The demand for cooling technologies is expected to increase significantly worldwide due to global warming caused by climate change and population growth. Therefore, there is increasing interest in efficient, sustainable and safe cooling technologies to replace current cooling processes based on green-house gases. In this regard, pressure-driven solid-state cooling based on the barocaloric phenomena represents a fascinating alternative. Open questions related to compositional and structural factors that make a good barocaloric material are currently limiting material discovery and further developments in this young field. In my presentation, I will discuss how the family of ABX3 molecular perovskites, that have been recently identified as promising barocalorics, can help to close this gap. Their building block principle allows to explore composition-structure-property relations step-by-step, focusing on the underlying phase transition thermodynamics in pressure-driven order-disorder transitions that lead to a good barocaloric performance. Motivated by this, I present a new family of dicyanamide-based molecular perovskites incorporating a series of four tailor-made A-site cations that are chemically functionalized ammonium species with flexible cyclic moieties and altering alkyl chain lengths. Following this, I will present how a substitution approach using new A-site cations in combination with various divalent B-site metals offers a chemically diverse platform to systematically study structures and phase transition thermodynamics of order-disorder phase transitions in these new molecular perovskites that are linked to the A-site chemistry, and overall, to their barocaloric performance. I will conclude with a brief summary of what crystal chemistry factors make molecular perovskites good barocalorics and how to use these for formulating general design guidelines.

ABX3 molecular perovskites as barocalorics

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.