Wasted photons: Photogeneration yield and charge carrier collection efficiency of hematite photoanodes for photoelectrochemical water splitting

Yifat Piekner, David S. Ellis, Daniel A. Grave, Anton Tsyganok, Avner Rothschild

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

Hematite (α-Fe2O3) is a leading photoanode candidate for photoelectrochemical water splitting. Despite extensive research efforts, the champion hematite photoanodes reported to date have achieved less than half of the maximal photocurrent predicted by its bandgap energy. Here we show that this underachievement arises, to a large extent, because of unproductive optical excitations that give rise to localized electronic transitions that do not generate electron-hole pairs. A comprehensive method for extraction of the photogeneration yield spectrum, the wavelength-dependent fraction of absorbed photons that generate electron-hole pairs, and the spatial charge carrier collection efficiency is presented, and applied for a thin (32 nm) film hematite photoanode. Its photogeneration yield is less than unity across the entire absorption range, limiting the maximal photocurrent that may be attained in an ideal hematite photoanode to about half of the theoretical limit predicted without accounting for this effect. This journal is

Original languageEnglish
Pages (from-to)4584-4598
Number of pages15
JournalEnergy and Environmental Science
Volume14
Issue number8
DOIs
StatePublished - 1 Aug 2021

ASJC Scopus subject areas

  • Environmental Chemistry
  • Renewable Energy, Sustainability and the Environment
  • Nuclear Energy and Engineering
  • Pollution

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