Method for providing an aggregate of aligned nanowires

Abstract

A method for forming an aggregate of assembled aligned nanowires, wherein said nanowires comprise an elongate wire portion and a head portion at a first end of the elongate wire portion, comprising providing a fluid comprising a first liquid, a second liquid and a plurality of nanowires, wherein the first and second liquids phase separate into a first phase, a second phase, and an interface between the first and second phases; wherein the nanowires are functionalized to align vertically and assemble into a nanowire aggregate at the interface, with said wire portion in the first phase and said head portion in the second phase; providing a bonding substance to one of said first or second phases; bonding the nanowires of the nanowire aggregate in said one phase using said substance.

Description

[Technical Field] This invention relates to the formation of nanowire devices, and more specifically, to the picking and aligning of nanowires to manufacture nanowire devices. More specifically, this invention relates to the self-fluidic supply of aggregates of polymerized and aligned nanowires (e.g.) to subsequently transfer the aggregates of aligned nanowires to a substrate surface. [Previous Technology] Conventional techniques for capturing nanostructures on surfaces focus on aligning and capturing / depositing nanostructures with low length-to-diameter ratios (e.g., nanorods, nanoparticles). However, it is more difficult to capture and align nanostructures with larger length-to-diameter ratios (e.g., nanowires). It is also difficult to align nanowires with a preferred orientation. Conventional techniques may require external equipment or external control under high pressure (e.g., by applying an electric field, slow solvent evaporation, or thermal annealing) to achieve the alignment and capture / deposition of nanostructures. Such external control increases production costs and reduces the scalability of nanodevice production. Furthermore, existing techniques for the vertical alignment of nanostructures with high aspect ratios are limited to small areas, below the cm scale. The applicant's previous application (published as WO2015 / 166416 A1) discloses a method for extracting and aligning an assembly of nanowires from a liquid interface onto a surface. The method includes providing a first liquid and a second liquid, wherein the first liquid phase and the second liquid phase are separated into a bottom phase, a top phase, and an interface between the bottom phase and the top phase. Providing the nanowires such that most of the nanowires are positioned at the interface and providing the nanowires to a substrate such that most of the nanowires are aligned relative to each other on the substrate. There is still room for improvement in the technique for providing a suitable assembly of nanowires (suitable for extracting an assembly from a substrate surface). More specifically, improvements are needed to achieve higher quality in the process of transferring the nanowire assembly from a fluid to a substrate surface and in terms of the integrity of the resulting substrate. [Summary of the Invention] This paper presents a solution to the problem of providing assemblies of oriented nanowires via self-fluidization. According to the present paper, a method for forming aggregated aligned nanowires is proposed, wherein the nanowires include elongated line portions and head portions located at a first end of the elongated line portions. The method includes: providing a fluid comprising a first liquid, a second liquid, and a plurality of nanowires, wherein the first liquid phase and the second liquid phase are separated into a first phase, a second phase, and an interface between the first phase and the second phase; wherein the nanowires are functionalized to be vertically aligned and aggregated into a nanowire aggregate at the interface, wherein the line portions are located in the first phase and the head portions are located in the second phase; providing a bonding material to one of the first phase and the second phase; and using the material to bond the nanowires of the nanowire aggregate in the phase. In an embodiment, the bonding material is a precursor material of a compound added to the first phase, and the bonding step includes: growing the compound on the line portions to bond the line portions of adjacent nanowires together. In an embodiment, the nanowires have a dielectric layer on their respective portions. In an embodiment, the dielectric layer on the nanowires is formed from the compound. In an embodiment, the compound is grown to substantially fill the spaces between the nanowire portions of the nanowire aggregate. In an embodiment, the bonding material is a silicon dioxide precursor of a silicon dioxide compound or an alumina precursor of an alumina compound. In an embodiment, the step of bonding the nanowires includes: growing an organic silicon dioxide compound on the nanowire portions. In an embodiment, the method includes the steps of: providing a second bonding material to the second phase; forming a bonding layer bonded to the nanowire portions from the second material. In an embodiment, the method includes: contacting the nanowire aggregate with a carrier member; drying the nanowire aggregate; removing the bonding between the nanowire portions; and providing a matrix material between the nanowires of the nanowire aggregate. In an embodiment, the method includes: removing the material layer from the nanowire aggregate; providing an electrical contact connected to one of the first ends of the nanowires. In an embodiment, the second bonding material is a monomeric or polymeric material. In an embodiment, wherein the bonding material is a polymeric or monomeric material added to the second phase, and the bonding step includes: growing a bonding layer from the bonding material bonded to the head portions. In an embodiment, the fluid has a moderating substance in a composition configured to resist bulging at the interface. In an embodiment, the method includes: providing the nanowires in the second liquid before combining the second liquid and the first liquid. In an embodiment, the method includes the step of: adding a subsequent amount of the second liquid to the top layer phase such that a plurality of nanowire aggregates are interconnected into a larger continuous nanowire aggregate. In an embodiment, the moderating substance increases the relative density of the bottom layer phase relative to the top layer phase. In an embodiment, the method includes: modifying the composition of the bottom layer phase after forming the nano-aggregate.In an embodiment, the composition of the underlying phase is modified by extracting a certain amount of the first liquid from the underlying phase and adding a certain amount of liquid to the underlying phase, wherein the added amount of liquid has a composition different from that of the extracted amount of liquid. In an embodiment, modifying the composition of the underlying phase includes: providing the first liquid to the underlying phase having a first concentration of the substance exceeding a first standard before providing the nanowires to the fluid, and changing the concentration of the substance in the underlying phase to a second concentration below a second standard after the formation of the nano-aggregates, which is lower than the first concentration. In an embodiment, the modifying substance includes at least one of acetone, acetonitrile, dimethyl sulfoxide, ethylene glycol, dioxane, dimethoxyethane, dimethylformamide, tert-butanol, 2-propanol, and isopropanol, wherein the modifying substance is provided in the first liquid in a composition having a solvent within a predetermined concentration range. In an embodiment, the modifying substance includes hexane provided in the first liquid in a composition having a solvent within a predetermined concentration range. In an embodiment, the regulating substance is provided to the concentration in water. In an embodiment, the nanowires are functionalized by a compound comprising a molecular chain attached to the head portion. In an embodiment, the head portion comprises particles, and the molecular chain is a thiol attached to the particles by a sulfur atom. In an embodiment, the compound is 1-octadecylthiol or polyethyleneimine. In an embodiment, the method includes: functionalizing the nanowires with a compound of the second liquid. In an embodiment, the method includes: contacting the nanowire aggregate with a carrier member; and drying the nanowire aggregate. In an embodiment, the carrier member is a substrate surface. According to a second embodiment, an aggregate of vertically aligned nanowires is provided, wherein the nanowires include elongated line portions and head portions located at a first end of the elongated line portions, the aggregate including a binder configured to fix the nanowires in the aggregate. In an embodiment, the binder comprises a compound grown on the line portions of the aligned line portions to form a matrix connecting the nanowires. In one embodiment, the wire portion has a dielectric shell, and the binder is grown on the shell. In another embodiment, the binder and the shell are formed from a common compound. In yet another embodiment, the aggregate is formed by a method according to any of the preceding steps. In yet another embodiment, the nanowire device includes a nanowire film comprising: a substrate; and an aggregate of vertically aligned nanowires according to any of the preceding embodiments, connected to the substrate. In yet another embodiment, the nanowires are non-epitaxically connected to the substrate after the aggregate is formed. In yet another embodiment, a photovoltaic device includes a nanowire device according to any of the preceding embodiments. In yet another embodiment, a lithium-ion battery includes a nanowire device according to any of the preceding embodiments. In yet another embodiment, a thermoelectric device includes a nanowire device according to any of the preceding embodiments.In this embodiment, the heat dissipation film includes any of the nanowire devices of the previous embodiments.

