Cr3+ Doped Phosphor Near-Infrared Light Emitter for ICG
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Solution Overview
Problem
The existing light emitting devices for exciting ICG (indocyanine green) have low excitation efficiency due to the asymmetrical absorption spectrum of ICG and limited overlap with the fluorescence spectrum of conventional phosphors, resulting in inefficient conversion of near-infrared light.
Innovation Solution
A light emitting device with a wavelength converter containing a first phosphor that absorbs primary light and emits near-infrared light with a broad fluorescent component based on the 4T2→4A2 electron energy transition of Cr3+, optimizing the fluorescence spectrum to have a maximum value within 700-800 nm and a half-width of less than 100 nm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional phosphors are used to convert light to near-infrared for ICG excitation, then the device structure is simple, but the excitation efficiency of ICG becomes low due to limited spectral overlap
Solution Approach 1:
The patent changes the spectral parameters of the phosphor by selecting specific materials (CaAlSiN3 host with Eu2+ and Cr3+ dopants) to achieve a fluorescence spectrum with a maximum at 700-800 nm and a half-width of 80-120 nm, optimizing the overlap with ICG's absorption spectrum while maintaining device simplicity
Solution Approach 2:
The patent uses a composite phosphor material combining CaAlSiN3 host matrix with dual dopants (Eu2+ at 0.03-0.07 atomic ratio and Cr3+ at 0.003-0.01 atomic ratio) to achieve both the desired spectral characteristics and high excitation efficiency without complicating the device structure
2Reliability
If the fluorescence spectrum half-width is reduced to improve ICG excitation efficiency, then the spectral overlap with ICG absorption increases, but the manufacturing precision requirements become more stringent
Solution Approach 1:
The patent optimizes the dopant concentration parameters (Eu2+ at 0.03-0.07 and Cr3+ at 0.003-0.01 atomic ratios) to achieve a fluorescence half-width of 80-120 nm, which provides sufficient spectral overlap with ICG while being manufacturable with standard precision
Solution Approach 2:
The patent enhances the spectral quality in the critical 700-800 nm region by using Cr3+ dopant which emits in this specific range, creating a localized high-intensity region that matches ICG's absorption peak without requiring ultra-precise control over the entire spectrum
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 device achieves high ICG excitation efficiency by emitting near-infrared light that effectively excites ICG, enhancing the detection accuracy of tumors in medical applications and improving the therapeutic effect in cosmetic and medical systems.
Implementation Method 1
a first phosphor that absorbs the primary light and emits first wavelength-converted light, wherein the light emitting device emits output light including the first wavelength-converted light, the first wavelength-converted light is near-infrared light having a fluorescence intensity maximum value within a wavelength range of 700 nm or more and less than 800 nm
Implementation Method 2
the first wavelength-converted light mainly contains a broad fluorescent component based on an electron energy transition of 4T2→4A2 of Cr3+
Implementation Method 3
a wavelength converter that includes a first phosphor that absorbs the primary light and emits first wavelength-converted light
Data Source
AI summary
Provided is a light emitting device including a light source that emits primary light; and a wavelength converter that includes a first phosphor that absorbs the primary light and emits first wavelength-converted light, wherein the light emitting device emits output light including the first wavelength-converted light, the first wavelength-converted light is near-infrared light having a fluorescence intensity maximum value within a wavelength range of 700 nm or more and less than 800 nm, the first wavelength-converted light mainly contains a broad fluorescent component based on an electron energy transition of 4T2→4A2 of Cr3+, and the broad fluorescent component has a fluorescence spectrum half-width that is less than 100 nm.