Metal chalcogenide nanodome-graphene plasmonic substrates
Plasmonic substrates are provided which may be used in a variety of optoelectronic devices, e.g., biosensors and photodetectors. The plasmonic substrate may comprise a layer of graphene and a plurality of discrete, individual transition metal chalcogenide nanodomes distributed on a surface of the layer of graphene, each nanodome surrounded by bare graphene. Methods for making and using the plasmonic substrates are also provided.
1. A plasmonic substrate comprising a layer of graphene and a plurality of discrete, individual transition metal chalcogenide nanodomes distributed on a surface of the layer of graphene, each nanodome surrounded by bare graphene, wherein each nanodome does not comprise metal nanoparticles on its surface and the surface of the layer of graphene does not comprise metal nanoparticles, and further wherein the transition metal chalcogenide nanodomes are WS 2 nanodomes.
2. The substrate of claim 1 , wherein at least 90% of the nanodomes on the layer of graphene are discrete, individual nanodomes surrounded by bare graphene.
3. The substrate of claim 1 , wherein the plurality of transition metal chalcogenide nanodomes have an average thickness consistent with no more than 10 layers of the transition metal chalcogenide from which the plurality of transition metal chalcogenide nanodomes is formed.
4. The substrate of claim 3 , wherein the average thickness is less than 10 nm.
5. The substrate of claim 3 , wherein the plurality of transition metal chalcogenide nanodomes have an average diameter in a range of from 50 nm to 500 nm.
6. The substrate of claim 3 , wherein the plurality of transition metal chalcogenide nanodomes have an average nanodome-to-nanodome spacing in a range of from 1 nm to 300 nm.
7. The substrate of claim 3 , wherein the plurality of transition metal chalcogenide nanodomes have an average diameter in a range of from 50 nm to 500 nm and an average nanodome-to-nanodome spacing in a range of from 1 nm to 300 nm.
8. The substrate of claim 7 , wherein the average thickness is less than 10 nm.
9. An optoelectronic device comprising the substrate of claim 1 , an electrode in electrical communication with the substrate, and a counter electrode in electrical communication with the substrate and the electrode.
10. A method of forming the substrate of claim 1 , the method comprising applying a solution comprising a transition metal precursor to the surface of the layer of graphene to form a coating thereon, and annealing the coating in the presence of a chalcogen to induce self-assembly of the nanodomes.
11. The method of claim 10 , wherein the coating has a thickness of no more than 10 nm.
12. The method of claim 10 , wherein applying the solution is carried out by dip coating the layer of graphene into the solution followed by spinning to form the coating.
13. The method of claim 12 , wherein no more than two dips are used.
14. A method of using the substrate of claim 1 , the method comprising illuminating the substrate with electromagnetic radiation to excite surface plasmons at the nanodome-graphene interfaces.