Implementation Method

Claims

1. A method for forming an aggregate of aligned nanowires, wherein the nanowires include an elongated portion and a head portion located at a first end of the elongated portion, the method comprising: A fluid comprising a first liquid, a second liquid, and a plurality of nanowires is provided, wherein the first liquid phase and the second liquid phase are separated into a first phase, a second phase, and an interface between the first phase and the second phase; wherein the nanowires are functionalized to be vertically aligned and aggregated into a nanowire aggregate at the interface, wherein the wire portion is located in the first phase and the head portion is located in the second phase; a bonding material is provided to one of the first phase or the second phase; and the material is used to bond the nanowires of the nanowire aggregate in the first phase.

2. The method of claim 1, wherein the bonding material is a precursor material of the compound added to the first phase, and the bonding step comprises: growing the compound on the wire portions to bond the wire portions of adjacent nanowires together.

3. The method of claim 2, wherein the line portions of the nanowires have a dielectric layer.

4. The method of claim 3, wherein the dielectric layer on the line is formed of the compound.

5. The method of any one of claims 2 to 4, wherein the compound is grown to substantially fill the space between the linear portions of the nanowire aggregate.

6. The method of any one of claims 1 to 4, wherein the bonding material is a silica precursor of a silica compound or an alumina precursor of an alumina compound.

