Photoelectrochemical Behavior of Hierarchically Structured Si/WO3 Core–Shell Tandem Photoanodes
By Coridan, Robert H.; Arpin, Kevin A.; Brunschwig, Bruce S.; Braun, Paul V. & Lewis, Nathan S.
Published in Nano Letters
2014
Abstract
WO3 thin films have been deposited in a hierarchically structured core -shell morphology, with the cores consisting of an array of Si microwires and the shells consisting of a controlled morphology WO3 layer. Porosity was introduced into the WO3 outer shell by using a self-assembled microsphere colloidal crystal as a mask during the deposition of the WO3 shell. Compared to conformal, unstructured WO3 shells on Si microwires, the hierarchically structured core -shell photoanodes exhibited enhanced near-visible spectral response behavior, due to increased light absorption and reduced distances over which photogenerated carriers were collected. The use of structured substrates also improved the growth rate of microsphere-based colloidal crystals and suggests strategies for the use of colloidal materials in large-scale applications.