Quantum Dot Layer Uniformity via Cryogenic Sublimation
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Solution Overview
Problem
The 'coffee ring' effect in thermal evaporation processes for manufacturing quantum dot layers results in non-uniform thickness, affecting image display quality and service life in display panels.
Innovation Solution
A method involving forming a layer solution on a substrate, solidifying it by lowering the temperature, and removing the solvent via sublimation in a vacuum, eliminating the 'coffee ring' effect and achieving uniform thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If thermal evaporation process is used to remove solvent from layer solution, then the solvent is converted from liquid into gas, but the formed layers are non-uniform due to the 'coffee ring' effect
Solution Approach 1:
The patent utilizes phase transitions of the solvent through three distinct stages: freezing (liquid to solid), sublimation (solid to gas), and vacuum drying. By controlling the temperature to freeze the solvent first, then applying vacuum to enable sublimation, the method eliminates capillary flow that causes the coffee ring effect, achieving uniform layer thickness while efficiently removing the solvent
Solution Approach 2:
The patent employs a vacuum environment (inert atmosphere with reduced pressure) during the sublimation process. This vacuum condition prevents oxidation and other chemical reactions, while also facilitating the sublimation of frozen solvent. The inert environment ensures that the quantum dot particles remain stable and the layer structure maintains uniformity during solvent removal
2Ease of manufacture
If traditional thermal evaporation is used to dry the layer solution, then the solvent is removed, but the layers become thin in the middle and thick on both sides
Solution Approach 1:
The patent applies preliminary freezing action before solvent removal. By freezing the layer solution first, the solvent is locked in place as ice, preventing the capillary flow that causes non-uniform distribution during evaporation. This preliminary solidification step ensures that subsequent sublimation removes solvent uniformly from the entire layer without creating the coffee ring effect
Solution Approach 2:
The patent replaces the thermal evaporation mechanism with a cryogenic sublimation mechanism. Instead of heating to evaporate solvent (which causes uneven flow), the method uses freezing followed by vacuum sublimation. This substitution of the physical mechanism fundamentally eliminates the coffee ring effect while maintaining ease of manufacture through controlled phase transitions
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 method ensures uniform thickness of quantum dot layers, enhancing image display quality and service life by reducing the 'coffee ring' effect and improving production efficiency.
Implementation Method 1
solidifying the layer solution by lowering the temperature of the layer solution
Implementation Method 2
forming the layer structure by removing a solvent in the solidified layer solution via a sublimation process
Data Source
AI summary
A layer structure, a manufacturing method thereof, a display substrate, a backlight and a display device are provided. The manufacturing method includes forming a layer solution on a substrate (21); solidifying the layer solution by lowering the temperature of the layer solution; and forming the layer structure by removing a solvent in the solidified layer solution via a sublimation process.