Optimizing optical absorption of Ti O2 by alloying with Ti S2

Naoto Umezawa, Anderson Janotti, Patrick Rinke, Toyohiro Chikyow, Chris G. Van De Walle

Research output: Contribution to journalArticlepeer-review

26 Citations (Scopus)


Ti O2 is an attractive material for photocatalytic water splitting, but its band gap is too large to allow for efficient absorption of solar photons. We present a comprehensive first-principles investigation of band-structure modifications induced by alloying Ti O2 with Ti S2. The band gap of Ti O2 (1-x) S2x alloys exhibits a dramatic decrease upon addition of even a low concentration of S. The optical absorption of visible light is attainable with sulfur concentrations less than x=0.25. We have verified that the band alignment in these alloys is favorable for photocatalytic applications: in particular, the conduction band exhibits only small shifts, while the majority of the band-gap change is due to an upward shift of the valence band.

Original languageEnglish
Article number041104
JournalApplied Physics Letters
Issue number4
Publication statusPublished - 2008
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)


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