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Fast A-Site Cation Cross-Exchange at Room Temperature: Single-to Double- and Triple-Cation Halide Perovskite Nanocrystals.

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Otero-Martínez, Clara 
Schrenker, Nadine J 
Ye, Junzhi 
Ji, Kangyu 


We report here fast A-site cation cross-exchange between APbX3 perovskite nanocrystals (NCs) made of different A-cations (Cs (cesium), FA (formamidinium), and MA (methylammonium)) at room temperature. Surprisingly, the A-cation cross-exchange proceeds as fast as the halide (X=Cl, Br, or I) exchange with the help of free A-oleate complexes present in the freshly prepared colloidal perovskite NC solutions. This enabled the preparation of double (MACs, MAFA, CsFA)- and triple (MACsFA)-cation perovskite NCs with an optical band gap that is finely tunable by their A-site composition. The optical spectroscopy together with structural analysis using XRD and atomically resolved high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and integrated differential phase contrast (iDPC) STEM indicates the homogeneous distribution of different cations in the mixed perovskite NC lattice. Unlike halide ions, the A-cations do not phase-segregate under light illumination.


Funder: Royal Society; Id:


Cation Exchange, Mixed A-Cation Perovskites, Perovskite Nanocrystals, Phase Segregation, Triple-Cation Perovskites

Journal Title

Angew Chem Int Ed Engl

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European Research Council (756962)
Engineering and Physical Sciences Research Council (EP/R023980/1)