Transfer of monolayer graphene onto flexible glass substrates
Described herein are methods for improved transfer of graphene from formation substrates to target substrates. In particular, the methods described herein are useful in the transfer of high-quality chemical vapor deposition-grown monolayers of graphene from metal, e.g., copper, formation substrates to ultrathin, flexible glass targets. The improved processes provide graphene materials with less defects in the structure.
1. A process for forming a graphene-coated glass comprising:
a. forming a clean ultrathin, flexible glass substrate, comprising:
i. applying an O 2 plasma treatment to an ultrathin, flexible glass substrate;
ii. applying an organic base and peroxide solution to the ultrathin, flexible glass substrate; and
iii. applying an acid and peroxide solution to the ultrathin, flexible glass substrate;
wherein the ultrathin, flexible glass substrate has a thickness of from about 10 μm to about 300 μm;
b. contacting a chemical vapor deposition-grown graphene on a formation substrate with a thermal release tape to form a stack;
c. applying a pressing force of from about 100 to about 1000 psi to the stack to adhere the thermal release tape to the graphene, then removing of the pressing force;
d. etching away the formation substrate in an etchant solution;
e. contacting the clean ultrathin, flexible glass substrate with the graphene to form a sandwich comprising the thermal release tape, graphene, and ultrathin, flexible glass substrate, and placing the sandwich in a press;
f. applying a pressing force of from about 75 to about 300 psi to the sandwich to adhere the graphene to the ultrathin, flexible glass substrate, then removing of the pressing force; and
g. heating the sandwich to a temperature about 1° to about 10° C. above the release temperature of the thermal release tape to remove the thermal release tape without damage to the graphene or ultrathin, flexible glass substrate, or removal of the graphene from the ultrathin, flexible glass substrate.
2. The process of claim 1 , wherein the process further comprises between steps c. and d., the step of contacting the stack with an acid to remove any graphene on the formation substrate not within the stack.
3. The process of claim 1 , wherein the acid comprises nitric acid, sulfuric acid, or hydrochloric acid, or combinations thereof.
4. The process of claim 1 , wherein the process further comprises an additional cleaning step comprising washing the graphene and ultrathin, flexible glass substrate with one or more organic solvents to remove any residual thermal release tape residues.
5. The process of claim 1 , wherein the solvent comprises methanol, ethanol, toluene, benzene, acetone, or a combination thereof.
6. The process of claim 1 , wherein the etchant comprises iron chloride, ammonium persulfate, iron nitrate, copper chloride, copper sulfate, hydrochloric acid, hydroboric acid, nitric acid, sulfuric acid, sodium hydroxide, hydrogen peroxide, chromium oxide, phosphoric acid, or combinations thereof.
7. The process of claim 1 , wherein the pressing force on the stack is from about 150 psi to about 800 psi.
8. The process of claim 1 , wherein the pressing force on the sandwich is from about 100 to about 200 psi.
9. The process of claim 1 , wherein the sandwich is heated to a temperature about 1 o to about 5° C. above the release temperature.
10. The process of claim 1 , wherein in step a., the organic base is selected from the group of KOH, NH 4 0H, NaOH, Ca(OH) 2 and combinations thereof; the acid is selected from the group of hydrochloric acid, hydroboric acid, nitric acid, sulfuric acid, phosphoric acid, and combinations thereof; and the peroxide is selected from the group of hydrogen peroxide.
11. The process of claim 1 , wherein the ultrathin, flexible glass substrate is on a roll.
12. The process of claim 1 , wherein the ultrathin, flexible glass substrate is supported on a second substrate, thicker substrate.
13. A process for forming a graphene-coated glass comprising:
a. forming a clean ultrathin, flexible glass substrate, comprising:
i. applying an O 2 plasma treatment to an ultrathin, flexible glass substrate;
ii. applying an organic base and peroxide solution to the ultrathin, flexible glass substrate; and
iii. applying an acid and peroxide solution to the ultrathin, flexible glass substrate;
wherein the ultrathin, flexible glass substrate has a thickness of from about 10 μm to about 300 μm;
b. coating a chemical vapor deposition-grown graphene with a polymer and polymerizing the polymer;
c. contacting the clean ultrathin, flexible glass substrate with the graphene to form a stack comprising the polymer, graphene, and ultrathin, flexible glass substrate; and
d. dissolving the polymer by contacting the polymer with an organic solvent.
14. The process of claim 13 , wherein the polymer comprises a polymethylmethacrylate (PMMA) or polydimethylsiloxane (PDMS).
15. The process of claim 13 , wherein in step a., the organic base is selected from the group of KOH, NIL 4 OH, NaOH, Ca(OH) 2 and combinations thereof; the acid is selected from the group of hydrochloric acid, hydroboric acid, nitric acid, sulfuric acid, phosphoric acid, and combinations thereof; and the peroxide is selected from the group of hydrogen peroxide.
16. The process of claim 13 , wherein the process further comprises an additional cleaning step comprising washing the graphene and ultrathin, flexible glass substrate with one or more organic solvents to remove any residual thermal release tape residues.
17. The process of claim 13 , wherein the solvent comprises methanol, ethanol, toluene, benzene, acetone, or a combination thereof.
18. The process of claim 13 , wherein the ultrathin, flexible glass substrate is on a roll.
19. The process of claim 13 , wherein the ultrathin, flexible glass substrate is supported on a second substrate, thicker substrate.
20. The process of claim 1 , wherein the O 2 plasma treatment is applied before the organic base and peroxide solution is applied, and the organic base and peroxide solution is applied before the acid and peroxide solution is applied.