Three porphyrin derivative monolayers (C4Py, C6Py and C8Py) terminated with different chain lengths were successfully deposited on indium-tin oxide (ITO) electrodes using Langmuir-Blodgett (LB) technique, and the sensitized ITO electrodes exhibited high photocurrent values under ambient conditions. Action spectra of the photocurrent generation were coincident with the UV-Vis absorption spectra of these porphyrin LB monolayer modified electrodes, indicating that these porphyrin derivatives were responsible for photocurrent generation. The observed photocurrent strongly depended on the electron donor, electron acceptor and bias voltage, suggesting that photoinduced electron transfer should be a main mechanism of light sensitization for the photocurrent generation. The photocurrents were varied with the side chain length, and the compound C6Py with a longer chain exhibited the maximum photocurrent.

Key words: porphyrin derivative, LB film, photocurrent generation