Organic photosensitive devices
The present invention generally relates to organic photosensitive optoelectronic devices. More specifically, it is directed to organic photosensitive optoelectronic devices having a photoactive organic region containing encapsulated nanoparticles that exhibit plasmon resonances. An enhancement of the incident optical field is achieved via surface plasmon polariton resonances. This enhancement increases the absorption of incident light, leading to a more efficient device.
1. A device comprising:
a first electrode;
a second electrode;
a photoactive region comprising a first donor layer and a first acceptor layer, wherein each of the first donor layer and the first acceptor layer is an organic material, disposed between and electrically connected to the first electrode and the second electrode; and
a plurality of nanoparticles consisting of a core and an insulating encapsulation layer, wherein the core is comprised of a metal, doped degenerative semiconductor or semiconductive material, said encapsulated nanoparticles dispersed within said photoactive region wherein the nanoparticles have a plasmon resonance and said photoactive region generates excitons by absorbing electromagnetic radiation when said device is exposed to electromagnetic radiation,
wherein said insulating material encapsulating the nanoparticles prevents quenching of the excitons at the nanoparticles.
2. The device of claim 1 wherein the nanoparticles are encapsulated within an oxide.
3. The device of claim 1 wherein the photoactive region comprises a first subcell, the first subcell comprising:
the first donor layer; and
the first acceptor layer in direct physical contact with the first donor layer.
4. The device of claim 3 wherein the photoactive region further comprises a second subcell, the second subcell further comprising:
a second donor layer; and
a second acceptor layer in direct physical contact with the first donor layer, wherein the second subcell is disposed between the first subcell and the second electrode.
5. The device of claim 3 wherein the nanoparticles are disposed within the first acceptor layer and the first donor layer.
6. The device of claim 4 wherein the nanoparticles are disposed between the first subcell and the second subcell.
7. The device of claim 1 wherein the nanoparticles are non-spherical.
8. The device of claim 7 wherein the photoactive region is planar thereby defining a plane, and the non-spherical nanoparticles having a longest axis and a shortest axis wherein the longest axis of each non-spherical nanoparticle is about parallel to the plane.
9. The device of claim 7 wherein each of the non-spherical nanoparticles has an axial ratio not less than about 0.1.
10. The device of claim 1 wherein an average surface-to-surface separation between nanoparticles is not greater than about 300 Å.
11. The device of claim 8 wherein the shortest axis of each non-spherical nanoparticle is not greater than about 300 Å.
12. The device of claim 2 wherein the thickness of the insulating material is not less than about 10 Å.
13. The device of claim 2 wherein the thickness of the insulating material is not greater than about 100 Å.
14. The device of claim 1 wherein the metal is Ag.
15. The device of claim 1 wherein the metal is Au.
16. The device of claim 1 wherein the metal is Cu.
17. The device of claim 1 wherein the photoactive region comprises a bulk heterojunction.
18. The device of claim 1 wherein the photoactive region comprises a dye-sensitized material.
19. A device comprising:
a first electrode;
a second electrode;
an active zone disposed between and electrically connected to the first electrode and the second electrode, the active zone comprising:
a photoactive region disposed within the active zone and disposed between and electrically connected to the first electrode and the second electrode, said photoactive region comprising a first donor layer and a first acceptor layer, wherein each of the first donor layer and the first acceptor layer is an organic material; and
additional organic materials disposed within 100 Å of the photoactive region; and
a plurality of nanoparticles consisting of a core and an insulating encapsulation layer, wherein the core is comprised of a metal, doped degenerative semiconductor or semiconductive material, said encapsulated nanoparticles dispersed within said photoactive region,
wherein the nanoparticles have a plasmon resonance and said photoactive region generates excitons by absorbing electromagnetic radiation when said device is exposed to electromagnetic radiation and said insulating material encapsulating the nanoparticles prevent quenching of the excitons at the nanoparticles.
20. The device of claim 19 , wherein the active zone further comprises an organic exciton blocking layer disposed adjacent to the photoactive region.
21. A method for fabricating a device, comprising:
obtaining nanoparticles consisting of a core and an insulating encapsulation layer, wherein the core is comprised of a metal, doped degenerative semiconductor or semiconductive material;
fabricating a first electrode;
fabricating an organic photoactive region comprising a first donor layer and a first acceptor layer; and
fabricating a second electrode, wherein each of the first donor layer and the first acceptor layer is an organic photoactive material disposed between and electrically connected to the first electrode and the second electrode, wherein the encapsulated nanoparticles are dispersed within said photoactive region.
22. The method of claim 21 , further comprising a method of depositing the photoactive region by a solution process, wherein the nanoparticles are dispersed within the solution comprising the organic photoactive materials.
23. The method of claim 21 , wherein the encapsulated particles are co-deposited with the organic photoactive material by evaporation.