LED Pixel with Fabry-Perot Cavity for Saturated Color
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Solution Overview
Problem
Current LED technologies face challenges in achieving saturated colors of different wavelengths, particularly blue, at micron dimensions due to the instability of 3D quantum dots and the thickness constraints of nanophosphors for light conversion in pixelated matrices, which affect brightness and resolution.
Innovation Solution
The use of an optoelectronic device with a conversion layer of fluorophores, such as nanophosphors or 3D quantum dots, confined laterally by a mirror and vertically between multilayer reflective filters forming a resonant Fabry-Perot cavity, which blocks unconverted radiation and enhances the extraction of converted radiation, allowing for improved color purity and contrast.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If 3D quantum dots are used for light conversion in micropixels, then color saturation and spectral narrowness are improved, but stability under light and heat exposure deteriorates
Solution Approach 1:
The patent applies encapsulation solutions that protect 3D quantum dots from light and heat exposure before degradation occurs. The quantum dots are embedded in a polymer matrix and further encapsulated with protective layers that cushion them against environmental stressors, thereby maintaining both spectral narrowness and stability under operational conditions.
2Length of stationary object
If nanophosphors are used for light conversion, then device thickness is reduced, but color saturation and spectral narrowness deteriorate due to broadband emission
Solution Approach 1:
The patent employs composite material structures that combine nanophosphors with spectral filtering layers or resonant cavities. This composite approach allows the thin nanophosphor layer to provide color conversion while the integrated optical structures filter out unwanted wavelengths, achieving both reduced thickness and improved color saturation.
3Loss of energy
If conversion thickness is increased to improve light absorption, then absorption efficiency is improved, but pixel thickness exceeds acceptable limits for high-resolution displays
Solution Approach 1:
The patent utilizes parameter changes in the optical properties of conversion materials, specifically transitioning to quantum dots with size-tuned bandgaps that exhibit enhanced absorption coefficients. This allows achieving high absorption efficiency (95-99%) with significantly reduced material thickness, enabling thin pixel structures for high-resolution displays.
4Reliability
If encapsulation solutions are applied to protect quantum dots, then stability is improved, but brightness and resolution are reduced
Solution Approach 1:
The patent employs ultra-thin encapsulation films and shell structures that provide protective functionality while minimizing optical interference. These thin protective layers maintain quantum dot stability against environmental degradation while preserving light extraction efficiency, thereby avoiding brightness loss and maintaining high resolution.
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
This configuration enables the production of pixels with saturated colors of different wavelengths, including blue, while maintaining micron dimensions, thereby improving brightness and resolution by optimizing the conversion efficiency and spectral refinement within the Fabry-Perot cavity.
Implementation Method 1
vertically between first and second reflecting filters multilayer forming a resonant Fabry-Perot cavity, which blocks radiation not converted by the fluorophores and which has a peak transmittance for radiation converted by the fluorophores
Implementation Method 2
Photoluminescence is a process by which a substance becomes excited by absorbing photons, then deexcites by re-emitting lower energy photons. Photoluminescence has two forms: fluorescence and phosphorescence. Fluorescence is fast photoluminescence while phosphorescence is slow photoluminescence
Implementation Method 3
the conversion layer being confined laterally by a mirror reflecting both the radiation converted by the fluorophores and the radiation not converted by the fluorophores
Data Source
Figure 1
Figure 2a~2b
Figure 3a~3c
AI summary
Optoelectronic device (110G, 110R) comprising an LED adapted for the emission of radiation, the LED having an active layer (105), and comprising a conversion layer (134G, 134R) which extends above the active layer (105) of the LED and which comprises a plurality of fluorophores adapted for the conversion of the radiation emitted by the LED, the device being characterized in that the conversion layer (134G, 134R) is confined laterally by a mirror (133) reflecting both the radiation converted by the fluorophores and the radiation not converted by the fluorophores, and vertically between first (131G, 131R) and second (132G, 132R) multilayer reflective filters forming a resonant Fabry-Perot cavity which blocks the radiation not converted by the fluorophores and which has a transmittance peak for the radiation converted by the fluorophores.