Ultrafast Photodynamics and Quantitative Evaluation of Biohybrid Photosynthetic Antenna and Reaction Center Complexes Generating Photocurrent
Yusuke Yoneda, Akari Goto, Takeda Nobutaka, Hiromi Harada, Masaharu Kondo, Hiroshi Miyasaka, Yutaka Nagasawa, Takehisa Dewa
Abstract
A functional linkage between light-harvesting and photocatalytic components is a pivotal issue for using solar energy in chemical conversions; however, this concept is far from being practically realized. Here, we constructed a system that integrates an artificially extended photosynthetic light-harvesting complex 2 (LH2) and a light-harvesting 1-reaction center (RC) core complex (LH1-RC). A biohybrid LH2, whose light-harvesting ability was extended by a covalently attached hydrophobic fluorophore ATTO647N (LH2-ATTO) to cover the absorption gap of LH2, was assembled with LH1-RC in a lipid bilayer. Femtosecond transient absorption spectroscopy revealed that upon an excitation of the ATTO, sequential excitation energy transfer (EET), ATTO → LH2 → LH1 → RC, was followed by a subsequent electron transfer in the RC with rates comparable to those in a native system. As a proof of concept, the functional linkage between light-harvesting and photocatalytic reactions was quantitatively demonstrated through the enhancement in the charge separation yield and photocurrent generation activity of LH2-ATTO/LH1-RC assembled on an electrode.