Wavelength Conversion Member Bubble Defect Reduction
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Solution Overview
Problem
The existing wavelength conversion members using quantum dots in liquid crystal display devices face challenges with oxygen barrier properties, as the emission intensity of quantum dots decreases due to photooxidation, and the use of polymerizable compounds with molecular weights below 200 can lead to bubble formation, affecting the integrity and oxygen barrier performance of the wavelength conversion layer.
Innovation Solution
A wavelength conversion member is developed with a cured layer formed using a polymerizable composition containing quantum dots and a polymerizable compound with a molecular weight of 200 or lower, where the number of bubble-shaped defects is minimized, and the oxygen barrier properties are enhanced by using substrates with low oxygen permeability and specific curing conditions, such as controlled temperature and inert gas environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polymerizable compound with molecular weight of 200 or lower is used to improve oxygen barrier properties, then oxygen barrier properties are improved, but bubbles are formed in the wavelength conversion layer
Solution Approach 1:
The patent changes the molecular weight parameter of the polymerizable compound to 200 or lower to improve oxygen barrier properties. This parameter change enables the formation of a denser polymer matrix that better prevents oxygen penetration, directly addressing the reliability issue while accepting the trade-off of bubble formation during curing.
2Reliability
If quantum dots are protected from oxygen to prevent photooxidation, then emission intensity is maintained, but the structure becomes more complex
Solution Approach 1:
The patent creates a composite material system where quantum dots are embedded in a polymer matrix formed from low molecular weight polymerizable compounds. This composite structure provides oxygen barrier protection to the quantum dots, maintaining emission intensity while integrating the protection function within the wavelength conversion layer itself rather than adding separate protective layers.
Solution Approach 2:
The patent creates an inert environment within the polymer matrix that surrounds and protects quantum dots from oxygen exposure. The cured polymer network forms an oxygen-impermeable barrier that prevents oxygen from reaching the quantum dots, thereby preventing photooxidation and maintaining emission intensity without requiring external inert gas environments.
3Reliability
If the wavelength conversion layer is cured completely to improve oxygen barrier properties, then oxygen barrier properties are improved, but peeling may occur due to internal stress
Solution Approach 1:
The patent uses polymerizable compounds with molecular weight of 200 or lower, which when cured, create a polymer matrix with specific mechanical properties that balance oxygen barrier performance and adhesion. The low molecular weight enables dense packing for oxygen barrier while the resulting polymer structure manages curing stress to prevent peeling.
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 effectively suppresses bubble formation and improves oxygen barrier properties, preventing peeling and deterioration, thereby maintaining the integrity and performance of the wavelength conversion layer in liquid crystal display devices.
Implementation Method 1
a wavelength conversion layer disposed between the first substrate and the second substrate and including quantum dots which are excited by excitation light to emit fluorescence
Implementation Method 2
the wavelength conversion layer is a cured layer obtained by curing a polymerizable composition which includes the quantum dots and a polymerizable compound having a molecular weight of 200 or lower
Data Source
AI summary
The wavelength conversion member includes: a first substrate; a second substrate; and a wavelength conversion layer disposed between the first substrate and the second substrate and including quantum dots which are excited by excitation light to emit fluorescence. The wavelength conversion layer is a cured layer obtained by curing a polymerizable composition which includes the quantum dots and a polymerizable compound having a molecular weight of 200 or lower, and the number of bubble-shaped defects having a diameter of 0.1 mm or more in the wavelength conversion layer is less than 10 per 100 cm2.