QUANTUM DOT-FULLERENE JUNCTION OPTOELECTRONIC DEVICES

• US 20120241723A1
• Filed: 09/29/2010
• Published: 09/27/2012
• Est. Priority Date: 09/29/2009
• Status: Active Grant

• Current Assignee: Research Triangle Institute
• Original Assignee: Research Triangle Institute International
• Inventors: Klem, Ethan, Lewis, John
• Granted Patent: US 8,729,528 B2
• Time in Patent Office: Days
• US Class Current: 257/21
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: H10K 10/466 Lateral bottom-gate IGFETs comprising only a single gate
• CPC Class Codes: H10K 10/486 the channel region comprising two or more active layers, e.g. forming pn heterojunctions
• CPC Class Codes: H10K 2102/101 comprising transparent conductive oxides [TCO]
• CPC Class Codes: H10K 30/10 comprising heterojunctions between organic semiconductors and inorganic semiconductors
• CPC Class Codes: H10K 30/15 Sensitised wide-bandgap semiconductor devices, e.g. dye-sensitised TiO2 photo-electrochemical devices comprising a liquid electrolyte or a solid electrolyte H01G9/20
• CPC Class Codes: H10K 39/30 Devices controlled by radiation
• CPC Class Codes: H10K 85/211 Fullerenes, e.g. C60
• CPC Class Codes: Y02E 10/549 Organic PV cells

Abstract

An optoelectronic device includes a first electrode, a quantum dot layer disposed on the first electrode including a plurality of quantum dots, a fullerene layer disposed directly on the quantum dot layer wherein the quantum dot layer and the fullerene layer form an electronic heterojunction, and a second electrode disposed on the fullerene layer. The device may include an electron blocking layer. The quantum dot layer may be modified by a chemical treatment to exhibit in creased charge carrier mobility.

Claims

1. An optoelectronic device, comprising:

a first electrode;

an electron blocking layer disposed on the first electrode;

a quantum dot layer disposed on the electron blocking layer and comprising a plurality of quantum dots;

a fullerene layer disposed directly on the quantum dot layer, wherein the quantum dot layer and the fullerene layer form an electronic heterojunction; and

a second electrode disposed on the fullerene layer.

2. The optoelectronic device of claim 1, wherein the first electrode or the second electrode is selected from the group consisting of conductive oxides, metals, metal alloys, metal-inclusive compounds, CNTs, and conductive polymers.

3. The optoelectronic device of claim 1, wherein the quantum dots are selected from the group consisting of visible light-sensitive quantum dots, infrared-sensitive quantum dots, and ultraviolet-sensitive quantum dots.

4. The optoelectronic device of claim 1, wherein the quantum dots have a composition selected from the group consisting of Group II-VI, Group I-III-VI, Group III-V, Group IV, Group IV-VI, and Group V-VI materials.

5. The optoelectronic device of claim 1, wherein the quantum dots are composed of lead sulfide, lead selenide, lead telluride, mercury telluride, or alloys thereof.

6. The optoelectronic device of claim 1, wherein the quantum dot layer has a thickness ranging from 5 nm to 5 μ

m.

7. The optoelectronic device of claim 1, wherein the plurality of quantum dots comprises a plurality of first quantum dots and a plurality of second quantum dots, and the first quantum dots have a first average size and the second quantum dots have a second average size different from the first average size, or the first quantum dots have a first composition and the second quantum dots have a second composition different from the first composition.

8. The optoelectronic device of claim 1, wherein the fullerenes are selected from the group consisting of C_n fullerenes where n is 20 or greater, endohedral fullerenes, fullerene derivatives, and a combination of two or more of the foregoing.

9. The optoelectronic device of claim 1, wherein the fullerene layer has a thickness ranging from 3 nm to 300 nm.

10. The optoelectronic device of claim 1, further comprising a hole blocking layer disposed on the fullerene layer, wherein the second electrode is disposed on the hole blocking layer.

11. The optoelectronic device of claim 10, wherein the hole blocking layer has a composition selected from the group consisting of titanium oxides, zinc oxides, BCP, BPhen, NBPhen, metal chelates, and chemical relatives and derivatives of the foregoing.

12. The optoelectronic device of claim 1, wherein the electron blocking layer has a composition selected from the group consisting of molybdenum oxides, tungsten oxides, copper oxides, nickel oxides, phthalocyanines, m-MTDATA, α

-NPD, quantum dots, and chemical relatives and derivatives of the foregoing.

