Materials, systems and methods for optoelectronic devices
A photodetector is described along with corresponding materials, systems, and methods. The photodetector comprises an integrated circuit and at least two optically sensitive layers. A first optically sensitive layer is over at least a portion of the integrated circuit, and a second optically sensitive layer is over the first optically sensitive layer. Each optically sensitive layer is interposed between two electrodes. The two electrodes include a respective first electrode and a respective second electrode. The integrated circuit selectively applies a bias to the electrodes and reads signals from the optically sensitive layers. The signal is related to the number of photons received by the respective optically sensitive layer.
1. A photodetector comprising:
at least two optically sensitive layers, a first optically sensitive layer and a second optically sensitive layer, the first optically sensitive layer over at least a portion of an integrated circuit and the second optically sensitive layer over the first optically sensitive layer;
wherein the first optically sensitive layer comprises a first absorption band including at least one first set of colors and is devoid of a local absorption maximum, and the second optically sensitive layer comprises a second absorption band including at least one second set of colors and is devoid of a local absorption maximum, wherein the second absorption band includes the first set of colors;
wherein each optically sensitive layer is interposed between a respective first electrode and a respective second electrode; and
wherein the integrated circuit selectively applies a bias to the electrodes and reads signals from the optically sensitive layers.
2. The photodetector of claim 1 , wherein the second optically sensitive layer is relatively completely absorbent of light in a first wavelength interval and relatively completely transmissive of light outside the first wavelength interval.
3. The photodetector of claim 2 , wherein the first optically sensitive layer is relatively completely absorbent of the light outside the at least one first wavelength interval.
4. The photodetector of claim 3 , wherein the first optically sensitive layer is relatively completely absorbent of light in the first wavelength interval.
5. The photodetector of claim 1 , wherein each of the optically sensitive layers comprises nanocrystals of a material having a bulk bandgap of less than approximately 0.5 eV.
6. The photodetector of claim 5 , wherein the nanocrystals of at least one optically sensitive layer are quantum confined to a bandgap corresponding to 490 nm wavelength.
7. The photodetector of claim 5 , wherein the nanocrystals of at least one optically sensitive layer are quantum confined to a bandgap of approximately 2.5 eV.
8. The photodetector of claim 5 , wherein the nanocrystals of at least one optically sensitive layer are quantum confined to a bandgap corresponding to 560 nm wavelength.
9. The photodetector of claim 5 , wherein the nanocrystals of at least one optically sensitive layer are quantum confined to a bandgap of approximately 2.2 eV.
10. The photodetector of claim 5 , wherein the nanocrystals of at least one optically sensitive layer are quantum confined to a bandgap of approximately 1.8 eV.
11. The photodetector of claim 5 , wherein the nanocrystals of at least one optically sensitive layer are quantum confined to a bandgap of approximately 1.2 eV.
12. The photodetector of claim 5 , wherein the nanocrystals of at least one optically sensitive layer are quantum confined to a bandgap of approximately 0.9 eV.
13. The photodetector of claim 5 , wherein the nanocrystals of at least one optically sensitive layer are quantum confined to a bandgap of approximately 0.7 eV.
14. The photodetector of claim 5 , wherein the nanocrystals of at least one optically sensitive layer are quantum confined to a bandgap corresponding to 630 nm wavelength.
15. The photodetector of claim 5 , wherein the nanocrystals of at least one optically sensitive layer are quantum confined to a bandgap corresponding to 650 nm wavelength.
16. The photodetector of claim 5 , wherein the nanocrystals of at least one optically sensitive layer are quantum confined to a bandgap corresponding to 670 nm wavelength.
17. The photodetector of claim 5 , wherein the nanocrystals of at least one optically sensitive layer are quantum confined to a bandgap corresponding to 700 nm wavelength.
18. The photodetector of claim 5 , wherein the nanocrystals of at least one optically sensitive layer are quantum confined to a bandgap corresponding to 800 nm wavelength.
19. The photodetector of claim 5 , wherein the nanocrystals of at least one optically sensitive layer are quantum confined to a bandgap corresponding to 900 nm wavelength.
20. The photodetector of claim 5 , wherein the nanocrystals of at least one optically sensitive layer are quantum confined to a bandgap corresponding to 1000 nm wavelength.
21. The photodetector of claim 5 , wherein the nanocrystals of at least one optically sensitive layer are quantum confined to a bandgap corresponding to 1300 nm wavelength.
22. The photodetector of claim 5 , wherein the nanocrystals of at least one optically sensitive layer are quantum confined to a bandgap corresponding to 1650 nm wavelength.
