Quantum Dot Ink Viscosity Control via Phase Separation
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Solution Overview
Problem
The development of quantum dot ink suitable for ink-jet printing in quantum dot light emitting diode (QLED) displays is hindered by the difficulty in achieving high viscosity and appropriate surface tension, which affects the printing process and the formation of a stable quantum dot layer.
Innovation Solution
A quantum dot ink is formulated using a non-polar organic solvent, a surface tension modifier, and a hydrophobic quantum dot, with phase separation between the quantum dot and carrier transport material, achieving a viscosity of 10 cP to 12 cP and surface tension of 32 dynes/cm to 42 dynes/cm, allowing for effective ink-jet printing and the formation of a two-layer structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If quantum dot is dispersed in organic solvent to form quantum dot ink, then the ink can be used for ink-jet printing, but the viscosity is too low and surface tension is inappropriate, causing printing difficulties
Solution Approach 1:
The patent modifies the physical and chemical parameters of the quantum dot ink by introducing a carrier transport material that undergoes phase separation with the quantum dot. This phase separation fundamentally changes the ink's viscosity and surface tension characteristics, enabling it to meet the requirements for high-quality ink-jet printing while maintaining quantum dot dispersion stability.
Solution Approach 2:
The patent creates a composite ink system comprising quantum dots, carrier transport material, and organic solvent. The carrier transport material and quantum dot form a phase-separated composite structure, where the carrier transport material provides appropriate viscosity and surface tension properties, while the quantum dot maintains its functional characteristics for light emission.
2Device complexity
If quantum dot ink is formulated for ink-jet printing, then printing process is simplified, but achieving appropriate viscosity and surface tension is difficult
Solution Approach 1:
The patent combines multiple functions into the carrier transport material: it serves as both the dispersion medium for quantum dots and the phase-separated component that provides appropriate viscosity and surface tension. This merging of functions simplifies the overall ink formulation process while achieving the required rheological properties for ink-jet printing.
Solution Approach 2:
The patent utilizes phase separation between the carrier transport material and quantum dot to achieve the desired ink properties. The phase transition from a homogeneous mixture to a phase-separated structure naturally adjusts the viscosity and surface tension to appropriate ranges for ink-jet printing, eliminating the need for complex formulation adjustments.
3Productivity
If quantum dot ink is printed, then quantum dot layer is formed, but flow issues and blockages occur due to inappropriate viscosity and surface tension
Solution Approach 1:
The patent precisely controls the viscosity and surface tension parameters through phase separation, ensuring they fall within the optimal range for ink-jet printing. This parameter optimization prevents flow issues and blockages during printing, ensuring reliable and consistent quantum dot layer formation across multiple printing operations.
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 solution enables the successful manufacturing of quantum dot light emitting devices through ink-jet printing, simplifying the process and reducing costs by ensuring the appropriate viscosity and surface tension for ink-jet printing, while preventing flow issues and blockages.
Implementation Method 1
a surface tension modifier and a hydrophobic quantum dot, the quantum dot ink further includes a carrier transport material... the surface tension of the quantum dot ink is from 32 dynes/cm to 42 dynes/cm
Implementation Method 2
phase separation is present between the hydrophobic quantum dot and the carrier transport material
Implementation Method 3
the viscosity of the quantum dot ink is from 10 cP to 12 cP
Data Source
AI summary
A quantum dot ink, a manufacturing method thereof and a quantum dot light emitting diode device are provided. The quantum dot ink includes a non-polar organic solvent, a surface tension modifier and a hydrophobic quantum dot, the quantum dot ink further includes a carrier transport material, wherein phase separation is present between the hydrophobic quantum dot and the carrier transport material. After completing ink-jet printing the quantum dot ink, phase separation occurs between the hydrophobic quantum dot and the carrier transport material. Thus, the two-layer structure of a hydrophobic quantum dot layer and a carrier transport material layer is formed through one process. Not only a quantum dot light emitting device is manufactured by the method of ink-jet printing, but also the operation is simplified, and the manufacturing cost of the quantum dot light emitting device is reduced.