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

Clara Otero-Martínez; Muhammad Imran; Nadine J Schrenker; Junzhi Ye; Kangyu Ji; Akshay Rao; Samuel D Stranks; Robert L Z Hoye; Sara Bals; Liberato Manna; Jorge Pérez-Juste; Lakshminarayana Polavarapu

doi:10.1002/anie.202205617

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

Angew Chem Int Ed Engl. 2022 Aug 22;61(34):e202205617. doi: 10.1002/anie.202205617. Epub 2022 Jul 13.

Authors

Affiliations

¹ Department of Physical Chemistry, CINBIO, Universidade de Vigo, Materials Chemistry and Physics Group, Campus Universitario As Lagoas, Marcosende, 36310, Vigo, Spain.
² Department of Physical Chemistry, CINBIO, Universidade de Vigo, Campus Universitario As Lagoas, Marcosende, 36310, Vigo, Spain.
³ Nanochemistry, Istituto Italiano di Tecnologia, Via Morego 30, 16163, Genova, Italy.
⁴ EMAT and Nanolab Center of Excellence, University of Antwerp, Groenenborgerlaan 171, 2020, Antwerp, Belgium.
⁵ Cavendish Laboratory, University of Cambridge, 19 JJ Thomson Avenue, Cambridge, CB3 0HE, UK.
⁶ Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, CB3 0AS, UK.
⁷ Department of Materials, Imperial College London, Exhibition Road, London, SW7 2AZ, UK.

Abstract

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.

Keywords: Cation Exchange; Mixed A-Cation Perovskites; Perovskite Nanocrystals; Phase Segregation; Triple-Cation Perovskites.

Abstract

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