Deep Red Phosphor for High-Efficiency UV LED Excitation
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Solution Overview
Problem
Conventional red phosphors used in white LEDs exhibit low brightness and emission efficiency when excited by long-wavelength UV light, leading to increased manufacturing costs and bulkiness, and fail to meet the demand for high-quality color displays, particularly in deep red phosphors for full HD TVs.
Innovation Solution
A deep red phosphor with the chemical formula (k-x)MgOxAF2GeO2:yMn4+, where k is between 2.8 and 5.0, x is between 0.1 and 0.7, and y is between 0.005 and 0.015, incorporating non-light-emitting components like excessive MgO and AF2, is developed, along with a manufacturing method involving a solid-state reaction, calcining a powder mixture of MgO, AF2, GeO2, and Mn precursor compounds at 1000°C to 1200°C for 4 to 9 hours.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional red phosphors (3.5MgO.0.5MgF2.GeO2:Mn or K5Eu(WO4)6.25) are used for long-wavelength UV LEDs, then the white LED can be manufactured with UV excitation source, but the red phosphor exhibits low brightness and emission efficiency when excited by 400 nm or greater wavelength light
Solution Approach 1:
The patent changes the chemical composition parameters of the red phosphor by incorporating AF2 (where A is Ca, Sr, Ba, or Zn) alongside MgO and GeO2 in specific molar ratios. This compositional parameter change enables the phosphor to achieve high emission efficiency and brightness when excited by 400 nm or greater wavelength light, resolving the limitation of conventional red phosphors.
Solution Approach 2:
The patent creates a composite phosphor material combining multiple components (MgO, AF2, GeO2, and Mn activator) in a specific formulation. This composite structure leverages the synergistic effects of different materials to achieve superior excitation efficiency and emission performance under UV and blue light excitation, overcoming the deficiencies of single-component conventional phosphors.
2Illumination intensity
If a larger amount of red phosphor is added to white LED to compensate for low brightness, then the red color component is improved, but the manufacturing cost increases and the device becomes bulkier
Solution Approach 1:
By optimizing the chemical composition parameters of the red phosphor (specific ratios of MgO, AF2, GeO2, and Mn), the patent achieves high brightness and emission efficiency from a smaller quantity of phosphor material. This eliminates the need to increase phosphor amount, thereby avoiding increased manufacturing complexity and device size while still achieving excellent red color component in white LED.
3Ease of manufacture
If conventional red phosphors are used, then white LED can be manufactured with UV excitation source, but the light-emitting efficiency is low and manufacturing cost is high
Solution Approach 1:
The patent optimizes the chemical composition parameters of the red phosphor to achieve high light-emitting efficiency under UV and blue light excitation. The specific formulation (MgO-k-xAF2.GeO2:yMn with defined ranges for k, x, and y) enables efficient energy conversion, reducing energy loss while maintaining ease of manufacture through solid-state reaction process.
Solution Approach 2:
The patent converts the previously harmful low emission efficiency into a benefit by discovering that the specific compositional formulation enables high efficiency under 400 nm or greater wavelength excitation. This transforms the limitation of using UV excitation sources into an advantage, achieving both ease of manufacture and high light-emitting efficiency.
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 deep red phosphor achieves up to 150% improved light-emitting efficiency compared to conventional phosphors, offering excellent excitation efficiency for UV and blue light, suitable for LED packages and phosphor lamps, enhancing red phosphor efficiency and enabling high-quality color displays.
Implementation Method 1
a deep red phosphor capable of displaying a deep red color... achieves up to 150% improved light-emitting efficiency compared to conventional phosphors, offering excellent excitation efficiency for UV and blue light
Implementation Method 2
calcining the powder mixture by heat-treating the powder mixture at a temperature of 1000° C. to 1200° C. for 4 to 9 hours
Implementation Method 3
a method of manufacturing a deep red phosphor using a solid-state reaction
Data Source
AI summary
Disclosed is a deep red phosphor (600 nm to 670 nm) of Mn activity having a chemical formula of (k-x)MgOxAF2GeO2:yMn4+ where k is a real number between 2.8 and 5.0, x is a real number between 0.1 and 0.7, y is a real number between 0.005 and 0.015, and A is Ca, Sr, Ba, Zn, or a mixture thereof, or a mixture of Mg and at least one of Ca, Sr, Ba and Zn. The deep red phosphor has a high excitation efficiency and thus can be applied to light emitting diode (LED) packages, which uses an ultraviolet (UV) light source or a blue light source as an excitation light source. The deep red phosphor is applied to a phosphor layer of a phosphor lamp such as a cold cathode fluorescence lamp (CCFL) and a flat fluorescent lamp (FFL).