Plasmon-Enhanced Energy Transfer in Photosensitive Nanocrystal Device*

In this work, we fabricated and comparatively studied seven types of NC (Nanocrystal)-monolayer devices consisting of only donor, only acceptor, Au (gold) MNP (Metal Nanoparticle)-donor, Au MNP-acceptor, donor-acceptor bilayer, donor-Au MNP-acceptor trilayer, and acceptor-Au MNP-donor reverse trilayer. We experimentally and theoretically studied the effect of LSP (Localized Surface Plasmon)-enhanced FRET (Förster-type Resonance Energy Transfer) and exciton interactions from the donor NCs layer to the acceptor NCs layer. The obtained numerical results are in excellent agreement with the systematic experimental studies done in our work. Moreover, we experimentally show that LSP-enhanced FRET in these NC photosensors result in a substantially enhanced photosensitivity. For instance, compared to a single acceptor NC device, we observed a significant extension in operating wavelength range and a substantial photosensitivity enhancement (2.91-fold) around the LSP resonance peak of Au MNPs in the LSP-enhanced FRET trilayer structure.