Hybrid structures composed of photosynthetic system and metal nanoparticles: plasmon enhancement effect.

The efficiency of chemical energy production of a photosynthetic system can be strongly enhanced in the presence of metal nanoparticles. Two competing effects contribute to the photosystem efficiency: plasmon enhancement of photon fields inside the light-absorbing chlorophyll molecules and energy transfer from chlorophylls to metal nanoparticles. The first effect can lead to strong enhancement of light absorption by the chlorophylls, whereas the second can somewhat reduce the quantum yield of the system. This paper describes one concrete example of hybrid photosystem that incorporates a photosynthetic reaction center bound to gold and silver nanocrystals. The calculated rate of production of excited electrons inside the reaction center is strongly increased due to plasmon resonance and fast electron-hole separation. In phototransport experiments with photosynthetic reaction centers, the plasma resonance can enhance the photocurrent response. The enhancement mechanism described here can be utilized in energy-conversion devices and sensors.