Stationary photoconduction in thin films of a cyano-phenylamine-substituted
poly-phenylenevinylene, in both sandwich and gap arrangement, has been stu
died. In order to separate electrode from bulk effects a thin layer of SiOx
could be inserted between the indium-tinoxide (ITO) electrode and the film
. Photocurrents were measured as a function of electric field, temperature
(100 to 300K), photon energy (2.5 to 5 eV) and polarity of the applied bias
. The results indicate that for h upsilon P < 3.2 eV the photocurrent is a
superposition of bulk ionization involving relaxed singlet excitons and, de
pending on the direction of the electric field, exciton induced injection o
f predominantly electrons from the ITO. For h<upsilon> > 3.2 eV intrinsic p
hotogeneration from hot singlet excitons takes over.