Preparation and Band Energetics of Transparent Nanostructured SrTiO₃ Film Electrodes

Abstract

High Resolution Image Download MS PowerPoint Slide Transparent nanostructured SrTiO 3 film electrodes were fabricated on conductive substrates from SrTiO 3 nanocrystals. Band energetics were determined with spectroelectrochemical measurements, and its trap states were investigated with electrochemistry. The flat band edges ( E fb ) of nanostructured SrTiO 3 electrodes were highly dependent on the pH of the electrolyte, and measured to be −0.71, −0.96, and −1.19 V versus saturated Ag/gCl at pH 3.0, 6.8, and 13.0, respectively. The time-resolved current at different applied potentials positive of the flat band edge clearly indicate a trap-filling process. The results showed that trap state densities are also highly pH dependent. Total trap state densities of 2.0 × 10 15, 8.08 × 10 15, and 1.21 × 10 16 cm −2 were determined at pH 3.0, 6.8, and 13.0, respectively with maximum located at −0.25, −0.50, and −0.70 V. The results obtained from cyclic voltammograms are in good agreement with that obtained from the measurements of time-resolved currents. The size of the peak potentials related to the trap states (−0.25, −0.51, and −0.72 V for pH 3.0, 6.8, and 13.0, respectively) in the cyclic voltammograms increases dramatically with increase of pH, indicating that traps are mostly surface-related.