling broader applications beyond traditional display uses by effectively addressing efficiency and color representation issues.
Implementation Method 1
a blue phosphor with a novel composition, LaxOySi6Al4N12:Ce3+, that absorbs visible light in the range of 350-370 nm and emits in the range of 465-473 nm
Data Source
AI summary
Disclosed are a phosphor and a light emitting device including the same. The light emitting device includes a light emitting chip, a phosphor layer on the light emitting chip, and a phosphor added into the phosphor layer to absorb a light emitted from the light emitting chip and emit a central wavelength having a first blue color. The phosphor has a composition formula of LaxOySi6Al4N12:Ce3+z, a range of the x is 2≤x≤8, and a range of the y is 3≤y≤12.