Structural Distortion and Bandgap Increase of Two-Dimensional Perovskites Induced by Trifluoromethyl Substitution on Spacer Cations

Pei Xi Wang, Amin Morteza Najarian, Zhaomin Hao, Andrew Johnston, Oleksandr Voznyy, Sjoerd Hoogland, Edward H. Sargent*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

23 Scopus citations

Abstract

In further advancing display technologies, especially for improved blue emitters, to engineer the bandgap of promising semiconductors such as hybrid perovskites is important. Present-day methods for tuning the bandgaps of perovskites, such as the incorporation of mixed halide anions, suffer drawbacks such as phase separation and difficulty in synthesis. Here we report a new 2D lead iodide perovskite that emits in the blue spectral region. We exploit an increased angular distortion of PbI42- octahedra to widen the bandgap of 2D metal halide perovskites. We synthesized 2D lead iodide perovskites based on (4-Y-C6H4CH2NH3)2PbI4 (Y = H, F, Cl, Br, I) and substituted the halogen atoms with a -CF3 group to create (4-CF3-C6H4CH2NH3)2PbI4 compounds. We observed that the CF3-substituted material exhibited a ∼0.16 eV larger bandgap than did the halogen-substituted materials. We used X-ray diffraction and density functional theory simulations and found that the blue shift can be assigned to the angular distortion of the PbI42- lattice, a distortion traceable to repulsive intermolecular interactions between the trifluoromethyl groups on oppositely-arranged spacers. These results add a degree of freedom in tuning 2D perovskites to selected bandgaps for optoelectronic applications.

Original languageEnglish (US)
Pages (from-to)10144-10149
Number of pages6
JournalJournal of Physical Chemistry Letters
Volume11
Issue number23
DOIs
StatePublished - Dec 3 2020

ASJC Scopus subject areas

  • General Materials Science
  • Physical and Theoretical Chemistry

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