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

Photocurrent action spectra and current/voltage characteristics are pr esented for transparent thin films of p-type CuSCN immersed in ethanol electrolytes containing cyanine dyes. The action spectra show that th e 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 gr eater than 50%. The highest quantum efficiency measured was greater th an or equal to 80%. From the threshold oxidation potential for injecti on and the photocurrent onset potential, the valence band edge of CuSC N in ethanol/TBABF(4) is estimated to lie between 0.55 and 0.75 V vs S CE. The results suggest that CuSCN is a promising candidate material f or the hole-conducting portion of dye sensitized heterojunctions for s olar photovoltaic applications.