PHOTOCONDUCTIVITY IN SANDWICH CELLS WITH LANGMUIR-BLODGETT-FILMS OF PHTHALOCYANINATO-POLYSILOXANES

Charge carrier photogeneration in sandwich cells containing Lagmuir-Bl odgett multiassemblies of thoxy-tetra(octyloxy)phthalocyaninato-polysi loxane (PcPS) has been investigated with respect to the spectral respo nse and light flux dependence. The films were contacted using Au or Pt bottom electrodes and Bi or Al top electrodes. ?he gain factors showe d the largest value, close to 1%, at 325nm. The DC current-voltage cur ves of the cells with Al-electrode show rectification behavior. The re ctification ratio (forward-vers. reverse-bias current) was typically h igher than 40 for the +/-0.5V applied. Under illumination, the devices worked like photocells giving open circuit voltage -0.25V (Al-electro de negative) and a fill factor value 0.43. A mechanism of the charge c arrier photogeneration process is proposed that includes free electron generation from ionized PcPS - oxygen complexes at the Al/PcPS interf ace, electron transfer to the Al-electrode and relaxation of the Schot tky space-charge region with subsequent oxidation of the Al-electrode.