  Highly efficient anti-Stokes (AS) photoluminescence (PL) is observed from
halide perovskite quantum dots (QDs) due to their strong electron-phonon
interactions. The AS PL is particularly intriguing as it suggests the potential
for semiconductor optical cooling if the external quantum efficiency approaches
100%. However, the PL quantum efficiency in QDs is primarily dominated by
multiparticle nonradiative Auger recombination processes under intense
photoexcitation, which impose limits on the optical cooling gain. Here, we
investigate the Auger recombination of dot-in-crystal perovskites. We
quantitatively estimate the maximum optical cooling gain and the corresponding
excitation intensity. We further conducted optical cooling experiments and
demonstrate a maximum photo-cooling of approximately 9 K from room temperature.
Additionally, we confirmed that increasing the excitation intensity leads to a
transition from photo-cooling to photo-heating. These observations are
consistent with our time-resolved measurements, offering insights into the
potential and limitations of optical cooling in semiconductor QDs.
