Down-shifting nanophosphors, method for preparing the same, and luminescent solar concentrator using the same
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Solution Overview
Problem
Conventional luminescent solar concentrators (LSCs) require materials that absorb near infrared rays and emit infrared rays with a wavelength of 800-1000 nm, but existing nanophosphors are not suitable due to size and scattering issues, limiting their efficiency in transparent solar cell modules.
Innovation Solution
Development of down-shifting nanophosphors with a core-shell-shell structure, specifically NaY1-x-yF4:Nd3+x,Yb3+y, that absorb near infrared rays with a wavelength of 700-900 nm and emit near infrared rays with a wavelength of 950-1050 nm, allowing for efficient energy transfer in transparent LSC films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional powder phosphors are used in LSC films, then light absorption and emission functions are achieved, but light scattering occurs and transparency is compromised
Solution Approach 1:
The patent applies parameter changes by reducing phosphor particle size to the nanoscale (60 nm or less) and optimizing doping concentrations (Nd3+: 0.05-0.5, Yb3+: 0.05-0.5). This size reduction eliminates light scattering while maintaining absorption and emission efficiency, directly resolving the contradiction between light absorption function and light scattering harm.
Solution Approach 2:
The patent uses composite materials by creating a core-shell-shell structure with NaYF4 matrix and doped lanthanoid elements (Nd3+, Yb3+). This composite structure enables simultaneous achievement of near-infrared absorption, infrared emission, and transparency by combining multiple functional components at the nanoscale.
2Object-affected harmful factors
If nanophosphors with size of 60 nm or less are used to achieve transparency, then light scattering is reduced, but near infrared ray emission efficiency is insufficient
Solution Approach 1:
The patent resolves this contradiction by developing a composite nanophosphor system with specific composition (NaY1-x-yF4:Nd3+x,Yb3+y) where x and y are optimized. The composite structure with dual dopants enables efficient near-infrared absorption and infrared emission even at 60 nm size, overcoming the limitation of conventional single-material nanophosphors.
Solution Approach 2:
The patent applies local quality by creating non-uniform doping distribution within the nanophosphor structure. The core-shell-shell architecture provides different chemical environments in different regions, optimizing both light absorption and emission properties while maintaining small size for transparency.
3Loss of energy
If luminescence materials are designed to absorb near infrared rays and emit infrared rays of 800-1000 nm, then energy transfer to silicon solar cells is improved, but material size must be significantly small which limits available materials
Solution Approach 1:
The patent resolves this contradiction by designing a composite nanophosphor with tailored composition (NaY1-x-yF4:Nd3+x,Yb3+y). This composite approach provides precise control over absorption and emission wavelengths, enabling optimal energy transfer to silicon solar cells while maintaining small size. The compositional flexibility of composite materials overcomes the limitation of available materials with specific size requirements.
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 down-shifting nanophosphors with a size of 60 nm or less enhance the near infrared ray shifting efficiency, enabling the creation of transparent solar cell modules with improved light transfer and high transmittance, surpassing the limitations of conventional materials.
Implementation Method 1
when lanthanoid elements are partially doped, excitation is generated by near infrared rays, and then infrared rays having a larger wavelength (lower energy) as compared to the excitation light are emitted. This case is referred to as down-shifting light emission
Implementation Method 2
luminescence of nanophosphors occurs due to a 4f-4f electron shift in the trivalent lanthanoid ion doped to the matrix
Implementation Method 3
the light input to the window portion arrives at the silicon solar cell disposed at the edge of the window through total reflection
Data Source
AI summary
The present disclosure relates to down-shifting nanophosphors, a method for preparing the same, and a luminescent solar concentrator (LSC) using the same. The down-shifting nanophosphors according to an embodiment of the present disclosure include a core including NaYF4 nanocrystals doped with neodymium (Nd) and ytterbium (Yb), and further include a neodymium (Nd)-doped crystalline shell surrounding the core, or further include a NaYF4 crystalline shell surrounding the crystalline shell. Therefore, the down-shifting nanophosphors efficiently absorb near infrared rays with a wavelength range of 700-900 nm and efficiently emit near infrared rays with a wavelength range of 950-1050 nm. In addition, the down-shifting nanophosphors according to an embodiment of the present disclosure has a size of 60 nm or less, and thus can be applied to manufacture transparent LSC films with ease and can realize transparent solar cell modules having high near infrared ray shifting efficiency.