Zero-dimensional
organic antimony halides have attracted significant
attention recently due to their structural variety, tunable optical
properties, and high luminescence efficiency. Here, a new series of
antimony bromide hybrid structures with seesaw [SbBr4]
and pyramidal [SbBr5] geometries are reported with low
band gaps and blue-light excited red emissions. Their luminescence
is attributed to self-trapped excitons with a broadband emission of
a large Stokes shift. Their photoluminescence signal is sensitive
to water molecules, with a reversible positive correlation in a relative
humidity range of 30–90%, enabling them as potential materials
for real-time, self-consistent humidity sensors.