Layered Material Inks with Controlled Flake Thickness Distribution
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Solution Overview
Problem
Existing methods for manufacturing printable conductive inks, such as those based on graphene, often result in inks with unsatisfactory thickness distribution and optical characteristics, leading to incomplete printing or damage to printing apparatus, and fail to consider the specific requirements of different printing processes.
Innovation Solution
The development of an ink with a controlled thickness distribution of layered material flakes, including at least 20% single-layer flakes, and the use of ultracentrifugation and filtration to achieve a suitable flake size and concentration for optimal printing, along with the addition of modifiers to adjust surface energy and viscosity for specific printing techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods are used to manufacture printable conductive inks, then production can be achieved, but the thickness distribution is unsatisfactory and optical characteristics are poor
Solution Approach 1:
The patent applies preliminary action by performing ultracentrifugation and filtration on the layered material flakes before ink formulation. This pre-processing step controls the flake size distribution and removes excessive thick flakes that would cause printing defects, thereby achieving satisfactory thickness distribution without complicating the actual printing process
Solution Approach 2:
The patent employs parameter changes by adjusting the ultracentrifugation speed, time, and filtration parameters to optimize the flake size distribution. By carefully controlling these parameters, the ink achieves the desired thickness distribution (including at least 20% single-layer flakes) while maintaining ease of manufacture through standardized processing conditions
2Illumination intensity
If conventional ink formulations are used, then printing can proceed, but optical transmittance is insufficient for display applications
Solution Approach 1:
The patent applies local quality by ensuring that the ink formulation provides optimal optical transmittance specifically in the printed layer region. By controlling the flake size distribution and concentration, the ink achieves at least 80% optical transmittance in the printed area while maintaining reliable printing quality through consistent flake deposition
Solution Approach 2:
The patent uses composite materials by formulating an ink that combines layered material flakes with specific carriers and modifiers. This composite formulation optimizes both optical transmittance and printing reliability, as the carrier and modifiers work together with the flakes to achieve the desired performance characteristics
3Reliability
If thick flakes are present in the ink, then conductivity can be achieved, but printing apparatus may be damaged or printing may be incomplete
Solution Approach 1:
The patent applies the taking out principle by using ultracentrifugation and filtration to extract and remove thick flakes from the ink formulation. This ensures that only appropriately sized flakes remain, maintaining electrical conductivity while preventing damage to printing apparatus and ensuring complete printing
Solution Approach 2:
The patent uses an intermediary approach by introducing carriers and modifiers as mediating substances between the layered material flakes and the printing apparatus. These intermediaries help control flake distribution and prevent aggregation, ensuring reliable conductivity without causing mechanical issues during printing
4Illumination intensity
If single-layer flakes are increased to improve optical properties, then transmittance improves, but conductivity may be reduced
Solution Approach 1:
The patent applies parameter changes by optimizing the concentration and size distribution of single-layer flakes in the ink. By carefully controlling these parameters, the formulation achieves at least 80% optical transmittance while maintaining sufficient electrical conductivity through appropriate flake density and arrangement
Solution Approach 2:
The patent uses composite materials to balance optical and electrical properties. The ink formulation combines single-layer flakes with carriers and modifiers that work synergistically to maintain both high optical transmittance and adequate electrical conductivity, achieving a balance that satisfies both requirements
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 resulting printed layers exhibit improved conductivity and optical transmittance, with a sheet resistance of not more than 10^3 kΩ/square and optical transmittance of at least 80%, suitable for flexible electronics and display applications, while being flexible and resistant to bending.
Implementation Method 1
The dispersion is subjected to ultracentrifugation to provide a thickness distribution of the flakes in the second population corresponding to any range identified with respect to the first aspect
Implementation Method 2
The dispersion is filtered to remove particles with a lateral size greater than a predetermined value
Implementation Method 3
Graphite can be exfoliated by chemical wet dispersion followed by ultrasonication, both in aqueous and nonaqueous solvents
Data Source
Figure 1
Figure 2a~2f
Figure 3a~3g
AI summary
An ink disclosed herein comprises a carrier liquid with a dispersion of flakes derived from a layered material. The thickness of each flake depends on the number of layers of the layered material in the flake. The thickness distribution of the flakes includes: at least 20% by number of single layer flakes; at least 40% by number cumulatively of single, double and triple layer flakes; or not more than 40% by number of flakes having ten or more layers. The layered material is selected from one or more of elemental materials such as graphene (typically derived from pristine graphite), metals (e.g., NiTe2, VSe2), semi-metals (e.g., WTa2, TcS2), semiconductors (e.g., WS2, WSe2, MoS2, MoTe2, TaS2, RhTe2, PdTe2), insulators (e.g., h-BN, HfS2), superconductors (e.g., NbS2, NbSe2, NbTe2, TaSe2) and topological insulators and thermo-electrics (e.g., Bi2Se3, Bi2Te3). Also disclosed are methods of manufacturing suitable inks and uses of the inks.