Controlled p-Type Doping of Pyrite FeS2

Bryan Voigt, Lis Stolik Valor, William Moore, Jeff Jeremiason, James Kakalios, Eray S. Aydil, Chris Leighton

Research output: Contribution to journalArticlepeer-review


Pyrite FeS2 has extraordinary potential as a low-cost, nontoxic, sustainable photovoltaic but has underperformed dramatically in prior solar cells. The latter devices focus on heterojunction designs, which are now understood to suffer from problems associated with FeS2 surfaces. Simpler homojunction cells thus become appealing but have not been fabricated due to the historical inability to understand and control doping in pyrite. While recent advances have put S-vacancy and Co-based n-doping of FeS2 on a firm footing, unequivocal evidence for bulk p-doping remains elusive. Here, we demonstrate the first unambiguous and controlled p-type transport in FeS2 single crystals doped with phosphorus (P) during chemical vapor transport growth. P doping is found to be possible up to at least ∼100 ppm, inducing ∼1018 holes/cm3 at 300 K, while leaving the crystal structure and quality unchanged. As the P doping is increased in crystals natively n-doped with S vacancies, the majority carrier type inverts from n to p near ∼25 and ∼55 ppm P, as detected by Seebeck and Hall effects, respectively. Detailed temperature- and P-doping-dependent transport measurements establish that the P acceptor level is 175 ± 10 meV above the valence band maximum, explain details of the carrier inversion, elucidate the relative mobility of electrons and holes, reveal mid-gap defect levels, and unambiguously establish that the inversion to p-type occurs in the bulk and is not an artifact of hopping conduction. Such controlled bulk p-doping opens the door to pyrite p-n homojunctions, unveiling new opportunities for solar cells based on this extraordinary semiconductor.

Original languageEnglish (US)
Pages (from-to)28258-28266
Number of pages9
JournalACS Applied Materials and Interfaces
Issue number23
StatePublished - Jun 14 2023


  • homojunction solar cells
  • p-type doping
  • photovoltaics
  • pyrite
  • semiconductors

ASJC Scopus subject areas

  • General Materials Science


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