Nitride Phosphor for High Color Rendering White LEDs
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Solution Overview
Problem
Current white light LEDs using YAG phosphors have high color temperature and low color rendering index due to red light deficiency, and SrLiAl3N4 phosphors face industrial challenges with low luminous efficiency, failing to meet the demands of semiconductor lighting and display applications with broad color gamut requirements.
Innovation Solution
A nitride phosphor doped with Ba and coexisting Eu2+ and Eu3+ activators, with a formula of (Sr1-x, Bax)LiAl3N4-nOn:Eu3+y, Eu2+z, which emits light with a peak wavelength between 610 nm to 710 nm when irradiated by blue light, enhancing color rendering index and purity, and can be combined with blue light LEDs and other wavelength conversion materials to form high color rendering index white light emitting devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If YAG phosphor is used for white light LED, then the emission spectrum is broad, but the color rendering index is low and color temperature is high due to red light deficiency
Solution Approach 1:
The patent uses a composite phosphor system combining YAG:Ce3+ phosphor (providing broad emission spectrum) with red phosphor materials (CaAlSiN3:Eu2+ or Sr2Si5N8:Eu2+) to create a composite material that maintains the broad spectrum while adding strong red emission components to improve color rendering index and adjust color temperature
Solution Approach 2:
The patent merges multiple phosphor materials with different emission characteristics into a single phosphor layer or combination system, where YAG:Ce3+ provides yellow-green emission and red phosphors provide red emission, combining their advantages to achieve both broad spectrum and high color rendering
2Stability of the object's composition
If SrLiAl3N4 phosphor is used, then the wavelength is suitable and temperature stability is high, but the luminous efficiency is low
Solution Approach 1:
The patent modifies the composition parameters of SrLiAl3N4 phosphor by doping with transition metal elements (Mn2+, Fe2+, Co2+, Ni2+) or rare earth elements (Eu2+, Dy3+), changing the electronic structure and energy levels to improve luminous efficiency while maintaining the inherent temperature stability of the nitride phosphor structure
Solution Approach 2:
The patent introduces localized dopant atoms at specific lattice sites within the SrLiAl3N4 crystal structure, creating local electronic states that enhance luminescence efficiency while the overall crystal structure maintains its high temperature stability
3Manufacturing precision
If red phosphor is added to YAG phosphor system, then the color rendering index improves, but the device complexity increases
Solution Approach 1:
The patent segments the phosphor system into distinct functional components (YAG:Ce3+ for broad spectrum, red phosphor for color rendering) that can be separately optimized and then combined, allowing independent control of each phosphor's properties while achieving overall performance improvement
Solution Approach 2:
The patent uses a host matrix material or binder as an intermediary to combine multiple phosphor particles, facilitating energy transfer between phosphors while simplifying the manufacturing process by providing a single-phase hosting environment for multiple phosphor components
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 nitride phosphor achieves high light emission intensity and narrow FWHM, expanding the color gamut and providing red light emitting devices with improved color rendering index, and when combined with blue light LEDs and other materials, forms white light emitting devices with enhanced color rendering index.
Implementation Method 1
the nitride phosphor emits light having a peak wavelength in a range from about 610 nm to about 710 nm upon being irradiated by light having a peak wavelength in a range from about 400 nm to about 500 nm
Data Source
AI summary
A nitride phosphor, and a light emitting device and a backlight module employing the nitride phosphor. The nitride phosphor has the formula (Sr1-x, Bax)LiAl3N4-nOn:Eu3+y, Eu2+z with 0<x<1 and y/z>0.1. The light emitting device includes a light emitting diode configured to emit a first light and the nitride phosphor configured to convert a portion of the first light to a second light. A backlight module includes a printed circuit board and a plurality of the light emitting devices.