Quantum Dot Display Substrate for Coffee Ring Suppression
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Solution Overview
Problem
Ink-jet printed quantum dot layers in display devices often suffer from the 'coffee ring effect', resulting in uneven thickness and reduced efficiency and lifetime due to solvent volatilization differences causing quantum dots to concentrate more at the edges than the center of pixel openings.
Innovation Solution
A method involving ink-jet printing of a curable ink containing quantum dots and photocurable monomers, where the peripheral region is irradiated to polymerize monomers, increasing viscosity and preventing liquid flow to the edges, thus avoiding the coffee ring effect and achieving uniform quantum dot layer thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ink-jet printing is used to deposit quantum dot layers, then the manufacturing process is simplified and productivity is improved, but the coffee ring effect causes uneven thickness and reduces manufacturing precision
Solution Approach 1:
The patent applies preliminary action by performing partial polymerization of photocurable monomers in the peripheral region before complete drying occurs. This pre-established viscosity gradient prevents the coffee ring effect from developing, ensuring uniform quantum dot distribution while maintaining the efficiency of ink-jet printing deposition
2Ease of manufacture
If solvent volatilization is allowed to proceed naturally, then the drying process is simple, but quantum dots concentrate at edges forming the coffee ring effect and reducing reliability
Solution Approach 1:
The patent changes the physical parameter of viscosity dynamically during the drying process. By inducing partial polymerization in the peripheral region, the viscosity increases locally to create a viscosity gradient that counteracts solvent flow toward edges, preventing quantum dot aggregation and improving device reliability
Solution Approach 2:
The photocurable monomers act as an intermediary substance that mediates between the solvent and quantum dots. Through controlled polymerization, they modify the fluid dynamics of the ink droplet, preventing harmful coffee ring formation while maintaining ease of manufacturing
3Device complexity
If quantum dots are allowed to distribute naturally during drying, then no additional processing is needed, but uneven distribution occurs with higher concentration at edges reducing device performance
Solution Approach 1:
The patent changes the chemical state of photocurable monomers from unpolymerized to partially polymerized in the peripheral region. This parameter change creates a viscosity gradient that actively controls quantum dot distribution, achieving uniform thickness without adding complex processing steps
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 ensures a quantum dot layer with uniform thickness, enhancing the efficiency and lifetime of display devices by inhibiting the coffee ring effect and maintaining even quantum dot distribution across pixel openings.
Implementation Method 1
the peripheral region is irradiated to polymerize monomers
Implementation Method 2
increasing viscosity and preventing liquid flow to the edges
Data Source
AI summary
A display substrate, a display panel and a method for manufacturing the display substrate are provided. The display substrate comprises a backing substrate and a plurality of pixel areas formed on the backing substrate, wherein the display substrate further comprises a quantum dot layer, the quantum dot layer comprises a plurality of quantum dot units located in the plurality of pixel areas respectively, wherein the quantum dot units comprise a matrix layer and quantum dots dispersed in the matrix layer, the matrix layer comprises a central region and a peripheral region disposed around the central region, the peripheral region comprises a polymer of photocurable monomers, and the central region comprises unpolymerized photocurable monomers.