Hybrid materials structured on the molecular scale hold the promise to realize optical properties that are drastically different from their bulk counterparts. In this talk, I will describe our recent experiments utilizing a tunable plasmonic platform where emitters are sandwiched in a sub-10-nm gap between colloidally synthesized silver nanocubes and a metal film. Utilizing dye molecules with an intrinsic long lifetime reveals spontaneous emission rate enhancements exceeding a factor of 1,000 while maintaining directional emission and high quantum efficiency. Incorporating colloidal CdSe/ZnS semiconductor quantum dots into the nanocavities enables ultrafast spontaneous emission corresponding to rates exceeding 90 GHz as well as ultrafast and efficient single photon sources. Leveraging higher-order modes of the cavity allows optical processes at multiple energies to be optimized simultaneously. We demonstrate this by enhancing both the absorption and the quantum yield in monolayer MoS<sub>2</sub> resulting in a 2,000-fold enhancement in the overall fluorescence. Furthermore, at a surface fill fraction of ~20%, the film-coupled nanocubes behave as spectrally selective perfect absorbers which can be tuned from the visible to the near-infrared. We utilize these as building blocks to realize multispectral pixel arrays and reconstruct an RGB image using plasmonic pixels which show ~10,000 different color combinations. These results are promising for future ultrafast optoelectronics, multispectral photodetectors, bio-sensing and renewable energy applications.

Film-Coupled nanocubes: From ultrafast spontaneous emission to perfect absorbers

253rd National Meeting (2017)

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