CdSe Luminescent Microspheres for High Color Gamut LEDs
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Solution Overview
Problem
Current white LED technologies using YAG phosphors lack red light in their emission spectrum, resulting in low color rendering index and high color temperature, and existing phosphors face issues with stability and protection requirements, limiting their application in light conversion materials.
Innovation Solution
The development of cadmium oxide-doped silica microspheres that are treated with a selenium precursor to form luminescent microspheres, which exhibit high fluorescence efficiency and stability, eliminating the need for barrier materials and enabling direct use in light conversion applications like luminescent films and LEDs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If YAG phosphor is used in white LED, then the LED can be manufactured with existing technology, but the color rendering index is low and color temperature is high due to lack of red light
Solution Approach 1:
The patent uses a composite phosphor system combining YAG phosphor (yellow emission) with red phosphor materials to create a multi-component phosphor composition. This composite approach allows the white LED to maintain manufacturability with existing YAG technology while adding red light emission to improve color rendering index and adjust color temperature.
2Adaptability or versatility
If organic fluorescent substances are used, then the emission spectrum can be adjusted, but the stability is poor and the full width at half maxima is large
Solution Approach 1:
The patent employs an inorganic phosphor material as an intermediary converter that absorbs blue light from the LED and converts it to red light emission. This inorganic phosphor mediator provides stable, narrow FWHM emission while maintaining the ability to adjust the overall emission spectrum when combined with YAG phosphor, thus improving both stability and spectral adjustability.
3Illumination intensity
If inorganic quantum dots are used, then the emission spectrum can be optimized, but protection from water and oxygen is required which limits application
Solution Approach 1:
The patent replaces fragile quantum dots requiring complex protection structures with robust inorganic phosphor materials that are inherently stable and do not require barrier films or encapsulation. The inorganic phosphor provides sufficient emission spectrum optimization without the need for additional protection layers, thereby reducing device complexity while maintaining optical performance.
4Reliability
If aluminate and silicate phosphors are used, then thermal and chemical stability is excellent, but the number of available aluminosilicate-based phosphors is limited
Solution Approach 1:
The patent utilizes YAG phosphor, which has proven thermal and chemical stability, and combines it with red phosphor materials to create a universal phosphor composition that can be applied across different white LED applications. This approach maintains the reliability benefits of stable phosphor materials while achieving spectral optimization through the complementary combination with red emission materials.
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 luminescent microspheres achieve fluorescence efficiency of 95% or higher, maintain stability under high-intensity blue light, high temperature, and high humidity conditions, and provide a high color gamut, making them suitable for various LED applications without requiring protective barrier films.
Implementation Method 1
the selenium precursor reacts with the adsorbed organic cadmium to form CdSe
Implementation Method 2
The luminescent microspheres obtained by the method of the present disclosure have high fluorescence efficiency (reaching 95% or higher)
Implementation Method 3
heating a resulting mixture to boiling and keeping a boiling state for 1 min to 30 min so that the microspheres swell at high temperature
Implementation Method 4
the oleic acid penetrates the microspheres to react with CdO to obtain an organic cadmium-adsorbed silica suspension
Data Source
AI summary
Luminescent microspheres and a preparation method thereof are disclosed. The preparation method includes: 1) preparing cadmium oxide-doped silica microspheres; 2) adding the silica microspheres to a mixed solution of octadecene/oleic acid or trioctylamine (TOA)/oleic acid, and heating a resulting mixture to a boiling point so that the microspheres swell at high temperature and the oleic acid penetrates into the microspheres to react with CdO to obtain an organic cadmium-adsorbed silica suspension; and 3) adding a selenium precursor to the obtained organic cadmium-adsorbed silica suspension to obtain the luminescent microspheres, where, the selenium precursor reacts with the adsorbed organic cadmium to form CdSe. The luminescent microspheres provided in the present disclosure have high fluorescence efficiency and prominent stability, require no barrier materials such as barrier films for protection, and can be directly used for light conversion materials with high color gamut such as luminescent films, luminescent plates, Mini-LEDs, and Micro-LEDs.