posted on 2024-02-21, 14:38authored byKepeng Song, Yingcai Fan, Wei Qin
Defects in lead halide perovskites
(LHPs) may have a
significant
impact on charge carrier separation, but the roles of the defects
are not fully understood. Here, using aberration-corrected scanning
transmission electron microscopy (STEM), different types of antiphase
boundaries (APBs) are discovered in CsPbBr3 platelets.
APBs with a displacement vector of 1/4[111] are characterized by double
layers of CsBr layers at the (110) or (001) planes, while APBs at
the (112) planes are formed through edge sharing of PbBr6 ̵octahedra. Significant lattice distortions are determined
at (001) and (110) APBs on the basis of quantitative analyses of STEM
images. Density functional theory calculations demonstrate that all
three types of APBs can induce band offsets at their valence bands
and conduction bands. The APBs are intended to promote the separation
of photogenerated charge carriers in LHPs. These findings provide
a crystal engineering technique for enhancing the optoelectronic properties
of LHPs by controlling defects.