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Broadband Plasmonic Photocurrent Enhancement from Photosystem I Assembled with Tailored Arrays of Au and Ag Nanodisks...

by Ravi Pamu, Benjamin J Lawrie, Bamin Khomami, Dibyendu Mukherjee
Publication Type
Journal Name
ACS Applied Nano Materials
Publication Date
Page Numbers
1209 to 1219

Plasmonic interactions of metal nanostructures with fluorophores are well-known. Our recent studies had demonstrated the proofs-of-concept for plasmon enhanced photocurrents from the multi-chromophore photosynthetic protein, Photosystem I (PSI) assembled on Ag nano-pyramids. We reported a 6-fold photocurrent enhancement in these systems, albeit with a lack of control on the specific resonance modes interacting with the PSI system. The present study investigates the spectrally-resolved photocurrents from PSI site-specifically assembled around highly ordered Au and Ag nano discs (NDs) whose dipolar plasmon resonances are tuned to the native PSI absorption at ~680 and ~560 nm respectively. We report plasmon-induced photocurrent enhancements of ~6.8 and ~17.5 at excitation wavelengths of ~680 nm and ~565 nm respectively, as compared to PSI assembled on planar ITO substrates. The action spectra for photocurrent enhancements recorded over a wavelength range of 395 - 810 nm indicate direct concurrence between the photocurrent enhancements from PSI assemblies and the plasmonic resonances for the respective ND arrays. Specifically, plasmon-induced broadband photocurrent enhancements are observed in the otherwise blind chlorophyll regions of the native PSI absorption spectrum. These intriguing findings pave the path for rational assembly of future bio-hybrid optoelectronic devices comprising natural light-harvesting antennae and plasmonic metal nanostructures.