Parity-Forbidden Transitions and Their Impact on the Optical Absorption Properties of Lead-Free Metal Halide Perovskites and Double Perovskites.

Journal Article

Using density functional theory calculations, we analyze the optical absorption properties of lead (Pb)-free metal halide perovskites (AB2+X3) and double perovskites (A2B+B3+X6) (A = Cs or monovalent organic ion, B2+ = non-Pb divalent metal, B+ = monovalent metal, B3+ = trivalent metal, X = halogen). We show that if B2+ is not Sn or Ge, Pb-free metal halide perovskites exhibit poor optical absorptions because of their indirect band gap nature. Among the nine possible types of Pb-free metal halide double perovskites, six have direct band gaps. Of these six types, four show inversion symmetry-induced parity-forbidden or weak transitions between band edges, making them not ideal for thin-film solar cell applications. Only one type of Pb-free double perovskite shows optical absorption and electronic properties suitable for solar cell applications, namely, those with B+ = In, Tl and B3+ = Sb, Bi. Our results provide important insights for designing new metal halide perovskites and double perovskites for optoelectronic applications.

Full Text

Duke Authors

Cited Authors

  • Meng, W; Wang, X; Xiao, Z; Wang, J; Mitzi, DB; Yan, Y

Published Date

  • July 2017

Published In

Volume / Issue

  • 8 / 13

Start / End Page

  • 2999 - 3007

PubMed ID

  • 28604009

Electronic International Standard Serial Number (EISSN)

  • 1948-7185

International Standard Serial Number (ISSN)

  • 1948-7185

Digital Object Identifier (DOI)

  • 10.1021/acs.jpclett.7b01042

Language

  • eng