(355c) Effect of Alloying on the Thermodynamic Stability and Optoelectronic Properties of Cesium Lead Halide Perovskites

The organic/inorganic hybrid lead halides have dominated the burgeoning field of perovskite photovoltaic research, however there is increasing interest in the all-inorganic cesium lead halide alternative for its greater chemical stability. This is tempered by the fact that, for cesium lead halide, the perovskite structure is not thermodynamically favorable at room temperature. We describe herein spectroscopic and calorimetric measurements of the influence of halide alloying on the stability and optoelectronic performance of the perovskite phase of cesium lead halides. Both enthalpic and entropic contributions have been evoked to rationalize the effects of alloying on the stability of the hybrid perovskites; herein, the competition between these two influences can be measured. Given promising initial improvements in stability, time-resolved spectroscopies are used to understand how the fundamental optoelectronic figures-of-merit, charge-carrier mobility and excited carrier lifetime, depend on alloying.