Terahertz (THz) radiation is a valuable tool to investigate
the
electronic properties of lead halide perovskites (LHPs). However,
attaining high-resolution information remains elusive, as the diffraction-limited
spatial resolution (∼300 μm) of conventional THz methods
prevents a direct analysis of microscopic effects. Here, we employ
THz scattering scanning near-field optical microscopy (THz-sSNOM)
for nanoscale imaging of cesium lead bromide (CsPbBr3)
thin films down to the single grain level at 600 GHz. Adopting a scattering
model, we are able to derive the local THz nanoscale conductivity
in a contact-free fashion. Increased THz near-field signals at CsPbBr3 grain boundaries complemented by correlative transmission
electron microscopy–energy-dispersive X-ray spectroscopy elemental
analysis point to the formation of halide vacancies (VBr) and Pb–Pb bonds, which induce charge carrier trapping and
can lead to nonradiative recombination. Our study establishes THz-sSNOM
as a powerful THz nanoscale analysis platform for thin-film semiconductors
such as LHPs.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.