title: Coherent Nanotwins and Dynamic Disorder in Cesium Lead Halide Perovskite Nanocrystals.
abstract: Crystal defects in highy luminescent colloidal nanocrystals (NCs) of CsPbX3perovskites (X = Cl, Br, I) are investigated. Here, using X-ray total scattering techniques and the Debye scattering equation (DSE), we provide evidence that the local structure of these NCs always exhibits orthorhombic tilting of PbX6octahedra within locally ordered subdomains. These subdomains are hinged through a two-/three-dimensional (2D/3D) network of twin boundaries through which the coherent arrangement of the Pb ions throughout the whole NC is preserved. The density of these twin boundaries determines the size of the subdomains and results in an apparent higher-symmetry structure on average in the high-temperature modification. Dynamic cooperative rotations of PbX6octahedra are likely at work at the twin boundaries, causing the rearrangement of the 2D or 3D network, particularly effective in the pseudocubic phases. An orthorhombic, 3D γ-phase, isostructural to that of CsPbBr3is found here in as-synthesized CsPbI3NCs.
authors.affiliation: Dipartimento di Scienza e Alta Tecnologia and To.Sca.Lab, Università dell'Insubria , via Valleggio 11, I-22100 Como, Italy.
authors.forename: Federica
authors.identifier: 0000-0002-6001-9040
authors.initials: F
authors.lastname: Bertolotti
authors.affiliation: Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich , Vladimir Prelog Weg 1, CH-8093 Zürich, Switzerland.|Laboratory for Thin Films and Photovoltaics, Empa - Swiss Federal Laboratories for Materials Science and Technology , CH-8600 Dübendorf, Switzerland.
authors.forename: Loredana
authors.initials: L
authors.lastname: Protesescu
authors.affiliation: Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich , Vladimir Prelog Weg 1, CH-8093 Zürich, Switzerland.|Laboratory for Thin Films and Photovoltaics, Empa - Swiss Federal Laboratories for Materials Science and Technology , CH-8600 Dübendorf, Switzerland.
authors.forename: Maksym V
authors.identifier: 0000-0002-6396-8938
authors.initials: MV
authors.lastname: Kovalenko
authors.affiliation: Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich , Vladimir Prelog Weg 1, CH-8093 Zürich, Switzerland.|Laboratory for Thin Films and Photovoltaics, Empa - Swiss Federal Laboratories for Materials Science and Technology , CH-8600 Dübendorf, Switzerland.
authors.forename: Sergii
authors.identifier: 0000-0002-6409-0565
authors.initials: S
authors.lastname: Yakunin
authors.affiliation: SLS, Laboratory for Synchrotron Radiation - Condensed Matter, Paul Scherrer Institut , CH-5232 Villigen, Switzerland.
authors.forename: Antonio
authors.initials: A
authors.lastname: Cervellino
authors.affiliation: Department of Applied Physics and Applied Mathematics, Columbia University , New York, New York 10027, United States.|Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory , Upton, New York 11973, United States.
authors.forename: Simon J L
authors.initials: SJL
authors.lastname: Billinge
authors.affiliation: Department of Applied Physics and Applied Mathematics, Columbia University , New York, New York 10027, United States.
authors.forename: Maxwell W
authors.identifier: 0000-0002-7094-1266
authors.initials: MW
authors.lastname: Terban
authors.affiliation: Department of Chemistry and Interdisciplinary Nanoscience Center (iNANO), Aarhus University , Gustav Wieds Vej 14, 8000 Aarhus, Denmark.
authors.forename: Jan Skov
authors.initials: JS
authors.lastname: Pedersen
authors.affiliation: Dipartimento di Scienza e Alta Tecnologia and To.Sca.Lab, Università dell'Insubria , via Valleggio 11, I-22100 Como, Italy.
authors.forename: Norberto
authors.identifier: 0000-0001-9921-2350
authors.initials: N
authors.lastname: Masciocchi
authors.affiliation: Istituto di Cristallografia and To.Sca.Lab, Consiglio Nazionale delle Ricerche , via Valleggio 11, I-22100 Como, Italy.
authors.forename: Antonietta
authors.identifier: 0000-0001-6390-2114
authors.initials: A
authors.lastname: Guagliardi
keywords: Debye scattering equation; colloidal nanocrystals; lead halide perovskites; nanotwins; pair distribution function