Suppression of the Transfer Efficiency in the Disordered LH1-RC Photosynthetic Unit

The single-photon transfer efficiency of a disordered LH1-RC complex was investigated. In contrast to uniform couplings, photon-ring coupling disorder significantly suppressed the transfer efficiency within a finite photon-detuning range, while intra-ring coupling disorder had a negligible effect. The lifetimes of the photon, ring excitation, and acceptor-site excitation were also numerically determined. It was found that the minimum in the transfer efficiency for photon-ring disorder decreased exponentially with increasing disorder strength, and was associated with the shortest lifetimes and the absence of a dark-state channel. A phonon dephasing bath decreased the transfer efficiency, except in the near-resonant detuning region where it was enhanced in the presence of photon-ring disorder.