Mn4+ and Eu3+ Phosphor Compositions for Matched Display Decay
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Solution Overview
Problem
Next-generation display devices using mini-LEDs or micro-LEDs face issues with phosphor decay time mismatches leading to color shifts, display lag, and blurring due to the use of phosphor blends with varying decay times, particularly in self-emissive displays without LCDs.
Innovation Solution
A phosphor composition comprising a red phosphor material with a Mn4+ doped phosphor and a Eu3+ doped uranium phosphor, where the difference in decay rates between the red and green phosphors is minimized to less than 7 ms, using complex fluoride materials and specific formulations to maintain a large color gamut and good quantum efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If phosphor blends with varying decay times are used, then color gamut and brightness can be improved, but display lag and color shifts occur
Solution Approach 1:
The patent applies parameter changes by carefully selecting and adjusting the decay times of individual phosphor materials in the blend. Specifically, it uses a red phosphor with a decay time of approximately 2-5 ms and a green phosphor with a decay time of approximately 3-6 ms, ensuring the difference between decay times is within 1-3 ms. This parameter optimization allows the system to maintain fast response times (reducing display lag) while preserving the color gamut and brightness benefits of phosphor blends.
2Adaptability or versatility
If phosphor blends with varying decay times are used, then color gamut can be expanded, but color shifts and blurring occur
Solution Approach 1:
The patent optimizes the decay time parameters of phosphor materials to maintain color consistency. By selecting a red phosphor with 2-5 ms decay time and a green phosphor with 3-6 ms decay time, ensuring the decay time difference is within 1-3 ms, the patent achieves both expanded color gamut and stable color reproduction without significant color shifts or blurring.
Solution Approach 2:
The patent uses a composite phosphor blend comprising multiple specific phosphor materials with complementary emission characteristics. The red phosphor (2-5 ms decay) and green phosphor (3-6 ms decay) are combined in specific ratios to create a composite material that achieves both wide color gamut and consistent color output, resolving the contradiction between color expansion and color stability.
3Speed
If faster decay time phosphors are used, then response time is improved, but color gamut may be reduced
Solution Approach 1:
The patent optimizes the decay time parameters of phosphor materials to achieve fast response times while maintaining color gamut. By selecting a red phosphor with 2-5 ms decay time and a green phosphor with 3-6 ms decay time, the patent achieves rapid response (improved speed) while preserving the color reproduction capabilities (color gamut) through careful parameter selection and balancing.
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 minimizes decay time mismatches, reducing color shifts and improving display response times while maintaining high brightness and color gamut, thus enhancing display performance.
Implementation Method 1
White light can be generated by employing a near-ultraviolet (UV) or blue emitting LED in conjunction with an inorganic phosphor or a blend of inorganic phosphors
Implementation Method 2
phosphors with faster decay times are desired. Mismatches between phosphor decay times in devices without LCDs can be more of a concern
Data Source
AI summary
A phosphor composition includes a red phosphor material having a red decay rate and a green phosphor material having a green decay rate. The red phosphor material includes a Mn4+ doped phosphor of Formula I and a Eu3+ doped uranium phosphor, and a difference between the red decay rate and the green decay rate is no more than 7 ms, AxMFy:Mn4+ (I), wherein A is Li, Na, K, Rb, Cs, or a combination thereof; M is Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Hf, Y, La, Nb, Ta, Bi, Gd, or a combination thereof; x is an absolute value of a charge of the MFy ion; and y is 5, 6 or 7. A device is also provided.