Rigorous substrate cleaning process for reproducible thin film hematite (alpha-Fe2O3) photoanodes

Abstract

Hematite (-Fe2O3) photoanodes are widely studied as candidates for water splitting photoelectrochemical (PEC) cells. To speed up the development of high efficiency hematite photoanodes, systematic investigations of the effect of material properties such as dopants and microstructure on PEC properties that determine the photoanode performance are crucial. Toward this end, this work presents a route for reproducible fabrication of thin film hematite photoanodes with reproducible microstructure and PEC properties. Hematite thin (50 nm) films are deposited by pulsed laser deposition from a Ti-doped (1 cation%) Fe2O3 target onto cleaned transparent conducting substrates (fluorinated tin oxide, FTO, coated glass substrates). Special attention is paid to rigorous cleaning of the substrates prior to the hematite deposition, which is found to be crucial for achieving highly reproducible results. Specimens prepared by this route display homogenous conformal coating with very little spread in PEC properties between different specimens, meeting the necessary prerequisite for systematic investigation of hematite photoanodes.