23. The photodetector of claim 5 , wherein the nanocrystals of at least one optically sensitive layer are quantum confined to a bandgap corresponding to 3 um wavelength.
24. The photodetector of claim 5 , wherein the nanocrystals of at least one optically sensitive layer are quantum confined to a bandgap corresponding to 5 um wavelength.
25. The photodetector of claim 1 , wherein an optical sensitivity of at least one optically sensitive layer is at an intensity of light less than approximately 1 lux is more than twice the optical sensitivity of the optically sensitive material at an intensity of light of at least 100 lux.
26. The photodetector of claim 1 , wherein the optical sensitivity of at least one optically sensitive layer at an intensity of light less than approximately 1 lux is more than ten times the optical sensitivity of the optically sensitive material at an intensity of light of at least 100 lux.
27. The photodetector of claim 1 , wherein the optical sensitivity of at least one optically sensitive layer is more than 1000 mV/lux-s at relatively low light levels and less than 500 mV/lux-s at relatively high light levels.
28. The photodetector of claim 1 , wherein the optical sensitivity of at least one optically sensitive layer is more than 2000 mV/lux-s at relatively low light levels and less than 400 mV/lux-s at relatively high light levels.
29. The photodetector of claim 1 , wherein the optical sensitivity of at least one optically sensitive layer is more than 3000 mV/lux-s at relatively low light levels and less than 300 mV/lux-s at relatively high light levels.
30. The photodetector of claim 1 , wherein the first optically sensitive layer comprises a first material having a first thickness, and the combination of the first material and the first thickness provides a first responsivity to light of a first wavelength, wherein the second optically sensitive layer comprises a second material having a second thickness, and the combination of the second material and the second thickness provides a second responsivity to light of a second wavelength, wherein the first responsivity and the second responsivity are approximately equal.
31. The photodetector of claim 1 , wherein the first optically sensitive layer comprises a first material having a first thickness, and the combination of the first material and the first thickness provides a first photoconductive gain to light of a first wavelength, wherein the second optically sensitive layer comprises a second material having a second thickness, and the combination of the second material and the second thickness provides a second photoconductive gain to light of a second wavelength.
32. The photodetector of claim 31 , wherein the first photoconductive gain and the second photoconductive gain are approximately equal.
33. The photodetector of claim 1 , wherein the first optically sensitive layer comprises a first material having a first thickness, and the combination of the first material and the first thickness provides a first absorbance to light of a first wavelength, wherein the second optically sensitive layer comprises a second material having a second thickness, and the combination of the second material and the second thickness provides a second absorbance to light of a second wavelength, wherein the first absorbance and the second absorbance are approximately equal.
34. The photodetector of claim 1 , wherein persistence of each of the optically sensitive layers is approximately equal.
35. The photodetector of claim 1 , wherein persistence of each of the optically sensitive layers is approximately in a range of 1 ms to 200 ms.
36. The photodetector of claim 1 , wherein the first optically sensitive layer comprises a nanocrystal material having first photoconductive gain and the second optically sensitive layer comprises a nanocrystal material having a second photoconductive gain.
37. The photodetector of claim 1 , wherein at least one of the optically sensitive layers comprises a nanocrystal material having photoconductive gain and a responsivity of at least approximately 0.4 amps/volt (A/V).
38. The photodetector of claim 37 , wherein the responsivity is achieved when a bias is applied across the at least one of the optically sensitive layers, wherein the bias is approximately in a range of 1 volt to 5 volts.
39. The photodetector of claim 37 , wherein the first optically sensitive layer comprises a nanocrystal material having first photoconductive gain and a first responsivity approximately in a range of 0.4 A/V to 100 A/V.
40. The photodetector of claim 39 , wherein the second optically sensitive layer comprises a nanocrystal material having a second photoconductive gain and a second responsivity approximately in a range of 0.4 A/V to 100 A/V.
41. The photodetector of claim 40 , wherein the second photoconductive gain is greater than the first photoconductive gain.
42. The photodetector of claim 1 , wherein at least one of the optically sensitive layers includes nanocrystals comprising nanoparticles.
43. The photodetector of claim 42 , wherein the nanocrystals are quantum confined to have an effective bandgap more than twice the bulk bandgap.
44. he photodetector of claim 42 , wherein a nanoparticle diameter of the nanoparticles is less than a Bohr exciton radius of bound electron-hole pairs within the nanoparticle.
45. The photodetector of claim 42 , wherein a first diameter of nanocrystals of the first optically sensitive layer is greater than a second diameter of nanocrystals of the second optically sensitive layer.
