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Photoinduced Conductivity of a Porphyrin−Gold Composite Nanowire

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posted on 23.04.2009, 00:00 by Dmitri S. Kilin, Kiril L. Tsemekhman, Svetlana V. Kilina, Alexander V. Balatsky, Oleg V. Prezhdo
Negatively charged phosphine groups on the backbone of DNA are known to attract gold nanoclusters from a colloid, assembling the clusters at fixed intervals. Bridging these intervals with porphyrin−dye linkers forms an infinite conducting chain, a quantum wire whose carrier mobility can be enhanced by photoexcitation. The resulting nanoassembly can be used as a gate: a wire with a controllable conductivity. The electronic structure of the porphyrin−gold wire is studied here by density functional theory, and the conductivity of the system is determined as a function of the photoexcitation energy. Photoexcitations of the dye are found to enhance the wire conductivity by orders of magnitude.