Giant barocaloric tunability in [(CH3CH2CH2)(4)N]Cd[N(CN)(2)](3) hybrid perovskite

We report the barocaloric performance of cadmium-dicyanamide perovskite [(CH3CH2CH2)(4)N]Cd[N(CN)(2)](3) ([TPrA]Cd[dca](3)). The introduction of Cd, a large second-row post-transition metal, into this hybrid organic-inorganic perovskite structure leads to three separate thermally driven phase transitions and four polymorphs, which we characterize in full using temperature-dependent X-ray diffraction and temperature-dependent calorimetry. Amongst these transitions, the non-isochoric orthorhombic to tetragonal phase transition at high temperatures, with a large volume change of similar to 0.4%, leads to a large reversible pressure-driven isothermal change in entropy of similar to 11.5 J K-1 kg(-1), and a giant barocaloric tunability of the transition temperature with pressure of similar to 38.2 K kbar(-1), which are both desirable for future low-pressure barocaloric cooling applications.