Effects of Electrode Materials on Photocurrents in Polyethylene Terephthalate

Abstract

A new experimental technique to confirm the photoinjection from metal electrodes (aluminum, indium, copper, silver and gold) and to determine the sign of the injected carriers is developed and applied to a polyethylene terephthalate film in the wavelength region from 400 nm to 320 nm. The dominant carriers injected are electrons for aluminum and copper, and electrons and holes for silver, at around 370 nm and 340 nm, respectively, but for the others they can not be determined due to the small photoinjection currents. These photoinjection processes are mainly controlled by the work functions of metals and insulators, but can not be explained by the work functions only, and the surface states are tentatively proposed.