Solid-state compositions and methods for generating white light
View Patent ↗This application discloses a new family of inorganic-organic hybrid semiconductor bulk materials built on periodic nanostructured 2D layers of ZnS that emit bright white light with high quantum efficiency. These ZnS-based crystalline inorganic-organic hybrid semiconductors have well defined and precisely controllable crystal structure and composition. Their optical emission properties, including intensity, quantum yield, and color quality, can be systematically tuned by varying the composition of both inorganic and organic components. Methods for preparing these materials, use of these materials as a new type of single-phased white light emitting phosphors, and their applications in making WLED devices are also disclosed.
1. An inorganic-organic hybrid semiconductor material capable of emitting white light, the material comprising a crystalline structure formed from a repeating unit, the repeating unit comprising a two-dimensional semiconducting inorganic double layer of a II-VI chalcogenide compound, wherein two opposite sides of the double layer are each attached to a layer of an organic ligand, wherein the II-VI chalcogenide compound is characterized by formula [M 2(1-x) N 2x Y 2(1-y) Z 2y ], said material optionally doped with Manganese (Mn) in the range of about 0.01 to 0.5 mol %, wherein:
M is Zn;
N is Cd;
Y and Z are each independently selected from the group consisting of S, Se and Te;
x is a fractional number between 0.05 and 0.3, inclusive; and
y is 0, 1, or a fractional number between 0 and 1.
2. The inorganic-organic hybrid semiconductor material of claim 1 , characterized by formula [M 2(1-x) N x Y 2(1-y) Z 2y (L)], wherein:
M is Zn;
N is Cd;
Y and Z are each independently selected from the group consisting of S, Se and Te; and
L is an organic ligand.
3. The inorganic-organic hybrid semiconductor material of claim 2 , wherein y is 0, further characterized by formula [M 2(1-x) N 2x Y 2 (L)], wherein:
M is Zn;
N is Cd;
Y is selected from the group consisting of S, Se and Te;
x is a fractional number between 0.05 and 0.3, inclusive; and
y is a fractional number between 0 and 0.15.
4. The inorganic-organic hybrid semiconductor material of claim 2 , further characterized by formula [Zn 2(1-x) Cd x S 2(1-y) Se 2y (L)].
5. The inorganic-organic hybrid semiconductor material according to claim 2 , wherein L is an organic ligand capable of coordinating to Zn and/or Cd to form an orderly layered structure.
6. The inorganic-organic hybrid semiconductor material according to claim 1 , doped with a Mn in the range of about 0.01 to 0.2 mol %.
7. The inorganic-organic hybrid semiconductor material of claim 6 , wherein said small amount is in the range of about 0.08 mol %.
8. The inorganic-organic hybrid semiconductor material according to claim 1 , wherein said white light emitted has CIE-1931 coordinates x and y both in the range of about 0.28 to 0.35 or has CIE-1976 coordinate u′ is in the range of about 0.15-0.25 and coordinate v′ in the range of about 0.40-0.50.
9. The inorganic-organic hybrid semiconductor material according to claim 1 , wherein the photoluminescence quantum yield (PLQY) of the semiconductor material is at least about 15%.
10. The inorganic-organic hybrid semiconductor material according to claim 1 , wherein the photoluminescence quantum yield (PLQY) of the semiconductor material is in the range of about 15 to about 40%.
11. The inorganic-organic hybrid semiconductor material of claim 1 , characterized by a formula selected from the group consisting of Zn 1.9 Cd 0.1 S 2 (L), Zn 1.8 Cd 0.2 S 2 (L), Zn 1.7 Cd 0.3 S 2 (L), Zn 1.6 Cd 0.4 S 2 (L), Zn 1.5 Cd 0.5 S 2 (L), Zn 1.9 Cd 0.1 S 1.9 Se 0.1 (L), Zn 1.8 Cd 0.2 S 1.9 Se 0.1 (L), Zn 1.7 Cd 0.3 S 1.9 Se 0.1 (L), Zn 1.6 Cd 0.4 S 1.9 Se 0.1 (L), Zn 1.5 Cd 0.5 S 1.9 Se 0.1 (L), Zn 1.9 Cd 0.1 S 1.8 Se 0.2 (L), Zn 1.7 Cd 0.3 S 1.8 Se 0.2 (L), Zn 1.6 Cd 0.4 S 1.8 Se 0.2 (L), Zn 1.5 Cd 0.5 S 1.8 Se 0.2 (L), Zn 1.9 Cd 0.1 S 1.7 Se 0.3 (L), Zn 1.7 Cd 0.3 S 1.7 Se 0.3 (L), Zn 1.6 Cd 0.4 S 1.7 Se 0.3 (L), and Zn 1.5 Cd 0.5 S 1.7 Se 0.3 (L), wherein L at each occurrence is independently selected from propylamine, butylamine, hexylamine, and octylamine.
12. The inorganic-organic hybrid semiconductor material of claim 11 , further doped by Mn in an amount in the range of about 0.01 mol % to about 0.2 mol % based on each respective formula.
13. A composition comprising an inorganic-organic hybrid semiconductor material according to claim 1 .
14. A method for preparing an inorganic-organic hybrid semiconductor material characterized by formula [M 2(1-x) N x Y 2(1-y) Z 2y (L)], the method comprising a one-pot solvothermal reaction, wherein:
M is Zn;
N is Cd;
Y and Z are each independently selected from the group consisting of S, Se and Te;
x is a fractional number between 0.05 and 0.3, inclusive; and
y is 0, 1, or a fractional number between 0 and 1; and
L is an organic ligand.
15. The method of claim 14 , wherein said one-pot solvothermal reaction comprises reacting a zinc salt, a cadmium salt, and sulfur in a proper amount ratio in a solvent.
16. A semiconductor device comprising the inorganic-organic hybrid semiconductor material according to claim 1 .
17. A light-emitting device comprising the inorganic-organic hybrid semiconductor material according to claim 1 .
18. A method of making a light-emitting device capable of emitting white light, the method comprising coating an inorganic-organic hybrid semiconductor material according to claim 1 , or a composition thereof, on the device.
19. The inorganic-organic hybrid semiconductor material according to claim 2 , wherein L is an organic ligand capable of coordinating to Zn and/or Cd to form an orderly layered structure.
20. The inorganic-organic hybrid semiconductor material according to claim 19 , wherein said organic ligand is an organic amine selected from ethylamine, propylamine, butylamine, pentylamine, hexylamine, heptylamine, octylamine, 4-picoline, 4-phenylpyridine, 4,4′-bipyridine, 1,2-bis(4-pyridyl)ethane, m-xylylenediamine, p-xylylenediamine, and aminoethylpiperazine.