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Polypyrrole has been photochemically deposited on different kinds of solid surfaces by illumination with sunlight; this has been interpreted as the consequence of a self-sensitited initiation process.The search for new conducting materials of a polymeric nature has led to numerous reports, especially dealing with electrochemical growth of such substances.1--3 Recently, two new methods for photo-sensitized polymerization of pyrrole using Ru(bpy)32+ and CuI(dp)*+ (5) (where bpy = bipyridine and dpp = 2,9-diphenyl-1 ,lo-phenanthroline) as sensitizers, have been published.Herein we report a direct photochemical process in which the pyrrole molecules act as photosensitizers. This simple procedure involves exposing an aqueous solution of pyrrole deposited onto a solid surface to sunlight. We chose glass, mica, and glass doped with Sn02 as the substrates for polymerization.Two types of experiments were performed. The first involved maintaining a HC104 (1 M) and pyrrole (0.5 M) suspension in water under atmospheric pressure while irradiating for around 15 h on a glass plate of approximately 3 cm2 area. A black polypyrrole film with a metallic lustre of around 100 nm thickness (measured with a Taylor Hobson Talistep) and with a conductivity of around 10-3 Q-1 cm-1 was formed.

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