Lead-free cesium titanium bromide double perovskite nanocrystals

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Abstract

Double perovskites are a promising family of lead-free materials that not only replace lead but also enable new optoelectronic applications beyond photovoltaics. Recently, a titanium (Ti)-based vacancy-ordered double perovskite, Cs2 TiBr6, has been reported as an example of truly sustainable and earth-abundant perovskite with controversial results in terms of photoluminescence and environmental stability. Our work looks at this material from a new perspective, i.e., at the nanoscale. We demonstrate the first colloidal synthesis of Cs2 TiX6 nanocrystals (X = Br, Cl) and observe tunable morphology and size of the nanocrystals according to the set reaction temperature. The Cs2 TiBr6 nanocrystals synthesized at 185 C show a bandgap of 1.9 eV and are relatively stable up to 8 weeks in suspensions. However, they do not display notable photoluminescence. The centrosymmetric crystal structure of Cs2 TiBr6 suggests that this material could enable third-harmonic generation (THG) responses. Indeed, we provide a clear evidence of THG signals detected by the THG microscopy technique. As only a few THG-active halide perovskite materials are known to date and they are all lead-based, our findings promote future research on Cs2 TiBr6 as well as on other lead-free double perovskites, with stronger focus on currently unexplored nonlinear optical applications.

Original languageEnglish
Article number1458
Number of pages13
JournalNanomaterials
Volume11
Issue number6
DOIs
Publication statusPublished - Jun 2021
Publication typeA1 Journal article-refereed

Keywords

  • Double perovskites
  • Lead-free halide perovskites
  • Nanocrystals
  • Nonlinear optics
  • Stability
  • Third-harmonic generation
  • Titanium (Ti)

Publication forum classification

  • Publication forum level 1

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Materials Science(all)

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