2D Hybrid Perovskites Employing an Organic Cation Paired with a Neutral Molecule

Two-dimensional (2D) hybrid perovskites
harness the chemical
and
structural versatility of organic compounds. Here, we explore 2D perovskites
that incorporate both a first organic component, a primary ammonium
cation, and a second neutral organic module. Through the experimental
examination of 42 organic pairs with a range of functional groups
and organic backbones, we identify five crystallization scenarios
that occur upon mixing. Only one leads to the cointercalation of the
organic modules with distinct and extended interlayer spacing, which
is observed with the aid of X-ray diffraction (XRD) pattern analysis
combined with cross-sectional transmission electron microscopy (TEM)
and elemental analysis. We present a picture in which complementary
pairs, capable of forming intermolecular bonds, cocrystallize with
multiple structural arrangements. These arrangements are a function
of the ratio of organic content, annealing temperature, and substrate
surface characteristics. We highlight how noncovalent bonds, particularly
hydrogen and halogen bonding, enable the influence over the organic
sublattice in hybrid halide perovskites.