Hybrid nanomaterials are targeted by a rapidly growing group of nanooptics researchers, due to the promise of optical behavior that is difficult or even impossible to create with nanostructures of homogeneous composition. Examples of important areas of interest include coherent coupling, Fano resonances, optical gain, solar energy conversion, photocatalysis, and nonlinear optical interactions. In addition to the coupling interactions, the strong dependence of optical resonances and damping on the size, shape, and composition of the building blocks provides promise that the coupling interactions of hybrid nanomaterials can be controlled and manipulated for a desired outcome. Great challenges remain in reliably synthesizing and characterizing hybrid nanomaterials for nanooptics.
We review and describe the synthesis, characterization, and applications of new hybrid plasmonic nanomaterials that are created through plasmon-induced photopolymerization. Involved polymer can contain active species, resulting in advanced hybrid nano-emitters
The work is placed within the broader context of hybrid nanomaterials involving plasmonic metal nanoparticles and molecular materials placed within the length scale of the evanescent field from the metal surface. We specifically review three important applications of free radical photopolymerization to create hybrid nanoparticles: local field probing, photoinduced synthesis of advanced hybrid nanoparticles (including light-emitting nanosystems), and nanophotochemistry.
We first demonstrate that nanoscale photopolymerization is possible at the surface of Ag nanoparticles,1,2 gold nanocubes3 and within the gap between two coupled metal nanoparticles.4 This local polymer integration enables symmetry breaking, quantification of plasmonic near-fields and trapping of molecules whose Raman signature gets amplified.
Secondly, we show that it is possible to integrate quantum nanoemitters in the vicinity of plasmonic nanostructures with high spatial precision via two-photon polymerization. 5 In particular, we demonstrate two-color nanoemitters that enable the selection of the dominant emitting wavelength by varying the polarization of excitation light. The nanoemitters were fabricated by using two polymerizable solutions with different quantum dots, emitters of different colors can be positioned selectively in different orientations in the close vicinity of the metal nanoparticles. The dominant emission wavelength of the metal/polymer anisotropic hybrid nanoemitter thus can be selected by altering the incident polarization.
1. Phys. Rev. Lett. 98, 107402 (2007)
2. ACS Nano 4, 4579 (2010)
3. J. Phys. Chem C. 116, 24734 (2012)
4. ACS Photonics 2, 121 (2015)
5. Nano Letters 15, 7458 (2015)