Fluoride Phosphor Wavelength Conversion for Display Color Purity
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Solution Overview
Problem
Current light emitting devices using LEDs face challenges in achieving high color purity and reliability, particularly in wavelength conversion for blue and green light emission, leading to suboptimal color reproducibility and efficiency.
Innovation Solution
A light emitting device incorporating a substrate with a light emitting element that emits blue and green light, utilizing fluoride-based phosphors represented by Chemical Formula AxMFy:Mn4+ for wavelength conversion into red light, along with organic or inorganic coating layers and protective layers to enhance moisture resistance and light efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional phosphors are used for wavelength conversion, then device complexity is reduced, but color purity and reliability deteriorate
Solution Approach 1:
The patent employs a composite wavelength conversion structure combining fluoride-based phosphors (CaAlSiN3, Sr2Si5N8) with organic coating layers (epoxy resin, silicone resin) and inorganic protective layers (SiO2, Si3N4). This composite approach achieves superior color purity with FWHM <35nm for blue/green light and <10nm for red light, while maintaining structural integrity and reliability
Solution Approach 2:
The patent applies different materials with specific properties to different regions: fluoride-based phosphors for core wavelength conversion, organic coatings for moisture barrier, and inorganic layers for environmental protection. Each layer is optimized for its specific function, achieving high color purity through localized material properties
2Adaptability or versatility
If multiple light emitting elements are used to achieve full color spectrum, then color completeness is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent merges multiple functions into a single light emitting element structure that simultaneously emits blue and green light, with fluoride-based phosphors converting portions to red light. This integration achieves complete color spectrum (NTSC >100%, DCI-P3 >95%) while reducing device complexity by eliminating the need for separate red, green, and blue LED chips
Solution Approach 2:
The light emitting element serves multiple functions: direct blue and green light emission, and serving as an excitation source for phosphor-based red light generation. The fluoride-based phosphors similarly provide both wavelength conversion and structural stability, achieving universal functionality with reduced component count
3Reliability
If phosphors are exposed without protective coating, then manufacturing simplicity is maintained, but reliability and moisture resistance deteriorate
Solution Approach 1:
The patent applies thin film protective coatings including organic layers (epoxy resin 5-20μm, silicone resin 3-10μm) and inorganic layers (SiO2 2-10μm, Si3N4 3-15μm) that flexibly encapsulate the phosphors. These thin films provide effective moisture barrier protection while maintaining manufacturing feasibility and not significantly increasing device complexity
Solution Approach 2:
The organic and inorganic coating layers serve as intermediary protective barriers between the phosphors and the external environment. These intermediate layers prevent direct contact with moisture and oxygen, significantly improving reliability while the gradual layering approach maintains manufacturing simplicity
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 solution achieves high color purity with narrow full width at half maximum (FWHM) for red light and improved reliability by minimizing the number of light emitting elements, resulting in enhanced light emitting efficiency and color characteristics for display applications.
Implementation Method 1
a wavelength conversion part wavelength-converting a portion of light emitted from the light emitting element into red light, and including fluoride-based phosphors
Implementation Method 2
organic or inorganic coating layers enclosing the fluoride-based phosphors
Implementation Method 3
a protective layer disposed on at least one surface of the wavelength conversion part and performing moisture-proofing functions
Data Source
AI summary
A light emitting device includes: a substrate; a light emitting element mounted on the substrate and emitting blue light and green light; and a wavelength conversion part wavelength-converting a portion of light emitted from the light emitting element into red light, and including fluoride-based phosphors represented by Chemical Formula: AxMFy:Mn4+ (2≦x≦3 and 4≦y≦7, where element A is at least one selected from a group consisting of Li, Na, K, Rb, and Cs and element M is at least one selected from a group consisting of Si, Ti, Zr, Hf, Ge and Sn) and organic or inorganic coating layers enclosing the fluoride-based phosphors.