Colossal Reversible Barocaloric Effects in Layered Hybrid Perovskite (C₁₀H₂₁NH₃)₂MnCl₄ under Low Pressure Near Room Temperature

Barocaloric effects in a layered hybrid organic–inorganic compound, (C 10 H 21 NH 3 ) 2 MnCl 4 , that are reversible and colossal under pressure changes below 0.1 GPa are reported. This barocaloric performance originates in a phase transition characterized by different features: A strong disordering of the organic chains, a very large volume change, a very large sensitivity of the transition temperature to pressure and a small hysteresis. The obtained values are unprecedented among solid‐state cooling materials at such low pressure changes and demonstrate that colossal effects can be obtained in compounds other than plastic crystals. The temperature‐pressure phase diagram displays a triple point indicating enantiotropy at high pressure.