We report on the optical properties of a CsPbBr3polycrystalline
thin film on a single grain level. A sample composed of isolated nanocrystals
(NCs) mimicking the properties of the polycrystalline thin film grains
that can be individually probed by photoluminescence spectroscopy
was prepared. These NCs were analyzed using correlative microscopy
allowing the examination of structural, chemical, and optical properties
from identical sites. Our results show that the stoichiometry of the
CsPbBr3NCs is uniform and independent of the NCs’
morphology. The photoluminescence (PL) peak emission wavelength is
slightly dependent on the dimensions of NCs, with a blue shift up
to 9 nm for the smallest analyzed NCs. The magnitude of the
blueshift is smaller than the emission line width, thus detectable
only by high-resolution PL mapping. By comparing the emission energies
obtained from the experiment and a rigorous effective mass model,
we can fully attribute the observed variations to the size-dependent
quantum confinement effect.