Cesium Methylammonium Lead Iodide (CsxMA1−xPbI3) Nanocrystals with Wide Range Cation Composition Tuning and Enhanced Thermal Stability of the Perovskite Phase

• Published in: Angewandte Chemie Vol. 135; no. 31
• Main Authors: Zhang, Yangning, Aly, Omar F., De Gorostiza, Anastacia, Shuga Aldeen, Thana, Segapeli, Allison J., Korgel, Brian A.
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01.08.2023
• Subjects: Alloying; Cation Exchange; Cation exchanging; Cesium; Chemistry; Composition; Crystals; Iodides; Kinetics; Mixed-Cation Perovskites; Nanocrystals; Perovskite Nanocrystals; Perovskites; Phase transitions; Photoluminescence; Photons; Rate constants; Room temperature; Thermal Stability
• ISSN: 0044-8249; 1521-3757
• DOI: 10.1002/ange.202306005

Cesium methylammonium lead iodide (CsxMA1−xPbI3) nanocrystals were obtained with a wide range of A‐site Cs‐MA compositions by post‐synthetic, room temperature cation exchange between CsPbI3 nanocrystals and MAPbI3 nanocrystals. The alloyed CsxMA1−xPbI3 nanocrystals 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 MAPbI3 nanocrystal dispersions was necessary to obtain fast Cs‐MA cation exchange. The phase transformation and degradation kinetics of films of CsxMA1−xPbI3 nanocrystals were measured and modeled using an Avrami expression. The transformation kinetics were significantly slower than those of the parent CsPbI3 and MAPbI3 nanocrystals, 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. Perovskite phase‐pure mixed‐cation CsxMA1−xPbI3 nanocrystals were obtained by post‐synthesis cation exchange between CsPbI3 and MAPbI3 nanocrystals at room temperature. The CsxMA1−xPbI3 nanocrystals exhibit composition‐tunable photoluminescence (PL) with their thermal stability that is enhanced compared to the parent CsPbI3 and MAPbI3 nanocrystals.