EFFICIENT PHOTO-HOLE INJECTION FROM ADSORBED CYANINE DYES INTO ELECTRODEPOSITED COPPER(I) THIOCYANATE THIN-FILMS

Photocurrent action spectra and current/voltage characteristics are presented for transparent thin films of p-type CuSCN immersed in ethanol electrolytes containing cyanine dyes. The action spectra show that the photocurrent is caused by hole injection from adsorbed dyes. Of the dyes tested, those with oxidation potentials greater than or equal to 0.7 V vs SCE photoinject holes into CuSCN with quantum efficiencies greater than 50%. The highest quantum efficiency measured was greater than or equal to 80%. From the threshold oxidation potential for injection and the photocurrent onset potential, the valence band edge of CuSCN in ethanol/TBABF(4) is estimated to lie between 0.55 and 0.75 V vs SCE. The results suggest that CuSCN is a promising candidate material for the hole-conducting portion of dye sensitized heterojunctions for solar photovoltaic applications.