Effect of dye aggregation on the photosensitization effect of conducting polypyrrole sensitized with Prussian Blue

The effect of dye aggregation at the small concentration (0-4 mM/monomer) o f dispersed Prussian Blue (PB) on the photocurrents were studied in solid s tate cells fabricated using conducting polypyrrole (Ppy) coated electrodes sandwiched with solid polymer electrolytes viz, polyvinyl alcohol(PVA) with phosphoric acid. These exhibit good photoresponse to visible light: photoc urrents being 25 times more than that of the dark current values depending on the concentration of the sensitizer and the applied field. The sensitiza tion increases with concentration of the dye at low concentrations but at h igh concentration formation of dye aggregates (H-type) has a negative impac t on the photosensitization process. The current-voltage (I-V) characterist ics in such cells reveal that the charge transport is mainly governed by th e space charge effects and the sensitization effects are due to the lowerin g of the potential barrier formed at the Py/PVA + PB interface under photoe xcitation. (C) 2001 Elsevier Science B.V. All rights reserved.