Low-Boron Red Phosphor Composition for Narrower LED Emission
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Solution Overview
Problem
Current phosphors used in light-emitting devices, particularly those emitting red light, face issues with boron contamination leading to deteriorated light emission characteristics and a need for improved emission intensity and conversion efficiency, with existing red phosphors having broad spectrum half widths and potential environmental concerns.
Innovation Solution
A phosphor with a specific crystal phase composition and controlled boron content, where the boron content is limited to a value of Log10(b) of 3.5 or less, is used, along with a light-emitting device configuration that includes this phosphor, to achieve a favorable emission peak wavelength and narrow spectrum half width, enhancing emission intensity and color rendering capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a boron nitride crucible is used for phosphor synthesis, then the synthesis process is easier and the crucible has good chemical stability, but boron mixes into the phosphor and deteriorates light emission characteristics
Solution Approach 1:
A coating layer comprising at least one of a metal element or a metal nitride is formed on the inner surface of the boron nitride crucible. This coating layer acts as an intermediary barrier between the boron nitride crucible and the phosphor, preventing direct contact and boron mixing while maintaining the chemical stability and ease of synthesis process.
2Adaptability or versatility
If S/CASN phosphors are used, then the phosphor can be applied to light-emitting devices, but the emission spectrum has broad half width (80-90 nm) and includes low luminosity function regions, reducing conversion efficiency
Solution Approach 1:
The patent modifies the phosphor composition by adjusting the ratio of Al to (Si+Al) within 5-20 at%, and controlling the Eu concentration at 0.5-5 at%. These parameter changes result in a narrower emission spectrum half width (50-70 nm) while maintaining applicability to light-emitting devices, thereby improving conversion efficiency by reducing energy loss in low luminosity function regions.
3Adaptability or versatility
If KSF phosphor is used, then the phosphor can be used in light-emitting devices, but it is harmful as a Mn-activated compound, posing health and environmental risks
Solution Approach 1:
The patent changes the activation mechanism from Mn-activated to Eu-activated phosphor. By using europium as the activator instead of manganese, the phosphor maintains its usability in light-emitting devices while eliminating the harmful effects associated with Mn-activated compounds, thus resolving the health and environmental concerns.
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 phosphor with improved emission peak wavelength, narrow spectrum half width, and high emission intensity, resulting in light-emitting devices with enhanced color rendering and conversion efficiency for applications in illumination, image display, and vehicle indicator lamps.
Implementation Method 1
a phosphor including: a crystal phase having a composition represented by formula (1)
Implementation Method 2
Higher emission efficiency for LEDs is sought, and a phosphor having superior light emission characteristics
Data Source
AI summary
A phosphor includes a crystal phase having a composition represented by RexMAaMBbMCcDdXe, in which MA includes at least one of Ca, Sr, Ba, Na, K, Y, Gd, or La, MB includes at least one of Li, Mg, or Zn, MC includes at least one of Al, Si, Ga, In, or Sc, D is N (nitrogen) and/or O (oxygen), X includes at least one of F, Cl, Br, or I, Re includes at least one of Eu, Ce, Pr, Tb, or Dy, and a, b, c, d, e, and x satisfy the specific expressions, respectively. In the phosphor, when a content of B (boron) is designated as b (mass ppm), a value of Log10(b) is 3.5 or less.