Aging effects in <i>n</i>-type semiconducting WO3 films

Abstract

Photocurrent spectra of the polycrystalline, n-type WO3 film photoanodes are shown to undergo a profound transformation following aging in a photoelectrolysis cell containing an aqueous acidic electrolyte. The observed significant improvement of the photocurrent efficiency of the WO3 photoanodes is assigned to a decrease of the initial defect concentration in the depletion layer, due to electromigration of interstitial W6+ and W5+ ions toward the semiconductor/electrolyte interface. The durable character of this modification of the photoresponse is pointed out.