Surface Dye Sensitization. I. Selenium

Abstract

Surface dye sensitization of amorphous Se has been studied. Maximum quantum efficiencies measured were in the range from 10⁻² to 10⁻¹. The dye coatings were deposited onto the surfaces from their respective methanol or benzene solutions. Five dyes were used for the sensitization: crystal violet, pinacyanole, methylene blue, phenosafranine, and nitrosobenzene. The enhanced photocurrents due to the dye coatings occured at wavelengths longer than those corresponding to the intrinsic bandgap energies of Se. The maximum enhanced response was in the range from 5500 to 7000 Å, depending on the dye. The enhanced photocurrents corresponded to injection of carriers from the surface into the bulk photoconductor, electrons for some dyes (crystal violet and pinacyanole) and holes for others (methylene blue, phenosafranine, and nitrosobenzene).