Bismuth in Lead-Tin Alloy Perovskites: Effect on Material Properties and Photovoltaic Device Performance

Jack Palmer, Jiaqi Yang, Apoorva Gupta, Connor Dolan, Bryon Larson, Sean Dunfield, Arun Mannodi-Kanakkithodi, David Fenning

Research output: Contribution to journalArticlepeer-review


Metal halide perovskites (MHPs) have a strong potential for optoelectronic applications, especially photovoltaics. A significant advantage offered by MHPs is their bandgap tunability via chemical substitution and alloying, with lead-tin alloys producing the narrowest reported bandgaps of ~1.2 eV. Efforts to further narrow the bandgap of MHPs by alloying in other elements, such as bismuth, have largely been unsuccessful due to the introduction of defective electronic states, which severely diminish electronic quality. In this study, we examine the effects of bismuth on a lead-tin alloyed MHP, motivated by the narrow bandgap of alloyed lead-tin MHPs. We find that the defect screening observed in lead-tin MHPs is not sufficient to screen the defect level introduced by bismuth, as evidenced by quenched photoluminescence, decreased mobility, and severely reduced performance in a photovoltaic device. Density functional theory calculations suggest that midgap states are introduced by bismuth addition over a range of chemical and compositional conditions. We further observe through wavelength-dependent photoconductivity that free carriers are generated out to ~0.9 eV in bismuth-containing samples, which could be of potential interest for NIR photodetection.
Original languageAmerican English
Pages (from-to)2726-2734
Number of pages9
JournalACS Applied Energy Materials
Issue number7
StatePublished - 2024

NREL Publication Number

  • NREL/JA-5900-89145


  • alloy
  • bismuth
  • defect
  • optoelectronics
  • perovskites


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