Taming heat with tiny pressure.

Heat is almost everywhere. Unlike electricity, which can be easily manipulated, the current ability to control heat is still highly limited owing to spontaneous thermal dissipation imposed by the second law of thermodynamics. Optical illumination and pressure have been used to switch endothermic/exothermic responses of materials via phase transitions; however, these strategies are less cost-effective and unscalable. Here, we spectroscopically demonstrate the glassy crystal state of 2-amino-2-methyl-1,3-propanediol (AMP) to realize an affordable, easily manageable approach for thermal energy recycling. The supercooled state of AMP is so sensitive to pressure that even several megapascals can induce crystallization to the ordered crystal, resulting in a substantial temperature increase of 48 K within 20 s. Furthermore, we demonstrate a proof-of-concept device capable of programable heating with an extremely high work-to-heat conversion efficiency of ∼383. Such delicate and efficient tuning of heat may remarkably facilitate rational utilization of waste heat.