Quantum dot optical devices with enhanced gain and sensitivity and methods of making same
Optical and optoelectronic devices and methods of making same. Under one aspect, an optical device includes an integrated circuit an array of conductive regions; and an optically sensitive material over at least a portion of the integrated circuit and in electrical communication with at least one conductive region of the array of conductive regions. Under another aspect, a method of forming a nanocrystalline film includes fabricating a plurality of nanocrystals having a plurality of first ligands attached to their outer surfaces; exchanging the first ligands for second ligands of different chemical composition than the first ligands; forming a film of the ligand-exchanged nanocrystals; removing the second ligands; and fusing the cores of adjacent nanocrystals in the film to form an electrical network of fused nanocrystals. Under another aspect, a film includes a network of fused nanocrystals, the nanocrystals having a core and an outer surface, wherein the core of at least a portion of the fused nanocrystals is in direct physical contact and electrical communication with the core of at least one adjacent fused nanocrystal, and wherein the film has substantially no defect states in the regions where the cores of the nanocrystals are fused.
1. A device comprising:
an array of conductive regions forming a first portion of a monolithic integrated circuit, the array of conductive regions comprising pixel regions;
an optically sensitive material formed over at least a portion of the monolithic integrated circuit and in electrical communication with at least one conductive region of the array of conductive regions; and
a readout circuit formed on the monolithic integrated circuit, the readout circuit to activate at least one pixel in the array of pixel regions by applying an electrical signal to a control lead in electrical communication with the at least one pixel so that current flows through the optically sensitive layer and the at least one pixel.
2. The device of claim 1 , wherein the optically sensitive layer comprises an array of islands of optically sensitive material, wherein a plurality of the islands overlay a corresponding plurality of the conductive regions.
3. The device of claim 1 , wherein the monolithic integrated circuit includes three-dimensional features and wherein the optically sensitive material conforms to at least a portion of said three-dimensional features.
4. The device of claim 1 , further comprising an electrode overlaying and in electrical communication with at least a portion of the optically sensitive layer.
5. The device of claim 4 , wherein the electrode is at least partially transparent.
6. The device of claim 4 , wherein the electrode comprises at least one of a band-pass and a band-block material.
7. The device of claim 1 , wherein the conductive regions are arranged in one or more rows over the monolithic integrated circuit.
8. The device of claim 7 , wherein the conductive regions are further arranged in one or more columns over the monolithic integrated circuit.
9. The device of claim 1 , wherein the conductive regions are arranged in a plurality of rows and columns over the monolithic integrated circuit.
10. The device of claim 1 , wherein the monolithic integrated circuit includes a flexible substrate and is formed in a non-planar shape.
11. The device of claim 10 , wherein the monolithic integrated circuit comprises at least one of a semiconducting organic molecule and a semiconducting polymer.
12. The device of claim 1 , wherein the optically sensitive layer comprises a plurality of nanocrystals.
13. The device of claim 1 , wherein the optically sensitive layer comprises a plurality of fused nanocrystals, each nanocrystal having a core and an outer surface.
14. The device of claim 13 , wherein the outer surfaces of the fused nanocrystals are at least partially free of ligands.
15. The device of claim 13 , wherein the optically sensitive layer comprises a continuous film having nanoscale features, the nanoscale features comprising an interconnected network of fused nanocrystals, wherein substantially each fused nanocrystal includes a core in direct physical contact and electrical communication with the core of at least one adjacent nanocrystal.
16. The device of claim 15 , wherein the continuous film is substantially inorganic.
17. The device of claim 15 , wherein the continuous film comprises ligands on portions of the outer surface excluding portions where the nanocrystals have been fused.
18. The device of claim 15 , wherein the outer surface of substantially each fused nanocrystal comprises a material having a different composition from the core.
19. The device of claim 18 , wherein the outer surface of substantially each fused nanocrystal comprises oxidized core material.
20. The device of claim 18 , wherein the outer surface of substantially each fused nanocrystal comprises semiconductor material.
21. The device of claim 18 , wherein the outer surface of substantially each fused nanocrystal comprises at least one defect state.
22. The device of claim 1 , wherein the optically sensitive layer comprises an optically active polymer.
23. The device of claim 22 , wherein the optically active polymer comprises at least one of MEH-PPV, P30T, and P3HT.
24. The device of claim 1 , wherein the amount of current that flows through the optically sensitive layer and the pixel region is related to a number of photons received by the optically sensitive layer.
25. The device of claim 1 , wherein the monolithic integrated circuit comprises a CMOS active pixel.
26. The device of claim 1 , wherein the monolithic integrated circuit comprises a CCD pixel.
27. The device of claim 1 , wherein during operation an amount of current flowing in the optically sensitive layer is substantially linearly related to an amount of light received by the optically sensitive layer over at least a portion of its intended operating range.
28. The device of claim 1 , wherein the optically sensitive layer has a photoconductive gain of between about 1 and 1,000 A/W.
29. The device of claim 1 , wherein the optically sensitive layer has a photoconductive gain of between about 1 and 10,000 A/W.
