NIR Phosphor Composition for Low Self-Absorption Light Conversion
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Solution Overview
Problem
Current phosphor materials for near-infrared (NIR) light-emitting devices face challenges such as luminescence quenching at elevated temperatures and self-absorption losses, which reduce efficiency and stability, particularly in applications requiring short light pulses with constant spectral power.
Innovation Solution
Development of NIR phosphors with a wide band gap host lattice, including trivalent cations like Cr(III) and tetravalent cations such as Si4+, which suppress the formation of Cr(IV) and reduce self-absorption, combined with specific crystal structures like calcium gallogermanate, garnet, or colquiirite, to enhance stability and efficiency at elevated temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional phosphor materials are used for NIR light-emitting devices, then the device can operate in the near-infrared range, but luminescence quenching occurs at elevated temperatures and self-absorption losses reduce efficiency
Solution Approach 1:
The patent changes the chemical composition parameters of the phosphor material by incorporating specific cations (Cr3+, Si4+) and controlling the host lattice structure (calcium gallogermanate, garnet, or colquiirite structures). This compositional parameter change increases the band gap to suppress thermal quenching and reduces self-absorption, thereby improving reliability at elevated temperatures while minimizing energy losses
Solution Approach 2:
The patent creates composite phosphor materials by combining specific host lattices (calcium gallogermanate, garnet, or colquiirite structures) with dopant cations (Cr3+, Si4+). This composite approach leverages the synergistic effects of the host structure and dopants to achieve both high thermal stability and reduced self-absorption losses, resolving the contradiction between reliability and energy efficiency
2Use of energy by moving object
If phosphor materials with narrow band gap are used, then absorption efficiency may be higher, but quantum efficiency decreases due to self-absorption losses
Solution Approach 1:
The patent optimizes the band gap parameter of the phosphor material by selecting specific host lattices and dopant combinations. The band gap is engineered to be wide enough to minimize self-absorption losses while maintaining sufficient absorption efficiency for NIR excitation, directly resolving the trade-off between these two energy-related parameters
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 NIR phosphors exhibit improved absorption, quantum efficiency, and stability at elevated temperatures, maintaining high luminescence conversion efficiency and reducing afterglow phenomena, enabling efficient light conversion across the 700-1100 nm range.
Implementation Method 1
NIR phosphors may have a distributed emission intensity within the 700-1100 nm range
Implementation Method 2
NIR phosphors may have a peak wavelength of at least 700 nm and no more than 1100 nm
Data Source
AI summary
Embodiments of the invention include an infrared-emitting phosphor comprising (La,Gd)3Ga5−x−yAlxSiO14:Cry, where 0≤x≤1 and 0.02≤y≤0.08. In some embodiments, the infrared-emitting phosphor is a calcium gallogermanate material. In some embodiments, the infrared-emitting phosphor is used with a second infrared-emitting phosphor. The second infrared-emitting phosphor is one or more chromium doped garnets of composition Gd3−x1Sc2−x2−yLux1+x2Ga3O12:Cry, where 0.02≤x1≤0.25, 0.05≤x2≤0.3 and 0.04≤y≤0.12.