13. The optoelectronic device of claim 1, wherein the electron blocking layer comprises a discontinuous layer.

14. The optoelectronic device of claim 13, wherein the electron blocking layer comprises a pattern of electron blocking material.

15. The optoelectronic device of claim 1, further comprising an exciton blocking layer disposed on the fullerene layer or on the first electrode.

16. The optoelectronic device of claim 1, wherein the quantum dot layer exhibits a charge carrier mobility greater than 1×

10<sup>−

4</sup> cm²/V-sec.

17. The optoelectronic device of claim 1, wherein the quantum dot layer exhibits a charge carrier mobility ranging from greater than 1×

10<sup>−

4</sup> cm²/V-sec to 10 cm²/V-sec.

18. The optoelectronic device of claim 1, wherein the quantum dot layer is a chemically treated quantum dot layer that exhibits increased charge carrier mobility relative to an untreated quantum dot layer.

19. The optoelectronic device of claim 1, wherein the quantum dot layer exhibits an interparticle spacing of 2 nm or less.

20. The optoelectronic device of claim 1, wherein the optoelectronic device has a power conversion efficiency of at least 4.5% when illuminated by an incident white light beam of 100 mW/cm².

21. (canceled)

22. (canceled)

23. (canceled)

24. (canceled)

25. A method for fabricating an optoelectronic device, the method comprising:

depositing an electron blocking layer on an electrode;

depositing a quantum dot layer on the electron blocking layer, the quantum dot layer comprising a plurality of quantum dots; and

depositing a fullerene layer directly on the quantum dot layer, wherein the quantum dot layer and the fullerene layer form an electronic heterojunction.

26. The method of claim 25, wherein depositing the quantum dot layer comprises depositing a solution comprising the plurality of quantum dots and a solvent.

27. The method of claim 25, wherein the solvent is selected from the group consisting of toluene, anisole, alkanes, butylamine, and water.

28. The method of claim 25, wherein depositing the quantum layer comprises depositing a first quantum dot film on the fullerene layer, followed by depositing one or more additional quantum dot films on the first quantum dot film.

29. The method of claim 25, comprising, after depositing the quantum dot layer or one or more additional quantum dot films, treating the quantum dot layer or one or more of the additional quantum dot films with a chemistry that increases a charge carrier mobility of the quantum dot layer.

30. The method of claim 29, wherein the chemistry comprises a solution or vapor having a composition selected from the group consisting of ethanethiol, alkyl-thiols, alkenyl-thiols, alkynyl-thiols, aryl-thiols, ethanedithiol, benzendithiol, alkyl-polythiols, alkenyl-polythiols, alkynyl-polythiols, aryl-polythiols, carboxlyic acids, formic acid, methanol, toluene, isopropyl alchohol, chloroform, acetonitrile, acetic acid, butyl amine, 1,4 butyl diamine, alkyl-amines, alkenyl-amines, alkynyl-amines, aryl-amines alkyl-polyamines, alkenyl-polyamines, alkynyl-polyamines, aryl-polyamines.

31. The method of claim 25, further comprising depositing a hole blocking layer or an exciton blocking layer on the fullerene layer.

32. The method of claim 25, further comprising depositing an exciton blocking layer on the electrode.

33. A method for fabricating an optoelectronic device, the method comprising:

depositing a quantum dot layer on an electrode, the quantum dot layer comprising a plurality of quantum dots;

treating the quantum dot layer with a chemistry that increases charge carrier mobility in the quantum dot layer; and

depositing a fullerene layer directly on the quantum dot layer, wherein the quantum dot layer and the fullerene layer form an electronic heterojunction.

34. The method of claim 33, comprising depositing an electron blocking layer on the electrode, wherein the quantum dot layer is deposited on the electron blocking layer.

35. The method of claim 33, comprising subjecting the electron blocking layer to an oxidizing or reducing treatment.

36. The method of claim 33, comprising treating the quantum dot layer with a chemistry selected from a chemistry that reduces an interparticle spacing between quantum dots, a chemistry that reduces an as-deposited thickness of the quantum dot layer, or a chemistry that both reduces the interparticle spacing and the as-deposited thickness of the quantum dot layer.

37. The method of claim 36, comprising reducing the interparticle spacing to 2 nm or less, or reducing the as-deposited thickness by 20 to 80%.