Semiconductor nanocrystals and compositions and devices including same
View Patent ↗A semiconductor nanocrystal including a core comprising a first semiconductor material comprising at least three chemical elements and a shell disposed over at least a portion of the core, the shell comprising a second semiconductor material, wherein the semiconductor nanocrystal is capable of emitting light with an improved photoluminescence quantum efficiency. Also disclosed are populations of semiconductor nanocrystals, compositions and devices including a semiconductor nanocrystal capable of emitting light with an improved photoluminescence quantum efficiency. In one embodiment, a semiconductor nanocrystal includes a core comprising a first semiconductor material comprising at least three chemical elements and a shell disposed over at least a portion of the core, the shell comprising a second semiconductor material, wherein the semiconductor nanocrystal is capable of emitting light upon excitation with a photoluminescence quantum efficiency greater than about 65%.
1. A semiconductor nanocrystal including a core comprising a first semiconductor material comprising at least three chemical elements and a shell disposed over at least a portion of the core, the shell comprising a second semiconductor material, wherein the semiconductor nanocrystal is capable of emitting light upon excitation with a photoluminescence quantum efficiency greater than about 65%.
2. A semiconductor nanocrystal in accordance with claim 1 wherein the semiconductor nanocrystal is capable of emitting light with a photoluminescence quantum efficiency greater than about 70% upon excitation.
3. A semiconductor nanocrystal in accordance with claim 1 wherein the semiconductor nanocrystal is capable of emitting light with a photoluminescence quantum efficiency greater than about 80% upon excitation.
4. A semiconductor nanocrystal in accordance with claim 1 wherein the semiconductor nanocrystal is capable of emitting light with a photoluminescence quantum efficiency greater than about 90% upon excitation.
5. A semiconductor nanocrystal in accordance with claim 1 wherein the semiconductor nanocrystal is capable of emitting light with a photoluminescence quantum efficiency greater than about 95% upon excitation.
6. A semiconductor nanocrystal in accordance with claim 1 wherein the semiconductor nanocrystal is capable of emitting light with a photoluminescence quantum efficiency of about 100% upon excitation.
7. A semiconductor nanocrystal in accordance with claim 1 wherein the first semiconductor material comprises an alloy.
8. A semiconductor nanocrystal in accordance with claim 1 wherein the first semiconductor material comprises a homogeneous alloy.
9. A semiconductor nanocrystal in accordance with claim 1 wherein the second semiconductor material comprises two or more chemical elements.
10. A semiconductor nanocrystal in accordance with claim 1 wherein the first semiconductor material comprises zinc, cadmium, and sulfur.
11. A semiconductor nanocrystal in accordance with claim 1 wherein the second semiconductor material comprises zinc and sulfur.
12. A semiconductor nanocrystal in accordance with claim 1 wherein the first semiconductor material comprises Zn x Cd 1-x S, wherein 0<x<1.
13. A semiconductor nanocrystal in accordance with claim 1 , wherein the second semiconductor material comprises ZnS.
14. A semiconductor nanocrystal in accordance with claim 12 , wherein the second semiconductor material comprises ZnS.
15. A semiconductor nanocrystal in accordance with claim 1 wherein the color of the light that can be emitted by the semiconductor nanocrystal is longer than the color of the light that can be emitted by the core without the shell.
16. A semiconductor nanocrystal in accordance with claim 1 wherein the light includes a maximum peak emission with a full width at half maximum of not more than 40 nm.
17. A semiconductor nanocrystal in accordance with claim 1 wherein the light includes a maximum peak emission with a full width at half maximum of not more than 30 nm.
18. A semiconductor nanocrystal in accordance with claim 1 wherein the light includes a maximum peak emission with a full width at half maximum of not more than 20 nm.
19. A semiconductor nanocrystal in accordance with claim 1 further including one or more ligands attached to an outer surface thereof.
20. A semiconductor nanocrystal in accordance with claim 1 wherein the shell has a thickness from greater than about 0 to about 20 monolayers.
21. A semiconductor nanocrystal in accordance with claim 1 wherein the shell has a thickness from greater than about 0 to about 10 monolayers.
22. A semiconductor nanocrystal in accordance with claim 1 wherein the shell has a thickness ranging from about 1 to about 5 monolayers.
23. A semiconductor nanocrystal in accordance with claim 1 wherein the shell has a thickness ranging from about 3 to about 5 monolayers.
24. A semiconductor nanocrystal in accordance with claim 1 wherein the second semiconductor material comprises an alloy.
25. A semiconductor nanocrystal in accordance with claim 1 wherein the second semiconductor material comprises a homogeneous alloy.
26. A semiconductor nanocrystal including a core comprising a first semiconductor material comprising at least three chemical elements and a shell disposed over at least a portion of the core, the shell comprising a second semiconductor material comprising at least three chemical elements, wherein the semiconductor nanocrystal is capable of emitting light with a photoluminescence quantum efficiency greater than about 60% upon excitation.
27. A semiconductor nanocrystal in accordance with claim 26 wherein the first semiconductor material comprises zinc, cadmium, and selenium.
28. A semiconductor nanocrystal in accordance with claim 26 wherein the second semiconductor material comprises zinc, cadmium, and sulfur.
29. A semiconductor nanocrystal in accordance with claim 26 wherein the first semiconductor material comprises Zn 1-x Cd x Se, wherein 0<x<1.
30. A semiconductor nanocrystal in accordance with claim 26 wherein the second semiconductor material comprises Cd x Zn 1-x S wherein 0<x<1.
31. A semiconductor nanocrystal in accordance with claim 29 wherein the second semiconductor material can comprise Cd x Zn 1-x S wherein 0<x<1.
32. A semiconductor nanocrystal including a core comprising a first semiconductor material comprising Zn 1-x Cd x Se, wherein 0<x<1, and a shell disposed over at least a portion of the core, the shell comprising a semiconductor material disposed over at least a portion of the nanocrystal core, wherein the shell comprises Cd x Zn 1-x S wherein 0<x<1, and is obtainable by a process comprising adding Cd-precursor, Zn-precursor, and S-precursor to a nanocrystal core and subsequently adding additional Zn-precursor and S-precursor thereto, wherein the semiconductor nanocrystal is capable of emitting light with a photoluminescence quantum efficiency greater than about 60% upon excitation.
33. A semiconductor nanocrystal including a core comprising a first semiconductor material comprising Zn 1-x Cd x Se, wherein 0<x<1, and a shell disposed over at least a portion of the core, the shell comprising a semiconductor material disposed over at least a portion of the nanocrystal core, wherein the shell comprises Cd x Zn 1-x S wherein 0<x<1, and is obtainable by a process comprising adding Cd-precursor, Zn-precursor, and S-precursor to the nanocrystal core at a temperature sufficient to initiate shell formation and subsequently adding additional Zn-precursor and S-precursor thereto to complete formation of the shell, wherein the semiconductor nanocrystal is capable of emitting light with a photoluminescence quantum efficiency greater than about 60% upon excitation.
34. A semiconductor nanocrystal in accordance with claim 33 wherein each precursor is added separately.
35. A semiconductor nanocrystal in accordance with claim 33 wherein each of the precursors is added in a periodic manner.
36. A semiconductor nanocrystal in accordance with claim 33 wherein each of the precursors is added at the same rate.