7. The method of any one of claims 1 to 4, wherein the step of bonding the nanowires comprises: growing an organic silicon dioxide compound on the nanowire portions.

8. The method of any of requests 1 to 4, comprising the following steps: A second bonding material is provided to the second phase; a bonding layer is formed from the second material, and the bonding layer is bonded to the head portion.

9. The method as described in claim 8, which includes: Make the nanowire aggregate come into contact with the carrier component; Dry the nanowire aggregate; Remove the joint between the equal lines; A matrix material is provided between the nanowires of the nanowire aggregate.

10. The method of request item 9 includes the following steps: Remove the material layer from the nanowire aggregate; provide electrical contacts to the first ends of the nanowires.

11. The method of claim 8, wherein the second bonding material is a monomeric or polymeric material.

12. The method of claim 1, wherein the bonding substance is a polymer or monomer material added to the second phase, and the bonding step comprises: growing a bonding layer from the bonding substance bonded to the head portion.

13. The method of any one of claims 1 to 4, wherein the fluid has a conditioning substance in a composition configured to resist bulging of the interface.

14. The method of claim 13, wherein the nanowires are provided in the second liquid before combining the second liquid and the first liquid.

15. The method of request item 13, which includes the following steps: The second liquid is then added to the top layer phase, causing multiple nanowire assemblies to interconnect into a larger continuous nanowire assembly.

16. The method of claim 13, wherein the modifier increases the relative density of the bottom phase relative to the top phase.

17. The method of claim 13, comprising: The composition of the underlying phase is altered after the formation of the nanowire aggregates.

18. The method of claim 17, wherein the composition of the underlying phase is altered by extracting a certain amount of the first liquid from the underlying phase and adding a certain amount of liquid to the underlying phase, wherein the added amount of liquid has a composition different from that of the extracted amount of liquid.

19. The method of claim 17, wherein changing the composition of the underlying phase comprises: providing a first liquid to the underlying phase having a first concentration of the substance exceeding a first standard before providing the nanowires to the fluid, and changing the concentration of the substance in the underlying phase to a second concentration below a second standard, which is lower than the first concentration, after forming the nanowire aggregates.

20. The method of claim 13, wherein the modifier comprises at least one of acetone, acetonitrile, dimethyl sulfoxide, diethylene glycol, dioxane, dimethoxyethane, dimethylformamide, tert-butanol, 2-propanol, and isopropanol, wherein the modifier is provided in the first liquid in a composition having a solvent within a predetermined concentration range.

21. The method of claim 13, wherein the conditioning substance comprises hexane provided in the first liquid in a composition having a solvent within a predetermined concentration range.

22. The method of claim 20, wherein the conditioning substance is set to the concentration in the water.

23. The method of any one of claims 1 to 4, wherein the nanowires are functionalized by means of a compound comprising a molecular chain attached to the head portion.

24. The method of claim 23, wherein the head portion comprises a particle and the molecular chain is composed of a sulfur atom linked to a thiol of the particle.

25. The method of claim 23, wherein the compound is 1-octadecylthiol or polyethyleneimine.

26. The method of claim 23, wherein the nanowires are functionalized by means of a compound of the second liquid.

27. The method of any of claims 1 to 4, comprising: Make the nanowire aggregate come into contact with the carrier component; The nanowire aggregate was dried.

28. The method of claim 27, wherein the carrier member is the surface of a substrate.

29. An aggregate of vertically aligned nanowires, wherein the nanowires include elongated line portions and head portions located at a first end of the elongated line portions, the aggregate including a binder configured to fix the nanowires in the aggregate.

30. The aggregate of claim 29, wherein the binder comprises a compound grown on the line portions of the aggregate alignment portions to form a matrix connecting the nanowires.

31. The aggregate of claim 29, wherein the linear portions have a dielectric shell and the binder is grown on the shell.

32. An aggregate as claimed in claim 31, wherein the binder and the shell are formed of a common compound.

33. An aggregate of any of claims 29 to 32, formed by means of any of claims 1 to 28.

34. A nanowire device comprising a nanowire film including: a substrate; and an aggregate of vertically aligned nanowires according to any one of claims 29 to 33, connected to the substrate.

35. The nanowire device of claim 34, wherein the nanowires are non-epitaxically connected to the substrate after the aggregate is formed.

36. A photovoltaic device including the nanowire device of claim 34 or 35.

37. A lithium-ion battery comprising the nanowire device of claim 34 or 35.

38. A thermoelectric device comprising the nanowire device of claim 34 or 35.

39. A heat dissipation membrane comprising the nanowire device of claim 34 or 35.

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