Photoconductivity of Self-Assembled Porphyrin Nanorods

• Published in: Nano letters Vol. 4; no. 7; pp. 1261 - 1265
• Main Authors: Schwab, Alexander D, Smith, Deirdre E, Bond-Watts, Brooks, Johnston, Danvers E, Hone, James, Johnson, Alan T, de Paula, Julio C, Smith, Walter F
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 14-07-2004
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic transport in multilayers, nanoscale materials and structures; Exact sciences and technology; Materials science; Methods of nanofabrication; Nanocrystalline materials; Physics; Self-assembly; Atomic force microscopy; Self-assembly; Energy levels; Stacking sequence; Visible radiation; Rods; Experimental study; Photoconductivity; Nanostructured materials; Nanorod; Organic compounds; Porphyrins
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl049421v

The photoconductivity of nanorods self-assembled from meso-tetrakis(4-sulfonatophenyl)porphine is described. The nanorods are insulating in the dark. Upon illumination with 488 nm light, the nanorods become photoconductive, exhibiting a rapid turn on/off (<100 ms) of the current when the light is turned on/off. This photoconductivity grows over hundreds of seconds with light exposure and decays slowly when the light is off. The nanorods can be trained via an applied bias to exhibit a short-circuit photocurrent (with corresponding open-circuit photovoltage) that flows in the direction opposite that of the training bias. A qualitative model is proposed, in which conduction occurs through the tightly coupled LUMOs of close-packed porphyrin molecules.