Search for: All records

Abstract Cesium methylammonium lead iodide (Cs_xMA_1−xPbI₃) nanocrystals were obtained with a wide range of A‐site Cs‐MA compositions by post‐synthetic, room temperature cation exchange between CsPbI₃nanocrystals and MAPbI₃nanocrystals. The alloyed Cs_xMA_1−xPbI₃nanocrystals retain their photoactive perovskite phase with incorporated Cs content,x, as high as 0.74 and the expected composition‐tunable photoluminescence (PL). Excess methylammonium oleate from the reaction mixture in the MAPbI₃nanocrystal dispersions was necessary to obtain fast Cs‐MA cation exchange. The phase transformation and degradation kinetics of films of Cs_xMA_1−xPbI₃nanocrystals were measured and modeled using an Avrami expression. The transformation kinetics were significantly slower than those of the parent CsPbI₃and MAPbI₃nanocrystals, with Avrami rate constants,k, at least an order of magnitude smaller. These results affirm that A‐site cation alloying is a promising strategy for stabilizing iodide‐based perovskites.