(735c) Plasmon Induced Photocurrent of Photosystem I Assembled on Metal Nanostructures

Photosystem I (PS I), the photosynthetic membrane protein, undergoes light activated charge separation and unidirectional electron transfer with near-unity quantum efficiency. The robust photoelectrochemical activities of PSI make it an ideal biomaterial for bio-hybrid photovoltaic and/or, optoelectronic devices. But, the first step towards rational design of such devices requires systematic electrochemical characterizations of PSI assembly in tailored biotic-abiotic interfaces. In the past, such interfaces have been created using plasmonic metal nanostructures to tune optoelectronic properties of single molecule fluorophores. Based on our recent works, we present the first-ever experimental verification of plasmon-induced photocurrent enhancements of multi-chromophore PSI complex. The excitation wavelength depended plasmon enhanced photocurrents indicate that blue light excitation is more efficient than red light excitation which can be explained by previously reported observations of excessive plasmon-induced fluorescence emission losses from PSI in red region of the excitation wavelengths. Based on these results, our on-going efforts are directed towards the systematic investigation of the effect of varying plasmon peak positions tuned with designer nanopatterns on the plasmon-enhanced photocurrents from PSI assembly on these structures. We study the role of tailored Al nanopatterned substrates designed with E-beam lithography for specific peak plasmonic resonance peaks and plasmon-induced photocurrent action spectra from PSI complexes. The FDTD simulations for localized plasmon resonance electric field distributions along with experimental results will be utilized for determining accurate plasmon enhancements action spectrum. This work will shine light on the fundamental biophysics behind the alterations in excitation energy transfer mechanism among chlorophyll network in PSI under plasmon-induced localized electric field.