Device including quantum dots
A method of making a device comprises forming a layer comprising quantum dots over a substrate including a first electrode, fixing the layer comprising quantum dots formed over the substrate, and exposing at least a portion of, and preferably all, exposed surfaces of the fixed layer comprising quantum dots to small molecules. The layer comprising quantum dots can be preferably fixed in the absence or substantial absence of oxygen. Also disclosed is a method of making a device comprises forming a layer comprising quantum dots over a substrate including a first electrode, exposing the layer comprising quantum dots to small molecules and light flux. Also disclosed is a method of making a film including a layer comprising quantum dots, the method comprising forming a layer comprising quantum dots over a carrier substrate, fixing the layer comprising quantum dots formed over the carrier substrate, and exposing at least a portion of, and preferably all, exposed surfaces of the fixed layer comprising quantum dots to small molecules. The layer comprising quantum dots can be preferably fixed in the absence or substantial absence of oxygen. Also disclosed is a method of preparing a device component including a layer comprising quantum dots, the method comprising forming a layer comprising quantum dots over a layer comprising a charge transport material, exposing the layer comprising quantum dots to small molecules and light flux. Devices, device components, and films are also disclosed.
1. A method of preparing a film including an emissive layer comprising quantum dots, the method comprising:
forming the emissive layer comprising quantum dots over a carrier substrate,
fixing the emissive layer comprising quantum dots formed over the carrier substrate, and
exposing at least a portion of exposed surfaces of the fixed emissive layer comprising quantum dots to small molecules to treat the at least a portion of the exposed quantum dot surfaces with small molecules, wherein the small molecules comprise a small polar molecule in a liquid state, and
exposing all or a portion of exposed quantum dot surfaces to light flux in the presence of the small molecules.
2. A method in accordance with claim 1 wherein the small molecule includes no more than 50 atoms.
3. A method in accordance with claim 1 wherein the small molecule has a molecular weight of less than or equal to 100 a.m.u.
4. A method in accordance with claim 1 wherein exposure to small molecules is carried out in air.
5. A method in accordance with claim 1 wherein exposure to small molecules is carried out in the absence of oxygen.
6. A method in accordance with claim 1 wherein exposure to small molecules is carried out at a temperature in a range from about 20° to about 80° C.
7. A method in accordance with claim 1 wherein the light flux includes a peak emission wavelength in a range from about 365 nm to about 480 nm.
8. A method in accordance with claim 1 wherein the light flux includes a peak emission wavelength that can excite at least a portion of the quantum dots.
9. A method in accordance with claim 1 wherein the light flux is from about 10 to about 100 mW/cm 2 .
10. A method in accordance with claim 1 wherein all or a portion of exposed surfaces of the fixed emissive layer comprising quantum dots is exposed to small molecules for at least about 30 seconds.
11. A method in accordance with claim 1 further comprising forming one or more other layers over the carrier substrate prior to forming the emissive layer comprising quantum dots.
12. A method in accordance with claim 1 further comprising forming one or more layers over the emissive layer comprising quantum dots after exposure to small molecules.
13. A method in accordance with claim 12 wherein method steps following exposure to light flux are carried out in absence of oxygen.
14. A method in accordance with claim 1 wherein the small molecules are included in a carrier medium.
15. A method in accordance with claim 1 wherein forming the emissive layer comprising quantum dots comprises applying an ink comprising quantum dots and a carrier liquid and removing the carrier liquid.
16. A method in accordance with claim 1 wherein forming the emissive layer comprising quantum dots comprises applying an ink comprising quantum dots and a carrier liquid and evaporating the carrier liquid.
17. A method in accordance with claim 1 wherein forming the emissive layer comprising quantum dots comprises applying an ink comprising quantum dots and a carrier liquid and evaporating the carrier liquid by vacuum evaporation.
18. A method in accordance with claim 1 wherein after evaporation of the liquid carrier, the emissive layer comprising quantum dots is heated in absence of oxygen to remove carrier liquid.
19. A method in accordance with claim 1 wherein exposing the emissive layer comprising quantum dots to small molecules comprises exposing the emissive layer in an atmosphere with a relative humidity from about 50% to about 85%.
20. A method in accordance with claim 1 wherein after exposure to small molecules, the emissive layer comprising quantum dots formed over the substrate is placed under vacuum of 10 −6 torr or better in absence of oxygen.