Atomic force microscope analysis of photodecomposition of pentacene film on the epitaxial thin film photocatalyst library

We have demonstrated high-throughput synthesis and screening of a thin film photocatalyst library. Pulsed laser deposition enables us to grow the thin film photocatalyst epitaxially with atomically flat terraces and steps. A binary composition spread of [(SrTiO₃) _1-x(LaAlO₃)_x] (0 < x < 1) was fabricated by a combinatorial composition gradient technique. To evaluate the photocatalytic activity for the composition spread, the photodecomposition of pentacene film on the spread was employed and was analysed quantitatively after UV illumination by using an atomic force microscope. For comparison, the photodeposition of Ag from aqueous silver nitrate solution (0.01 M) was also tested. The results obtained from the two methods were basically the same: the SrTiO₃-rich region in the film showed greater photocatalytic activity.