The underappreciated lone pair in halide perovskites underpins their unusual properties

Douglas H. Fabini, Ram Seshadri, Mercouri G. Kanatzidis

Research output: Contribution to journalArticlepeer-review

95 Scopus citations


The presence of 6s2 (5s2) lone-pair electrons on the B-site Pb (Sn) in all-inorganic and hybrid halide ABX3 perovskites distinguishes these materials from the familiar tetrahedral semiconductors traditionally employed in optoelectronics and is key to many of their appealing properties. These electrons are stereochemically active, albeit often in a hidden fashion, resulting in unusual and highly anharmonic lattice dynamics that are linked to many of the special optoelectronic properties displayed by this material class. This article describes the connections between this atypical electronic configuration and the electronic structure and lattice dynamics of these compounds. We illustrate how the lone pair leads to favorable bandwidths and band alignments, mobile holes, large ionic dielectric response, large positive thermal expansion, and even possibly defect-tolerant electronic transport. Taken together, the evidence suggests that other high-performing semiconductors may be found among compounds with lone-pair-bearing cations in high symmetry environments and a high degree of connectivity between atoms.

Original languageEnglish (US)
Pages (from-to)467-477
Number of pages11
JournalMRS Bulletin
Issue number6
StatePublished - Jun 1 2020

ASJC Scopus subject areas

  • General Materials Science
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry


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