Photosystem I (PSI) is one of the primary macromolecular machines that drive photosynthesis in green plants and cyanobacteria. Extracted PSI has been employed successfully as a macromolecular photosensitizer within a host of low-cost electrochemical and solid-state photovoltaic architectures. Over the course of the last ten years, our group has worked on the electrochemical interfaces to incorporate photosystem I in applied photosynthetic systems, and has created a wealth of new approaches in terms of both solid photovoltaic cells, liquid photoelectrochemical cells, and hydrogen fuel generation. These approaches have resulted in numerous publications. Using photosystem I as the key active component, we have been leading an effort to integrate PSI into biomimetic photoelectrochemical cells and devices. For example, we developed a completely organic, transparent, conductive electrode using reduced graphene oxide (RGO) on which a multilayer of PSI could be deposited.

This presentation will also explore our group’s recent efforts to integrate PSI with advanced materials, including the conducting polymers polyaniline (PANI), polypyrrole, polyviologens, and poly(3,4-ethylenedioxythiophene). These composite assemblies enhance charge shuttling processes from individual proteins within multilayer assemblies—greatly reducing charge transfer resistances and improving overall efficiency of photocells. These PSI/conducting polymer composites can be prepared by either electrochemical co-polymerization from a bath of PSI and aniline or a vapor-phase Friedel-Crafts grafting procedure. The group has reported two new prototype solid-state devices in which PSI or PSI/PANI is sandwiched between energetically appropriate electrodes. The group has also succeeded in stabilizing PSI films via crosslinking to create “wet” photoelectrochemical cells with greater performance and longevity. Finally, our current work is aimed at building new prototypes using PSI in solid state interfaces for scalable solar energy conversion. Finally, the incorporation of PSI into conducting polymer frameworks holds promise for improved conductivity and orientational control in the photoactive layers in these devices.