  Solid-state cooling presents an energy-efficient and environmentally friendly
alternative to traditional refrigeration technologies that rely on
thermodynamic cycles involving greenhouse gases. However, conventional caloric
effects face several challenges that impede their practical application in
refrigeration devices. Firstly, operational temperature conditions must align
closely with zero-field phase transition points; otherwise, the required
driving fields become excessively large. But phase transitions occur
infrequently near room temperature. Additionally, caloric effects typically
exhibit strong temperature dependence and are sizeable only within relatively
narrow temperature ranges. In this study, we employ first-principles simulation
methods to demonstrate that light-driven phase transitions in polar oxide
perovskites have the potential to overcome such limitations. Specifically, for
the prototypical ferroelectric KNbO$_{3}$ we illustrate the existence of giant
photocaloric effects induced by light absorption ($\Delta S_{\rm PC} \sim
100$~J~K$^{-1}$~kg$^{-1}$ and $\Delta T_{\rm PC} \sim 10$~K) across a vast
temperature range of several hundred Kelvin, encompassing room temperature.
These findings are expected to be generalizable to other materials exhibiting
similar polar behavior.
