Investigators in the Nano/Bio Interface Center at the University of Pennsylvania have demonstrated a new mechanism for turning light into electrical current in porphyrin molecules. They fabricated an array of gold metal nanoparticles and linked them with special light-sensitive porphyrins. The plasmons at the surface of the nanoparticles focus the light to the junction where the molecules are connected. The plasmon effect increases the efficiency of current production in the molecule by a factor of 4-20 (400% to 2000%) that is then transported through the network to the outside world.
Surface plasmons are being engineered into a variety of light activated devices such as biosensors and optical circuits. This is the first time that plasmons have induced current in molecules. The action is similar to that of solar cells and may provide an approach for higher efficiency energy harvesting devices.
This research represents a collaborative effort with researchers at Duke University and the University of Maryland. Results were published in ACS Nano on January 26, 2010.
Light into Current in Molecular Arrays with Plasmons