Structural and Chemical Features Giving Rise to Defect Tolerance of Binary Semiconductors

Prashun Gorai, Vladan Stevanovic, Rachel Kurchin, Tonio Buonassisi

Research output: Contribution to journalArticlepeer-review

38 Scopus Citations

Abstract

Defect tolerance, or the resilience of electronic transport properties of a crystalline material to the presence of defects, has emerged as a critical factor in the success of hybrid lead halide perovskites as photovoltaic absorbers. A key aspect of defect tolerance is the shallow character of dominant intrinsic defects. However, while qualitative heuristics to identify other defect-tolerant materials have been proposed, in particular, the presence of a partially oxidized ns2 cation such as Pb, no compelling comprehensive understanding of how these shallow defects arise has yet emerged. Using modern defect theory and defect calculations, we conduct a detailed investigation of the mechanisms and identify specific features related to the chemical composition and crystal structure that give rise to defect tolerance. We find that an ns2 cation is necessary but not sufficient to guarantee shallow cation vacancies in an s-p system, and that a compound's crystal structure can ensure shallow anion vacancies in a variety of ways. Specifically, the crystal site symmetry can enforce weak interactions between the orbitals that form the defect states, thus ensuring that those defect states are shallow. We substantiate our findings by computing defect formation energies in several known as well as hypothetical materials and conclude by discussing prospects for identifying semiconductors that satisfy these criteria.
Original languageAmerican English
Pages (from-to)5583-5592
Number of pages10
JournalChemistry of Materials
Volume30
Issue number16
DOIs
StatePublished - 2018

NREL Publication Number

  • NREL/JA-5K00-72569

Keywords

  • defects
  • electronic strucutre
  • halide perovskites
  • semiconductors

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