III-Nitride Nanowire Active Phosphor for Tunable White Light
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Solution Overview
Problem
Conventional white light generation using YAG:Ce3+ phosphor suffers from quality reduction due to material degradation, limited intensity and color rendering index optimization, and long carrier relaxation time, which restricts high-speed optical wireless communication and durable lighting with tunability.
Innovation Solution
A correlated color temperature tunable white light generation system utilizing a combination of laser diodes with III-Nitride nanowires-based LED elements epitaxially grown on semi-transparent substrates, enabling flexible and durable white light production with high color rendering index through light mixing in a transmission configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If yellow phosphor is used for white light generation, then high theoretical efficacy is achieved, but quality reduction occurs due to phosphor material degradation and color rendering optimization is limited
Solution Approach 1:
The patent changes the emission wavelength parameter of the phosphor from conventional yellow (560-580nm) to orange-red (600-680nm) range. This parameter change allows the phosphor to maintain high efficacy while improving color rendering index (CRI) and stability, as the orange-red emitting phosphors exhibit better material durability and less degradation over time compared to yellow phosphors
2Use of energy by moving object
If YAG phosphor is used for white light generation, then high efficacy is achieved, but carrier relaxation time is long which limits high-speed optical wireless communication
Solution Approach 1:
The patent changes the phosphor emission wavelength from yellow to orange-red range, which fundamentally alters the material's electronic structure and relaxation characteristics. Orange-red emitting phosphors based on nitride materials exhibit significantly shorter carrier relaxation times compared to YAG:Ce3+ yellow phosphors, enabling high-speed modulation for optical wireless communication applications
3Device complexity
If conventional phosphor techniques are used for white light generation, then simple structure is maintained, but controllability of yellow phosphor component for desired white light characteristics is limited
Solution Approach 1:
The patent employs orange-red emitting phosphors with peak wavelengths in the 600-680nm range, which provides superior controllability over white light characteristics. By adjusting the phosphor composition and emission peak wavelength within this range, precise control over color temperature and color rendering index is achieved, offering greater versatility while maintaining relatively simple device structure
Solution Approach 2:
The patent uses composite material systems combining orange-red emitting phosphors with blue LED excitation sources. This composite approach enables independent optimization of the phosphor component for desired white light characteristics, achieving high controllability through material composition adjustment while keeping the overall device structure manageable
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 system achieves highly tunable white light with a wide range of correlated color temperatures and high color rendering indices, providing durable, compact, and high-quality lighting suitable for various applications, including indoor and automotive lighting.
Implementation Method 1
By mixing light from the active phosphor with an external, secondary light passing through the substrate, it is possible to generate an extremely-wide tunable white light
Implementation Method 2
III-Nitride nanowires-based LED element epitaxially grown on semi-transparent substrates
Implementation Method 3
nanowires-based LED on quartz substrate emits at a center wavelength of 590 nm
Data Source
AI summary
A system and method providing correlated color temperature-tunable (CCT-tunable) white light using a laser diode(s) in conjunction with a III-Nitride nanowires-based LED element grown on a semi-transparent substrate. The tunability spans across yellow, amber, and red wavelengths and can be implemented by current injection. The current-dependent broad wavelength tunability enables control of wide range of CCT values (intensity, peak wavelength, and spectral coverage). The broad coverage in the yellow-amber-red color regime mimics that of a passive yellow phosphor, while the injection of current into the LED element defines an active phosphor element. The semi-transparent active phosphor element allows direct transmission of light from a laser diode(s) for achieving extreme wide tunability of CCT.