46. The photodetector of claim 42 , wherein a first diameter of nanocrystals of the first optically sensitive layer is less than a second diameter of nanocrystals of the second optically sensitive layer.
47. The photodetector of claim 42 , wherein at least one of the optically sensitive layers comprises nanocrystals of a material having a bulk bandgap of less than approximately 0.5 electronvolts (eV), and wherein the nanocrytals are quantum confined to have a bandgap more than 1.0 eV.
48. The photodetector of claim 1 , wherein the first optically sensitive layer comprises a first composition including one of lead sulfide (PbS), lead selenide (PbSe), lead tellurium sulfide (PbTe), indium phosphide (InP), indium arsenide (InAs), and germanium (Ge).
49. The photodetector of claim 1 , wherein the second optically sensitive layer comprises a second composition including one of indium sulfide (In 2 S 3 ), indium selenide (In 2 Se 3 ), indium tellurium (In 2 Te 3 ), bismuth sulfide (Bi 2 S 3 ), bismuth selenide (Bi 2 Se 3 ), bismuth tellurium (Bi 2 Te 3 ), indium phosphide (InP), gallium arsenide (GaAs), silicon (Si), and germanium (Ge).
50. The photodetector of claim 1 , wherein each of the optically sensitive layers comprises different compound semiconductor nanocrystals, wherein the first optically sensitive layer comprises a composition including lead and the second optically sensitive layer comprises a composition including one of indium and bismuth.
51. The photodetector of claim 1 , wherein at least one of the optically sensitive layers comprises monodisperse nanocrystals.
52. The photodetector of claim 1 , wherein each of the optically sensitive layers comprises nanocrystals of different materials.
53. The photodetector of claim 1 , wherein the first optically sensitive layer includes a first material having a first bulk bandgap and the second optically sensitive layer includes a second material having a second bulk bandgap.
54. The photodetector of claim 1 , wherein at least one of the optically sensitive layers comprises nanocrystals comprising colloidal quantum dots.
55. The photodetector of claim 54 , wherein the quantum dots include a first carrier type and a second carrier type, wherein the first carrier type is a flowing carrier and the second carrier type is one of a substantially blocked carrier and a trapped carrier.
56. The photodetector of claim 55 , wherein the colloidal quantum dots include organic ligands, wherein a flow of at least one of the first carrier type and the second carrier type is related to the organic ligands.
57. The photodetector of claim 1 , wherein at least one optically sensitive layers comprises a continuous film of interconnected nanocrystal particles in contact with the respective first electrode and the respective second electrode.
58. The photodetector of claim 57 , wherein the nanocrystal particles comprise a plurality of nanocrystal cores and a shell over the plurality of nanocrystal cores.
59. The photodetector of claim 58 , wherein the plurality of nanocrystal cores are fused.
60. The photodetector of claim 58 , wherein a physical proximity of the nanocrystal cores of adjacent nanocrystal particles provides electrical communication between the adjacent nanocrystal particles.
61. The photodetector of claim 60 , wherein the physical proximity includes a separation distance of less than approximately 0.5 nm.
62. The photodetector of claim 60 , wherein the electrical communication includes a hole mobility of at least approximately 1E-5 square centimeter per volt-second across the nanocrystal particles.
63. The photodetector of claim 58 , wherein the plurality of nanocrystal cores are electrically interconnected with linker molecules.
64. The photodetector of claim 1 , wherein at least one of the optically sensitive layers comprises a unipolar photoconductive layer including a first carrier type and a second carrier type, wherein a first mobility of the first carrier type is higher than a second mobility of the second carrier type.
65. A photodetector comprising:
an integrated circuit; and
at least two optically sensitive layers, a first optically sensitive layer and a second optically sensitive layer, the first optically sensitive layer over at least a portion of the integrated circuit and the second optically sensitive layer over the first optically sensitive layer;
wherein each optically sensitive layer is interposed between two electrodes, the electrodes including a respective first electrode and a respective second electrode;
wherein the integrated circuit selectively applies a bias to the electrodes and reads signals from the optically sensitive layers, wherein the signal is related to the number of photons received by the respective optically sensitive layer; and
wherein the first optically sensitive layer comprises a nanocrystal material having an absorption onset at a first wavelength and the second optically sensitive layer comprises a nanocrystal material having an absorption onset at a second wavelength, wherein the first wavelength is shorter than the second wavelength, and a local absorption maximum is absent from an absorption spectrum of at least one of the first optically sensitive layer and the second optically sensitive layer.