Application of nanoparticles for plasmon energy extraction in organic devices
Techniques are provided for depositing a monolayer of nanoparticles over an OLED or comparable device. In combination with an enhancement layer disposed within a threshold distance of an emissive layer of the OLED, the nanoparticles may be used to provide a nanopatch antenna or otherwise improve the performance of the OLED.
1. A method comprising:
obtaining a substrate having an organic light emitting diode (OLED) disposed thereon, the OLED comprising:
an emissive layer comprising an organic emissive material, wherein the organic emissive material has a total non-radiative decay rate constant k non-rad 0 , a total radiative decay rate constant k rad 0 , a total non-radiative decay rate constant due to the enhancement layer k non-rad plasmon , and a total radiative decay rate constant due to the enhancement layer k rad plasmon ;
an enhancement layer disposed within a threshold distance of the emissive layer at which
k
rad
plasmon
k
non
-
rad
plasmon
=
k
rad
0
k
non
-
rad
0
;
and
a gap layer disposed over the enhancement layer; and
inkjet printing nanoparticles over the gap layer by ejecting the nanoparticles dispersed in a solvent from an inkjet printhead toward the OLED to form a monolayer of nanoparticles over the gap layer;
wherein the nanoparticles are dispersed in the solvent at a mass density of 1-10 mg/mL.
2. The method of claim 1 , wherein a ratio of drop size to distance between adjacent drops on the OLED is 1:1 to 3:1.
3. The method of claim 1 , wherein the drops are ejected from the inkjet printhead at a rate of 100-2000 drops per second.
4. The method of claim 1 , further comprising moving the inkjet printhead across the surface of the OLED at a speed of 10-100 mm/s.
5. The method of claim 1 , further comprising maintaining a platen on which the substrate is disposed during the step of inkjet printing the nanoparticles at a temperature of 20-100 C.
6. The method of claim 1 , wherein the solvent comprises a plurality of solvents.
7. The method of claim 1 , further comprising forming the gap layer over the top cathode prior to ejecting the nanoparticles toward the OLED.
8. The method of claim 7 , wherein the gap layer is deposited via inkjet printing.
9. The method of claim 7 , wherein the gap layer is deposited via thermal evaporation, atomic layer deposition, chemical vapor deposition, sputtering, spin coating, blade coating, drop casting, or a combination thereof.
10. The method of claim 1 , wherein the nanoparticles comprise Ag, Al, Au, Ir, Pt, Ni, Cu, W, Ta, Fe, Cr, Mg, Ga, Rh, Ti, Ru, Pd, In, Bi, Ca, or a combination thereof.
11. The method of claim 1 , wherein the nanoparticles comprise titania, silicon, silicon dioxide, silicon nitride, aluminum oxide, zinc oxide, nickel oxide, germanium oxide, lithium fluoride, zinc sulfide, zinc selenide, molybdenum oxide, or a combination thereof.
12. The method of claim 1 , wherein a plurality of OLEDs are disposed over the substrate and the method further comprises depositing nanoparticles only over selected OLEDs of the plurality of OLEDs.
13. The method of claim 12 , wherein the selected OLEDs correspond to a type of sub-pixel in a multi-pixel display.
14. The method of claim 1 , wherein the nanoparticles have a variety of shapes, sizes, and/or materials.
15. The method of claim 14 , wherein at least one of the shape, size, or material is selected based upon a type of sub-pixel over which the nanoparticles are deposited.
16. The method of claim 1 , further comprising:
depositing a patterned nanoparticle adhesion layer over the OLED prior to inkjet printing the nanoparticles.
17. The method of claim 1 , further comprising:
filtering material ejected by the inkjet printhead as the material is ejected by the inkjet printhead to remove unwanted material, to reduce nanoparticle aggregation within the solvent, or a combination thereof.
18. A consumer electronic device fabricated according to the method of claim 1 .
19. The consumer electronic device of claim 18 , wherein the device is at least one type selected from the group consisting of: a flat panel display, a curved display, a computer monitor, a medical monitor, a television, a billboard, a light for interior or exterior illumination and/or signaling, a heads-up display, a fully or partially transparent display, a flexible display, a rollable display, a foldable display, a stretchable display, a laser printer, a telephone, a cell phone, tablet, a phablet, a personal digital assistant (PDA), a wearable device, a laptop computer, a digital camera, a camcorder, a viewfinder, a micro-display that is less than 2 inches diagonal, a 3-D display, a virtual reality or augmented reality display, a vehicle, a video walls comprising multiple displays tiled together, a theater or stadium screen, and a sign.
20. A method comprising:
obtaining a substrate having an organic light emitting diode (OLED) disposed thereon, the OLED comprising:
an emissive layer comprising an organic emissive material, wherein the organic emissive material has a total non-radiative decay rate constant k non-rad 0 , a total radiative decay rate constant k rad 0 , a total non-radiative decay rate constant due to the enhancement layer k non-rad plasmon , and a total radiative decay rate constant due to the enhancement layer k rad plasmon ;
an enhancement layer disposed within a threshold distance of the emissive layer at which
k
rad
plasmon
k
non
-
rad
plasmon
=
k
rad
0
k
non
-
rad
0
;
and
a gap layer disposed over the enhancement layer;
inkjet printing nanoparticles over the gap layer by ejecting the nanoparticles dispersed in a solvent from an inkjet printhead toward the OLED to form a monolayer of nanoparticles over the gap layer; and
moving the inkjet printhead across the surface of the OLED at a speed of 10-100 mm/s;
wherein a ratio of drop size to distance between adjacent drops on the OLED is 1:1 to 3:1; and
wherein the drops are ejected from the inkjet printhead at a rate of 100-2000 drops per second.