High rate printing of microscale and nanoscale patterns using interfacial convective assembly
Interfacial convective assembly can assemble any type of nanoparticles or other nanoelements in minutes to form microscale and nanoscale patterns in vias or trenches in patterned substrates. A solvent film is deposited on a patterned substrate. An aqueous suspension of nanoparticles is deposited onto the solvent film, thereby forming an interfacial liquid system comprising the nanoparticles within an enclosed space on the substrate. The substrate is then heated, thereby inducing convective flow in the interfacial liquid system. The convective flow includes solutal Marangoni convective flow in a direction towards the patterned substrate, causing nanoelements to be transferred to and bind to the patterned substrate. The nanoelements can be assembled on both hydrophilic and hydrophobic surfaces. Nanoparticles can fuse during the process to provide solid or single crystalline electrical circuit components.
1. A method of interfacial convective assembly of nanoelements, the method comprising the steps of:
(a) providing a patterned substrate and a suspension of nanoelements in a binary solvent system, the binary solvent system comprising a first component and a second component, wherein the first component has a higher volatility and a lower surface tension than the second component;
(b) depositing the suspension on the substrate;
(c) confining the suspension, or a portion thereof, within an enclosed space on the substrate;
(e) heating the substrate, thereby inducing convective flow in the binary solvent system, wherein the convective flow comprises solutal Marangoni convective flow in a direction towards the patterned substrate, and wherein the solutal Marangoni convective flow induces a total convective flow of at least about 1 m·s −1 ;
whereby nanoelements of the suspension are transferred to and bind to one or more areas of the patterned substrate.
2. The method of claim 1 , wherein the first component of the binary solvent system comprises one or more of acetaldehyde, acetic acid, acetone, acetonitrile, butanol, ethanol, ethylene glycol, 1-propanol, isopropanol, methanol, n-butyl acetate, pyridine, hydrazine, and tetrahydrofuran, and wherein the second component of the binary solvent system is water.
3. The method of claim 1 , wherein the one or more areas of the patterned substrate onto which nanoelements are transferred have a contact angle from 0° to about 130°.
4. The method of claim 1 , wherein the one or more areas of the patterned substrate onto which nanoelements are transferred have substantially the same contact angle as areas of the patterned substrate that do not bind nanoelements.
5. The method of claim 1 , wherein the one or more areas of the patterned substrate onto which nanoelements are transferred have a lower contact angle than areas of the patterned substrate that do not bind nanoelements.
6. The method of claim 1 , wherein the one or more areas of the patterned substrate onto which nanoelements are transferred are sunken below areas of the patterned substrate that do not bind nanoelements, and wherein the difference in height between the areas that do and do not bind nanoelements is at least about the same as the size of the nanoelements.
7. The method of claim 6 , wherein nanoelements are deposited into vias or trenches of the patterned substrate.
8. The method of claim 1 , wherein the patterned substrate has at least one pattern feature having a dimension in the range from about 1 nm to about 1000 nm.
9. The method of claim 8 , wherein the patterned substrate has at least one pattern feature having a dimension in the range from about 5 nm to about 100 nm.
10. The method of claim 1 , wherein the binary solvent system is formed by drop casting an aqueous suspension of said nanoelements onto a film comprising the first component of the binary solvent system.
11. The method of claim 1 , wherein confining the suspension comprises placing a cover over the suspension.
12. The method of claim 1 , further comprising
(e) tilting the patterned substrate, whereby non-transferred nanoelements are removed from the patterned substrate.
13. The method of claim 1 , wherein the patterned substrate is heated in (d) to a temperature in the range from about 40° C. to about 75° C.
14. The method of claim 1 , wherein the method is completed in less than 10 minutes.
15. The method of claim 1 , wherein a patterned monolayer of the nanoelements is deposited onto the substrate.
16. The method of claim 1 , wherein the nanoelements are nanoparticles comprising gold, silver, one or more polymers, carbon, silica, or a combination thereof.
17. The method of claim 16 , wherein at least a portion of the transferred nanoparticles fuse together to form a fused nanoparticle structure.
18. The method of claim 1 , wherein the method does not include electrophoretic or dielectrophoretic assembly of the nanoelements.
19. A method of fabricating a patterned multilayered nanomaterial, the method comprising performing the method of claim 1 to assemble a first patterned monolayer of nanoelements followed by repeating the method one or more times to add additional monolayers of the nanoelements on top of the previous monolayer or layers.