30. The device of claim 1 , wherein the optically sensitive layer has a photoconductive gain of at least about 10,000 A/W.
31. The device of claim 1 , wherein the optically sensitive layer has a photoconductive gain of between about 100 and 10,000 A/W.
32. The device of claim 1 , wherein the optically sensitive layer has a noise equivalent exposure of less than about 10.11 J/cm 2 between the wavelengths of 400 nm and 800 nm.
33. The device of claim 1 , wherein the optically sensitive layer has a noise equivalent exposure of between about 10 −11 and 10 −12 J/cm 2 between the wavelengths of 400 nm and 800 nm.
34. The device of claim 1 , wherein the optically sensitive layer has a noise equivalent exposure of less than about 10 −10 J/cm 2 between the wavelengths of 400 nm and 1400 nm.
35. The device of claim 1 , wherein the optically sensitive layer has a noise equivalent exposure of less than about 10 −11 J/cm 2 in at least a portion of the spectrum between the wavelengths of 10 nm and 5 μm.
36. The device of claim 1 , wherein the optically sensitive layer has a noise equivalent exposure of less than about 10-12 J/cm2 in at least a portion of the spectrum between the wavelengths of 10 nm and 5 μm.
37. The device of claim 1 , wherein the optically sensitive layer has an electrical resistance of greater than about 25 k-Ohm/square.
38. The device of claim 1 , wherein the optically sensitive layer has a carrier mobility of between about 0.001 and about 10 cm 2 /Vs.
39. The device of claim 1 , wherein the optically sensitive layer has a carrier mobility of between about 0.01 and about 0.1 cm cm 2 /Vs.
40. The device of claim 1 , wherein the optically sensitive layer has a carrier mobility of greater than about 0.01 cm2/Vs.
41. A device comprising:
a plurality of electrodes; and
an optically sensitive layer between and in electrical communication with at least ones of the plurality of electrodes, the at least ones of the plurality of electrodes to provide a signal indicative of radiation absorbed by the optically sensitive layer, the optically sensitive layer to provide providing a photoconductive gain of at least about 100 A/W, the optically sensitive layer and the plurality of electrodes forming an array of pixel regions; and
a readout circuit to activate at least one pixel in the array of pixel regions by applying an electrical signal to a control lead in electrical communication with the at least one pixel so that current flows through at least a portion of the optically sensitive layer and the at least one pixel.
42. The device of claim 41 , wherein the optically sensitive layer has a photoconductive gain of at least about 1000 A/W.
43. The device of claim 41 , wherein the optically sensitive layer has a photoconductive gain of at least about 10,000 A/W.
44. The device of claim 41 , wherein the optically sensitive layer has a photoconductive gain of between about 100 and 10,000 A/W.
45. A device comprising:
a plurality of electrodes; and
an optically sensitive layer between and in electrical communication with at least ones of the plurality of electrodes, the at least ones of the plurality of electrodes to provide a signal indicative of radiation absorbed by the optically sensitive layer, the optically sensitive layer capable of a noise equivalent exposure of less than about 10 −11 J/cm 2 between the wavelengths of 400 nm and 800 nm, the optically sensitive layer and the plurality of electrodes forming an array of pixel regions; and
a readout circuit to activate at least one pixel in the array of pixel regions by applying an electrical signal to a control lead in electrical communication with the at least one pixel so that current flows through at least a portion of the optically sensitive layer and the at least one pixel.
46. The device of claim 45 , wherein the optically sensitive layer has a noise equivalent exposure of between about 10 −11 and 10 −12 J/cm 2 at 400 nm to 800 nm.
47. The device of claim 45 , wherein the optically sensitive layer has a noise equivalent exposure of less than about 10 −10 J/cm 2 at 400 to 1400 nm.
48. The device of claim 45 , wherein the optically sensitive layer has a photoconductive gain of at least about 100 A/W.
49. The device of claim 45 , wherein the optically sensitive layer has a photoconductive gain of at least about 1000 A/W.
50. The device of claim 45 , wherein the optically sensitive layer has a photoconductive gain of at least about 10,000 A/W.
51. A device comprising:
a plurality of electrodes; and
an optically sensitive layer between and in electrical communication with at least ones of the plurality of electrodes, the at least ones of the plurality of electrodes for providing to provide a signal indicative of radiation absorbed by the optically sensitive layer, the optically sensitive layer capable of a carrier mobility of greater than about 0.001 cm cm 2 /Vs, the optically sensitive layer and the plurality of electrodes forming an array of pixel regions; and
a readout circuit to activate at least one pixel in the array of pixel regions by applying an electrical signal to a control lead in electrical communication with the at least one pixel so that current flows through at least a portion of the optically sensitive layer and the at least one pixel.
52. The device of claim 51 , wherein the optically sensitive layer has a carrier mobility of between about 0.01 cm 2 /Vs and about 0.1 cm cm 2 /Vs.
53. The device of claim 51 , wherein the optically sensitive layer has a carrier mobility of up to about 10 cm 2 /Vs.