Tunable barocaloric effects of two-dimensional hybrid perovskite through carbon chain lengths

Organic–inorganic hybrid perovskites have recently emerged as a promising class of barocaloric materials. The entropy change in such materials mainly originates from the order-to-disorder phase transition of the organic carbon chains. However, the influence of the carbon chain length on the barocaloric performance is rarely discussed in the literature. In this study, we report a series of hybrid perovskites, (CnH2n+1NH3)2CoCl4 (n = 8–14), in order to establish a systematic correlation between chain length and barocaloric effects. We demonstrate that the phase transition temperature (from 347 to 374 K) and entropy change (from 130 to 299 J kg−1 K−1) both increase at longer carbon chains, arising from enhanced intra- and/or inter-layer van der Waals interactions that elevate the energy barrier of the order-to-disorder phase transitions. As a representative member, (C10H21NH3)2CoCl4 has been investigated in detail for crystal structure and barocaloric performance. These findings elucidate the influence of the carbon chain length on the barocaloric effect and provide a strategy for further research on barocaloric properties of organic–inorganic hybrid perovskites.