Manipulating Thermal Transport in Two-Dimensional Organic–Inorganic Perovskites

Two-dimensional (2-D) organic–inorganic perovskites containing first-row transition metals and long-chain organic cations have recently been explored for thermal applications, including thermal energy storage and solid-state barocaloric cooling. Controlling the thermal conductivity of these materials is essential to capturing their value in practical systems, yet few studies have examined the transport mechanisms of these structures. Most importantly, much remains to be understood about the chemical and structural factors that regulate thermal transport at a molecular level. We report systematic investigations into the thermal conductivity of 2-D perovskites, seeking to understand the role of chemical interactions at the organic–organic interface in dictating thermal transport. Variable temperature frequency-domain thermoreflectance and nanomechanical indentation measurements were performed on a library of 2-D Mn–Cl perovskites to probe the relationship between structural features and the character of thermal vibrations. These measurements were carried out across their order–disorder phase transitions to evaluate the effects of structural disorder on thermal transport. Additionally, 2-D perovskites whose organic bilayers feature an array of chain flexibilities and chemical interaction networks have been explored in the context of tuning thermal conductivity <i>via </i>interlayer adhesion strengths.