PHOTOELECTROCHEMICAL PROPERTIES OF RHODAMINE-C18 SENSITIZED P-CUSCN PHOTOELECTROCHEMICAL CELL (PEC)

Surface states in p-type Cu(I) thiocyanate (CuSCN) were detected from I-V characteristics, diffuse reflectance spectra, and photocurrent action spectra. The p-CuSCN films are sensitized by rhodamine with octadecyl-alkyl chain, and the sensitized photocurrent is observed with the visible light illumination. In spite of the surface states in p-CuSCN, the maximum photocurrent quantum efficiency (phi(max)) at lambda = 560 nm, in 1 X 10(-4) M KI + I2 solution, pH = 6, reached approximately 8.6%, where the surface dye concentration of photocathode Cu/p-CuSCN/ Dye was 1.1 x 10(14) molecules CM-2. Photocathodes were biased at -0.25 V versus AgCl/Ag to give a zero dark current. From the variation of phi values with the reduction potential of electron acceptors, the cathodic sensitization mechanism presented is further confirmed.