Influence of One Specific Carbon-Carbon Bond on the Quality, Stability, and Photovoltaic Performance of Hybrid Organic-Inorganic Bismuth Iodide Materials

Matthew Beard, David Fabian, Alex Ganose, Joseph Ziller, David Scanlon, Shane Ardo

Research output: Contribution to journalArticlepeer-review

7 Scopus Citations


Hybrid organic-inorganic halide perovskites are promising materials for thin-film solar cells. However, the toxicity and instability of best-in-class lead-halide perovskite materials make them nonideal. To combat these issues, we replaced lead with bismuth and explored the sensitivity of these new lead-free materials to the valency and bonding of their cationic organic groups. Specifically, we synthesized and characterized the materials properties and photophysical properties of hexane-1,6-diammonium bismuth pentaiodide ((HDA2+)BiI5) and compared them to an analogue containing a more volatile organic group with half the number of carbon and nitrogen atoms in the form of n-propylammonium ((PA+)xBiI3+x, where 1 < x < 3). The full crystallographic structures of (HDA2+)BiI5 and (PA+)xBiI3+x were resolved by single-crystal X-ray diffraction. (HDA2+)BiI5 was shown to be pure-phase and have a one-dimensional structure, whereas (PA+)xBiI3+x was shown to be a mix of one-dimensional and zero-dimensional phases. Structures of the materials were confirmed by synchrotron X-ray diffraction of powders. Both (HDA2+)BiI5 and (PA+)xBiI3+x exhibit steady-state photoluminescence at room temperature. Density functional theory calculations of (HDA2+)BiI5 predict electronic absorption features and a ∼2 eV bandgap that are consistent with those observed experimentally. Structure-property relationships of the materials were examined, and moisture tolerance and film quality were found to be superior for dication-containing (HDA2+)BiI5 in relation to monocation-containing (PA+)xBiI3+x. We hypothesize that these trends are in part due to a molecular bridging effect enabled by the presence of the dicationic hexanediammonium groups in (HDA2+)BiI5. Solar cells fabricated using (HDA2+)BiI5 as the photoactive layer exhibited photovoltaic action while those containing (PA+)xBiI3+x did not, suggesting that organic dicationic groups are beneficial to light-absorber morphology and ultimately solar-cell performance.

Original languageAmerican English
Pages (from-to)1579-1587
Number of pages9
JournalACS Applied Energy Materials
Issue number3
StatePublished - 25 Mar 2019

Bibliographical note

Publisher Copyright:
© 2019 American Chemical Society.

NREL Publication Number

  • NREL/JA-5900-73935


  • bismuth halide
  • dications
  • hybrid organic-inorganic
  • nontoxic
  • photovoltaic
  • solar cells
  • solar fuels
  • stability


Dive into the research topics of 'Influence of One Specific Carbon-Carbon Bond on the Quality, Stability, and Photovoltaic Performance of Hybrid Organic-Inorganic Bismuth Iodide Materials'. Together they form a unique fingerprint.

Cite this