Carbon Quantum Dot Micro-LED Color Conversion for Stable Red Emission
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Solution Overview
Problem
Existing micro-LED technologies face challenges in developing cost-effective color conversion with enhanced light emission efficiency and minimized excitation light leakage, particularly in producing red-color carbon quantum dots that are inefficiently excited by short wavelengths like blue and UV light, have low quantum yield, and exhibit excitation wavelength-dependent emission color.
Innovation Solution
A solvothermal synthesis method is used to produce carbon quantum dots from a mixture of 3,4-dihydroxy-L-phenylalanine (LDOPA) and urea in dimethylformamide, which are then purified and applied in a micro-LED display, utilizing nitrogen-doped graphene particles to achieve red emission with a quantum yield greater than 30% and a large Stoke's shift, allowing efficient excitation across 390-450 nm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional carbon quantum dots are used for color conversion in micro-LED, then the structure is simple, but the light emission efficiency is low and excitation light leakage is high
Solution Approach 1:
The patent employs a composite color conversion layer comprising multiple materials including carbon quantum dots, organic dyes, and polymer matrices. This composite structure enables efficient light emission by combining the advantages of different materials while minimizing excitation light leakage through optimized material selection and layer configuration.
Solution Approach 2:
The invention implements spatially varying properties within the color conversion layer by positioning different materials at specific locations and depths. The carbon quantum dots are strategically placed to absorb excitation light, while organic dyes are positioned to emit at desired wavelengths, creating localized functional zones that optimize overall light emission efficiency.
2Reliability
If red-color carbon quantum dots are synthesized for micro-LED display, then the emission color is achieved, but the quantum yield is low and excitation wavelength dependence is high
Solution Approach 1:
The patent merges carbon quantum dots with organic dye molecules to create a hybrid color conversion system. This combination allows the carbon quantum dots to provide stable excitation absorption across multiple wavelengths while the organic dyes contribute high quantum yield red emission, thereby achieving both reliability and adaptability simultaneously.
Solution Approach 2:
The invention optimizes the physical and chemical parameters of the carbon quantum dots including size distribution, surface functionalization, and doping composition. By controlling these parameters during synthesis, the system achieves enhanced quantum yield and reduced excitation wavelength dependence, enabling reliable red emission across a broad spectral range.
3Ease of manufacture
If carbon quantum dots are used to minimize excitation light leakage, then light emission efficiency improves, but the manufacturing complexity increases
Solution Approach 1:
The patent incorporates carbon quantum dots and other color conversion materials directly into the micro-LED fabrication process during the chip manufacturing stage. This preliminary integration eliminates the need for separate post-fabrication coating steps, thereby reducing overall manufacturing complexity while maintaining the light emission efficiency benefits of the carbon quantum dot structure.
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 method enables red emission carbon quantum dots with stable excitation across UV and blue wavelengths, achieving high quantum yield and consistent emission spectra, suitable for micro-LED displays and other applications.
Implementation Method 1
carbon quantum dots... achieving high quantum yield and consistent emission spectra, suitable for micro-LED displays... efficient excitation across 390-450 nm
Implementation Method 2
A solvothermal synthesis method is used to produce carbon quantum dots from a mixture of 3,4-dihydroxy-L-phenylalanine (LDOPA) and urea in dimethylformamide
Implementation Method 3
achieving high quantum yield and consistent emission spectra... with a large Stoke's shift, allowing efficient excitation across 390-450 nm
Data Source
AI summary
Disclosed herein are materials and a micro-LED display with carbon-based light-emitting materials, carbon quantum dots, that are made by a solvothermal synthesis of a mixture of aromatic amino acid, 3,4-dihydroxy-L-phenylalanine (LDOPA), and urea in dimethylformamide (DMF). The mixture is heated in a sealed pressure reactor at a temperature, ranging from 120 degrees Celsius to 350 degrees Celsius, for 4-24 hours. The product is then purified to collect the solid powder. The purified CDs can be dissolved in an acrylate monomer solution or a polymer solution for material delivery and curing process on a target substrate for the applications, including light-emitting devices or sensors.