Perovskite Nanocrystal Color Conversion for Display Gamut
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Solution Overview
Problem
Conventional display technologies, such as LCDs, have a limited color gamut due to reliance on color filters that cannot produce highly saturated colors, as they are restricted by the primary red, blue, and green wavelengths of the light source.
Innovation Solution
A display device incorporating a light emitter and a color conversion layer with luminescent crystals of perovskite structure, specifically cesium lead halide nanocrystals, that convert blue light into red and green light, allowing for a broader color spectrum and improved color accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If color filters are used to achieve broad color spectrum, then color gamut is improved, but color saturation is limited due to restriction by primary wavelengths of light source
Solution Approach 1:
The patent changes the fundamental parameter of color generation from filtering (subtractive method) to wavelength conversion (additive method). By using luminescent crystals with specific emission wavelengths that can be precisely controlled through crystal composition and size, the system achieves both broad color gamut and high color saturation independently of the light source spectrum.
Solution Approach 2:
The patent employs composite structures combining light emitters with luminescent crystal layers. These composite materials enable the conversion of blue light into precise red and green wavelengths, achieving superior color accuracy and saturation that cannot be obtained with conventional color filters alone.
2Device complexity
If conventional color filters are used, then device structure is simple, but color accuracy and saturation cannot exceed the light source spectrum
Solution Approach 1:
The invention changes the operational principle from passive filtering to active wavelength conversion. The luminescent crystals are engineered with specific bandgap energies that determine their emission wavelengths, allowing precise control over output colors independent of the input light source spectrum.
Solution Approach 2:
The luminescent crystals act as intermediaries between the blue light source and the final displayed colors. These crystals absorb blue photons and re-emit at precise red and green wavelengths, serving as a mediating layer that decouples the light source characteristics from the display color accuracy.
3Measurement precision
If luminescent crystals are used for wavelength conversion, then color saturation and gamut are improved, but material stability and RoHS compliance become concerns
Solution Approach 1:
The patent uses composite perovskite structures (e.g., CsPbBr3, CsPbI3) that combine organic and inorganic components. These composite materials offer both the desired optical properties for high-color-purity emission and improved stability compared to purely inorganic quantum dots, while enabling RoHS compliance through careful material selection.
Solution Approach 2:
The patent applies different perovskite compositions and protective shell materials at different locations within the conversion layer to optimize both color performance and stability. By tailoring the local material properties, the system achieves high color saturation in specific wavelength regions while maintaining overall structural stability and environmental compliance.
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 enables the display device to achieve superior color accuracy and efficiency by converting blue light into red and green light with high quantum yield and narrow spectral distribution, exceeding 90% light conversion efficiency and compliance with RoHS directives, while reducing material usage and maintaining high stability.
Implementation Method 1
at least one of the conversion layer portions of the set is configured to emit light of a wavelength in response to an excitation with light emitted by at least one corresponding light emitter portion of the set. The at least one light emitter portion of the set is configured to emit light with an excitation wavelength. This emitted light excites luminescent crystals in the at least one color conversion layer which in response to the excitation emit light of a wavelength different to the shorter excitation wavelength
Data Source
AI summary
A display device includes a light emitter comprising a set of light emitter portions, wherein at least one light emitter portion of the set is configured to emit light with an excitation wavelength, and a color conversion layer including a set of conversion layer portions. At least one conversion layer portion of the set comprises a film comprising a solid polymer composition that includes luminescent crystals of perovskite structure, which are selected from compounds of formula (I): M1aM2bXc (I), wherein M1 represents Cs, M2 represents Pb, and X independently represents anions selected from the group consisting of Cl, Br, I, cyanide, and thiocyanate. The luminescent crystals are of size between 3 nm and 3000 nm, and emit light of a wavelength in response to excitation by the light emitted by at least one corresponding light emitter portion of the set, wherein the excitation wavelength is shorter than the wavelength.