CsPbCl3 â CsPbI3 Exchange in Perovskite Nanocrystals Proceeds through a Jump-the-Gap Reaction Mechanism.
J Am Chem Soc
; 145(37): 20442-20450, 2023 Sep 20.
Article
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| MEDLINE
| ID: mdl-37691231
ABSTRACT
Halide exchange is a popular strategy to tune the properties of CsPbX3 nanocrystals after synthesis. However, while Cl â Br and Br â I exchanges proceed through the formation of stable mixed-halide nanocrystals, the Cl â I exchange is more elusive. Indeed, the large size difference between chloride and iodide ions causes a miscibility gap in the CsPbCl3-CsPbI3 system, preventing the isolation of stable CsPb(ClxI1-x)3 nanocrystals. Yet, previous works have claimed that a full CsPbCl3 â CsPbI3 exchange can be achieved. Even more interestingly, interrupting the exchange prematurely yields a mixture of CsPbCl3 and CsPbI3 nanocrystals that coexist without undergoing further transformation. Here, we investigate the reaction mechanism of CsPbCl3 â CsPbI3 exchange in nanocrystals. We show that the reaction proceeds through the early formation of iodide-doped CsPbCl3 nanocrystals covered by a monolayer shell of CsI. These nanocrystals then leap over the miscibility gap between CsPbCl3 and CsPbI3 by briefly transitioning to short-lived and nonrecoverable CsPb(ClxI1-x)3 nanocrystals, which quickly expel the excess chloride and turn into the chloride-doped CsPbI3 nanocrystals found in the final product.
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2023
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