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Original article (peer-reviewed)

Journal Energy & Environmental Science
Title of proceedings Energy & Environmental Science
DOI 10.1039/C4EE00380B

Abstract

Thin films involving an oxide heterojunction are increasingly employed as electrodes for solar water splitting in photoelectrochemical cells. Hematite (-Fe2O3) and tungsten oxide form an attractive heterojunction for this purpose. A major limitation of this strategy is the short charge carrier diusion length in hematite. Ultra-thin lms were implemented to address this low conductivity issue. Nevertheless, such ultrathin lms do not absorb light eciently. The present study explores light trapping strategies to increase the optical path length of photons in hematite. Vesicle suspensions were developed to obtain thin lms composed of microspheroids array with a tungsten oxide core and nanometer size hematite overlayer. This bottom-up approach allows a ne control of the spheroids dimensions at the micrometric to submicrometric scale. Using the Finite Dierence Time Domain method, light propagation inside the microstructures was quantitatively simulated. The simulation results were coupled to an analysis of the photoelectrochemical response of the lms. Experiments and simulation show quantitative agreement and bring important insights in the relationship between the interaction of light with the microstructure and the photoanode performance.
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