Uniform transfer of luminescent quantum dots onto a substrate
View Patent ↗A method of uniformly transferring luminescent quantum dots onto a substrate, comprising: a) preparing a colloidal suspension of luminescent quantum dots in a hydrophobic solvent, wherein the density of the hydrophobic solvent is from 0.67 g/cm 3 to 0.96 g/cm 3 ; b) dispensing the suspension onto a convex aqueous surface; c) allowing the hydrophobic solvent to evaporate; d) contacting the film of luminescent quantum dots with a hydrophobic stamp; and e) depositing the film of luminescent quantum dots onto a substrate with the hydrophobic stamp is described herein. Further described is a method of preparing quantum dot based light emitting diodes.
1. A method of uniformly transferring luminescent quantum dots onto a substrate, comprising:
a) preparing a colloidal suspension of luminescent quantum dots in a hydrophobic solvent, wherein the density of the hydrophobic solvent is from 0.67 g/cm 3 to 0.96 g/cm 3 ;
b) dispensing the suspension onto a convex aqueous surface;
c) allowing the hydrophobic solvent to evaporate, thereby forming a film of luminescent quantum dots;
d) contacting the film of luminescent quantum dots with a hydrophobic stamp; and
e) depositing the film of luminescent quantum dots onto a substrate with the hydrophobic stamp.
2. The method of claim 1 , further comprising precipitating and re-suspending the luminescent quantum dots in a non-polar solvent prior to the step of preparing the suspension.
3. The method of claim 2 , wherein the non-polar solvent is hexane.
4. The method of claim 1 , wherein the colloidal suspension of luminescent quantum dots is prepared in a mixture of two hydrophobic solvents.
5. The method of claim 4 , wherein the mixture of two hydrophobic solvents is a mixture of hexane and 1,2-dichloroethane.
6. The method of claim 5 , wherein the mixture of hexane and 1,2-dichloroethane is a 1:1 mixture.
7. The method of claim 1 , wherein the hydrophobic stamp is formed from polydimethylsiloxane.
8. The method of claim 1 , wherein the substrate is a silicon based substrate.
9. The method of claim 1 , wherein the substrate with the film of luminescent quantum dots is used in a light emitting diode.
10. The method of claim 1 , wherein the luminescent quantum dots are formed of CdSe:ZnS.
11. The method of claim 1 , wherein the thickness of the film deposited onto the substrate is from 25 nm to 55 nm.
12. The method of claim 11 , wherein the thickness of the film deposited onto the substrate is from 30 nm to 50 nm.
13. The method of claim 11 , wherein the thickness of the film deposited onto the substrate is from 35 nm to 45 nm.
14. A method of preparing quantum dot based light emitting diodes, comprising:
a) preparing a colloidal suspension of luminescent quantum dots in a hydrophobic solvent, wherein the density of the hydrophobic solvent is from 0.67 g/cm 3 to 0.96 g/cm 3 ;
b) dispensing the suspension onto a convex aqueous surface;
c) allowing the hydrophobic solvent to evaporate, thereby forming a film of luminescent quantum dots;
d) contacting the film of luminescent quantum dots with a hydrophobic polydimethylsiloxane stamp; and
e) depositing one or more layers of the film of luminescent quantum dots onto a silicon substrate.
15. The method of claim 14 , further comprising depositing a plurality of layers of the film of luminescent quantum dots onto the silicon substrate.
16. The method of claim 14 , wherein the luminescent quantum dots are formed of material selected from CdSe:ZnS.
17. The method of claim 15 , wherein the luminescent quantum dots are formed of material selected from CdSe:ZnS.