Green Emitting Phosphor Crystal Orientation for High Quantum Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current green emitting phosphors, such as SrGa2S4:Eu, have limitations in light-emitting efficiency when used with near-ultraviolet or blue LEDs, requiring higher internal quantum efficiency to produce sufficient white light for lighting and display applications.
Innovation Solution
A green emitting phosphor with a mother crystal composition of Sr, Ga, and S, doped with Eu2+ as a luminescent center, characterized by specific XRD patterns and molar ratios, enhancing internal quantum efficiency and light emission intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional green emitting phosphors (SrGa2S4:Eu) are used with near-ultraviolet or blue LEDs, then the device can be constructed, but the light-emitting efficiency is insufficient and internal quantum efficiency is limited
Solution Approach 1:
The patent modifies the crystal structure parameters of the SrGa2S4:Eu phosphor by controlling the ratio of diffraction intensities at specific angles (2θ=14-20° and 2θ=21-27°) to be 0.4 or greater. This parameter change in the crystal orientation significantly improves the internal quantum efficiency from conventional levels to above 90%, directly resolving the efficiency limitation.
2Illumination intensity
If more green emitting phosphor is added to increase light emission intensity, then the phosphor emission increases, but the LED light transmission is blocked and overall efficiency decreases
Solution Approach 1:
By changing the crystal orientation parameters (diffraction intensity ratio ≥0.4), the phosphor achieves higher internal quantum efficiency (>90%), which means more of the absorbed LED light is converted to phosphor emission. This allows sufficient light emission intensity to be achieved with less phosphor material, thereby maintaining better LED light transmission and avoiding the trade-off between emission intensity and energy loss.
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 phosphor achieves higher internal quantum efficiency and light-emitting efficiency, enabling the production of more effective white light-emitting devices with improved color rendering properties when combined with LEDs.
Implementation Method 1
a green emitting phosphor which comprises a mother crystal containing Sr, Ga and S and a luminescent center... when a near-ultraviolet LED or a blue LED serving as an excitation source and a phosphor containing the green emitting phosphor are combined to create a white light-emitting device
Data Source
AI summary
A green emitting phosphor is provided, allowing the internal quantum efficiency to be increased. The green emitting phosphor comprises a mother crystal containing Sr, Ga and S, and a luminescent center, characterized in that, in an XRD pattern, the ratio of the diffraction intensity of the maximum peak appearing at diffraction angle 2θ=14 to 20° over the diffraction intensity of the maximum peak appearing at diffraction angle 2θ=21 to 27° is 0.4 or greater.