Developing de novo architectures of photosynthetic complexes for the control of photocurrent output from reaction centres.

In photosynthesis, solar energy is absorbed by chlorophyll binding light-harvesting (LH) antenna complexes (1), which channel it as excitation energy towards the reaction centres (RCs), initiating a series of electron transfer reactions that allow storage of the energy in chemical form. Photosynthetic RCs operate with a quantum efficiency of 85-98%, far outstripping their artificial competitors. Thus, there is great interest in incorporating these RC's into bio-hybrid devices to generate electric current. Recently, we developed robust and low-cost techniques for micro- and nano-patterning of photosynthetic complexes onto self-assembled monolayers (SAMs) deposited on gold, glass, silicon or graphene substrates (2, 3). By using fluorescence lifetime imaging (FLIM), we have demonstrated the ability of these fabricated architectures of RCs and LH complexes to transfer excitation energy on the micron distance scale, far in excess of anything seen in nature (4), and to reversibly switch between high and low efficiency modes based on manipulation of the environmental conditions (2)