PHOTOELECTRIC RESPONSE FROM A STILBAZOLIUM DYE IN A LANGMUIR-BLODGETTFILM-MODIFIED SNO2 ELECTRODE

Cathodic photocurrent generation from a stilbazolium dye [(CH3)(2)NC6H 4-CH=CH-C5H4NC18H37I (SI)] in a Langmuir-Blodgett (LB) film-modified S nO2 electrode has been investigated. The action spectrum coincides ver y well with the absorption spectrum of the SI-SnO2 electrode, indicati ng that the SI aggregates in the LB film are responsible for the photo current. Factors such as the intensity of the irradiation, concentrati on of donor or acceptor in the electrolyte solution, bias voltage, pH and degree of saturation with O-2, or N-2, have been studied. The resu lts indicate that the electrons flow from the electrode through the LB him to the electrolyte solution (1 mol dm(-3) KCl). It is found that tautomerization of SI takes place in ethanol solvent under irradiation . The quantum yield is very small, but can be improved by adding acid to the solution. A possible mechanism of the tautomerization of SI and of the photocurrent generation has been proposed.