Eliminating emissive sub-bandgap states in nanocrystals

Patent metadata

Field	Value
Publication number	US-10109760-B2
Application number	US-201615095001-A
Country	US
Kind code	B2
Filing date	Apr 8, 2016
Priority date	Apr 9, 2015
Publication date	Oct 23, 2018
Grant date	Oct 23, 2018

Abstract

The size-dependent band-gap tunability and solution processability of nanocrystals (NCs) make them attractive candidates for optoelectronic applications. One factor that presently limits the device performance of NC thin films is sub-bandgap states, also referred to as trap states. Trap states can be controlled by surface treatment of the nanocrystals.

First claim

What is claimed is:

1. A method of modifying a surface of nanocrystal including contacting a surface of the nanocrystal with an oxidizing agent, wherein the nanocrystal is a Group II-VI compound, a Group II-V compound, a Group III-VI compound, a Group III-V compound, a Group IV-VI compound, a Group I-III-VI compound, a Group II-IV-VI compound, or a Group II-IV-V compound,
treating the surface with the oxidizing agent until a density of trap states for the nanocrystal having the oxidized surface compared to the nanocrystal having an untreated surface is reduced by at least 20-fold and
removing under-charged atoms on the surface.

2. The method of claim 1 , wherein the nanocrystal includes Pb.

3. The method of claim 1 , wherein the nanocrystal includes S.

4. The method of claim 1 , wherein the nanocrystal includes Se.

5. The method of claim 1 , wherein the oxidizing agent is selected from the group consisting of 1, 4-benzoquinone, dithiothreitol, 2,3-dichloro-5,6-dicyanobenzoquinone, 3,3′,5,5′-tetra-tert-butyldiphenoquinone, di-tert-butyl peroxide, I 2 , I 2 /I − (I 3 − ), chlorine gas, bromine, ozone, O 2 plasma treatment, and an acid, or combinations thereof.

6. The method of claim 1 , wherein the oxidizing agent is pyruvic acid and the method includes annealing.

7. The method of claim 1 , wherein contacting a surface of the nanocrystal with the oxidizing agent to oxidize metal atom of the nanocrystal atoms at the surface.

8. A method of treating a film that includes nanocrystal comprising contacting a surface of the nanocrystal with an oxidizing agent, wherein the nanocrystal is a Group II-VI compound, a Group II-V compound, a Group III-VI compound, a Group III-V compound, a Group IV-VI compound, a Group I-III-VI compound, a Group II-IV-VI compound, or a Group II-IV-V compound,
forming a modified surface in which a density of trap states for the nanocrystal having the oxidized surface compared to the nanocrystal having an untreated surface is reduced by at least 20-fold and
removing under-charged atoms on the film with the oxidizing agent.

9. The method of claim 8 , wherein the nanocrystal includes Pb.

10. The method of claim 8 , wherein the nanocrystal includes S.

11. The method of claim 8 , wherein the nanocrystal includes Se.

12. The method of claim 8 , wherein the oxidizing agent is selected from the group consisting of 1, 4-benzoquinone, dithiothreitol, 2,3-dichloro-5,6-dicyanobenzoquinone, 3,3′,5,5′-tetra-tert-butyldiphenoquinone, di-tert-butyl peroxide, I 2 , I 2 /I − (I 3 − ), chlorine gas, bromine, ozone, O 2 plasma treatment, and an acid, or combinations thereof.

13. The method of claim 8 , wherein the oxidizing agent is pyruvic acid and the method includes annealing.

14. The method of claim 8 , wherein contacting a surface of the nanocrystal with the oxidizing agent to oxidize metal atom of the nanocrystal atoms at the surface.

15. The method of claim 8 , wherein contacting the surface of the nanocrystal with the oxidizing agent is dispensing the oxidizing agent onto the film.

16. The method of claim 1 , wherein the oxidizing agent is selected from the group consisting of H 2 SO 4 , HNO 3 , 1, 4-benzoquinone, dithiothreitol, 2,3-dichloro-5,6-dicyanobenzoquinone, 3,3′,5,5′-tetra-tert-butyldiphenoquinone, di-tert-butyl peroxide, I 2 , I 2 /I − (I 3 − ), and pyruvic acid.

17. The method of claim 8 , wherein the oxidizing agent is selected from the group consisting of H 2 SO 4 , HNO 3 , 1, 4-benzoquinone, dithiothreitol, 2,3-dichloro-5,6-dicyanobenzoquinone, 3,3′,5,5′-tetra-tert-butyldiphenoquinone, di-tert-butyl peroxide, I 2 , I 2 /I − (I 3 − ), and pyruvic acid.

18. The method of claim 1 , wherein the oxidizing agent is selected from the group consisting of 1, 4-benzoquinone, dithiothreitol, 2,3-dichloro-5,6-dicyanobenzoquinone, 3,3′,5,5′-tetra-tert-butyldiphenoquinone, di-tert-butyl peroxide, I 2 , I 2 /I − (I 3 − ), bromine, ozone, and an acid, or combinations thereof.

19. The method of claim 8 , wherein the oxidizing agent is selected from the group consisting of 1, 4-benzoquinone, dithiothreitol, 2,3-dichloro-5,6-dicyanobenzoquinone, 3,3′,5,5′-tetra-tert-butyldiphenoquinone, di-tert-butyl peroxide, I 2 , I 2 /I − (I 3 − ), bromine, ozone, and an acid, or combinations thereof.

Assignees

• Massachusetts Inst Technology

Inventors

• Hwang Gyuweon
• Kim Donghun
• Cordero Jose M
• Wilson Mark W B
• Chuang Chia-Hao M
• Grossman Jeffrey C
• Bawendi Moungi G

Classifications

• C09K11/668 Primary

  Sulfates · CPC title

• H01L31/0445

  Electricity · mapped topic

• H01L51/42

  Electricity · mapped topic

• H01L31/036

  Electricity · mapped topic

• H01L31/18 Primary

  Electricity · mapped topic