Dye-Sensitized Upconversion Nanophosphor for Near-Infrared Absorption
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Solution Overview
Problem
Conventional upconversion nanophosphors doped with Yb3+ and Nd3+ have narrow absorption bands and low absorbance in the near-infrared region, limiting their ability to emit bright visible light under infrared excitation due to inefficient energy transfer from organic dyes.
Innovation Solution
A dye-sensitized upconversion nanophosphor structure is developed, where an organic dye with a wide absorption band in the 800-nm region is bonded to the surface of a fluoride-based nanoparticle core/shell or core/shell/shell structure, with Nd3+ and Yb3+ dopants in the shell efficiently transferring energy to activator ions in the core for enhanced visible light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional upconversion nanophosphors doped with Yb3+ and Nd3+ are used, then the structure is simple, but the absorption band is narrow and absorbance is low in the near-infrared region
Solution Approach 1:
The patent combines organic dye molecules with inorganic nanophosphor particles to create a composite material system. The organic dye component provides wide absorption band in the near-infrared region, while the inorganic nanophosphor core maintains structural stability and enables upconversion emission. This composite structure resolves the contradiction by integrating materials with complementary properties to achieve both simple overall structure and high near-infrared absorbance.
2Illumination intensity
If organic dye is bonded to nanophosphor surface, then absorbance in near-infrared region increases, but energy transfer efficiency from dye to activator ions is low
Solution Approach 1:
The patent introduces Yb3+ ions as intermediary sensitizers between the organic dye and the activator ions (Er3+, Tm3+, or Ho3+). The energy transfer pathway is designed as: organic dye → Yb3+ ions → activator ions. This intermediary mechanism resolves the contradiction by providing an efficient energy relay system where Yb3+ ions act as a bridge, ensuring high energy transfer efficiency from the dye to the activator ions while maintaining wide near-infrared absorption.
3Device complexity
If only Yb3+ or Nd3+ doping is used, then the nanophosphor structure is simple, but photoluminescence intensity under infrared excitation is low
Solution Approach 1:
The patent applies local quality differentiation by assigning specific functional roles to different dopant ions at different locations within the nanophosphor structure. Yb3+ ions are positioned to handle near-infrared absorption and energy transfer, while activator ions (Er3+, Tm3+, or Ho3+) are positioned to emit specific visible wavelengths. This localized functional assignment resolves the contradiction by optimizing each ion's role to achieve high photoluminescence intensity while maintaining relatively simple doping structure.
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 approach significantly increases the photoluminescence intensity of blue, green, and red light emission under 800-nm infrared light excitation, improving performance in applications like sensors, imaging contrast agents, and displays.
Implementation Method 1
energy of infrared light absorbed by the organic dye may not be efficiently transferred to Yb3+ ions or Er3+ ions
Implementation Method 2
an organic dye with a wide absorption band in the 800-nm region is bonded to the surface
Implementation Method 3
the dopant Nd3+ absorbs 800-nm infrared light and transfers the absorbed energy to Yb3+
Implementation Method 4
transfers the absorbed energy to Yb3+
Implementation Method 5
the co-dopant Yb3+ transfers the absorbed energy to an activator of the core
Implementation Method 6
thereby showing an emission peak in a visible light region
Implementation Method 7
An upconversion nanophosphor is a material absorbing infrared light and emitting ultraviolet and visible light
Data Source
AI summary
Provided is a dye-sensitized upconversion nanophosphor including a core, a first shell surrounding at least part of the core, and an organic dye bonded to a surface of the nanophosphor which has an absorption band ranging from 650 nm to 850 nm and which is excited in a near-infrared region to emit visible light. The dye-sensitized upconversion nanophosphor may be included in a display apparatus, a fluorescent contrast agent, or an anti-counterfeiting code. The organic dye may be an IR-808 dye.