Chain-length dependence of photoelectric conversion from a porphyrin monolayer modified electrode

The photoelectrochemistry of a series of porphyrins containing an alkyl chain terminated with imidazolyl, is described. Indium–tin oxide electrodes deposited with porphyrins using the Langmuir–Blodgett (LB) technique exhibit high photocurrent values under ambient condition. Action spectra of the photocurrent generation are coincident with the absorption of the LB film-modified electrodes, indicating that the dye aggregates in the LB film are responsible for the photocurrent. The bias voltages that may influence the photocurrent have also been investigated. The photocurrents varied with the side chain length; the compound with a longer chain but not with the shortest chain generated the maximum photocurrent. To interpret such a special case, a possible mechanism is suggested. 2002 Elsevier Science B.V. All rights reserved.