Thermodynamics of cesium lead halide (CsPbX3 , x= I, Br, Cl) perovskites

Inorganic cesium lead halide (CsPbX3 , x= I, Br, Cl) perovskites have sparked broad interest for photovoltaic applications, which, however, may be plagued by chemical and thermodynamic instabilities. This work reports calorimetric studies on the formation enthalpies of CsPbX3 perovskites, confirming decreasing thermodynamic stability in the order CsPbCl3 , CsPbBr3 and CsPbI3. Cesium lead iodide (CsPbI3), one of the most studied inorganic lead halide perovskites, is shown to be only barely stable from a thermodynamic perspective. This order of increasing instability is consistent with the variation of Goldschmidt tolerance factor. The perovskites are high temperature entropy-stabilized phases with respect to low temperature polymorphs, with the thermodynamics of phase transitions reflecting the above thermodynamic trends.

Automated summary

Inorganic cesium lead halide perovskites, particularly CsPbX3, have attracted significant interest for photovoltaic applications, despite facing potential issues with chemical and thermodynamic instabilities. Calorimetric studies revealed decreasing thermodynamic stability in the order CsPbCl3, CsPbBr3, and CsPbI3, with CsPbI3 being only marginally stable from a thermodynamic perspective. The variation in stability follows the Goldschmidt tolerance factor, and perovskites are shown to be entropy-stabilized high temperature phases relative to low temperature polymorphs, with phase transitions reflecting the thermodynamic trends.