Photoelectrochemical Characterization of Ta/Ta2O5/Polypyrrole Heterojunctions

A photodeposition of polypyrrole on anodic tantalum oxide thin films was performed in both organic and aqueous media. Pyrrole was photo-oxidised on insulating tantalum oxide by irradiating the electrode with light of suitable energy. Tantalum/ tantalum oxide/ polypyrrole heterojunctions were then characterized by means of photocurrent spectroscopy. The comparison between the photoelectrochemical response of the heterojunctions fabricated in organic and aqueous media, shows that the solvent used for the photodeposition of polypyrrole influences the location of the inversion potential. This result can be attributed to the different structure of polypyrrole films, which strongly depends on the medium used for the electropolymerization.