title: In Situ Transmission Electron Microscopy Study of Electron Beam-Induced Transformations in Colloidal Cesium Lead Halide Perovskite Nanocrystals.
abstract: An increasing number of studies have recently reported the rapid degradation of hybrid and all-inorganic lead halide perovskite nanocrystals under electron beam irradiation in the transmission electron microscope, with the formation of nanometer size, high contrast particles. The nature of these nanoparticles and the involved transformations in the perovskite nanocrystals are still a matter of debate. Herein, we have studied the effects of high energy (80/200 keV) electron irradiation on colloidal cesium lead bromide (CsPbBr3) nanocrystals with different shapes and sizes, especially 3 nm thick nanosheets, a morphology that facilitated the analysis of the various ongoing processes. Our results show that the CsPbBr3nanocrystals undergo a radiolysis process, with electron stimulated desorption of a fraction of bromine atoms and the reduction of a fraction of Pb2+ions to Pb0. Subsequently Pb0atoms diffuse and aggregate, giving rise to the high contrast particles, as previously reported by various groups. The diffusion is facilitated by both high temperature and electron beam irradiation. The early stage Pb nanoparticles are epitaxially bound to the parent CsPbBr3lattice, and evolve into nonepitaxially bound Pb crystals upon further irradiation, leading to local amorphization and consequent dismantling of the CsPbBr3lattice. The comparison among CsPbBr3nanocrystals with various shapes and sizes evidences that the damage is particularly pronounced at the corners and edges of the surface, due to a lower diffusion barrier for Pb0on the surface than inside the crystal and the presence of a larger fraction of under-coordinated atoms.
authors.affiliation: Department of Nanochemistry, Istituto Italiano di Tecnologia , Via Morego 30, 16163 Genova, Italy.
authors.forename: Zhiya
authors.initials: Z
authors.lastname: Dang
authors.affiliation: Department of Nanochemistry, Istituto Italiano di Tecnologia , Via Morego 30, 16163 Genova, Italy.|Dipartimento di Chimica e Chimica Industriale, Università degli Studi di Genova , Via Dodecaneso, 31, 16146 Genova, Italy.
authors.forename: Javad
authors.initials: J
authors.lastname: Shamsi
authors.affiliation: Department of Nanochemistry, Istituto Italiano di Tecnologia , Via Morego 30, 16163 Genova, Italy.
authors.forename: Francisco
authors.initials: F
authors.lastname: Palazon
authors.affiliation: Department of Nanochemistry, Istituto Italiano di Tecnologia , Via Morego 30, 16163 Genova, Italy.|Dipartimento di Chimica e Chimica Industriale, Università degli Studi di Genova , Via Dodecaneso, 31, 16146 Genova, Italy.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Imran
authors.affiliation: Department of Nanochemistry, Istituto Italiano di Tecnologia , Via Morego 30, 16163 Genova, Italy.|Dipartimento di Chimica e Chimica Industriale, Università degli Studi di Genova , Via Dodecaneso, 31, 16146 Genova, Italy.
authors.forename: Quinten A
authors.initials: QA
authors.lastname: Akkerman
authors.affiliation: Department of Nanochemistry, Istituto Italiano di Tecnologia , Via Morego 30, 16163 Genova, Italy.|Department of Physics, Pukyong National University , Busan 608-737, Korea.
authors.forename: Sungwook
authors.initials: S
authors.lastname: Park
authors.affiliation: Department of Nanochemistry, Istituto Italiano di Tecnologia , Via Morego 30, 16163 Genova, Italy.|IMEM-CNR , Parco Area delle Scienze 37/A, Parma 43124, Italy.
authors.forename: Giovanni
authors.identifier: 0000-0001-6424-9102
authors.initials: G
authors.lastname: Bertoni
authors.affiliation: Department of Nanochemistry, Istituto Italiano di Tecnologia , Via Morego 30, 16163 Genova, Italy.
authors.forename: Mirko
authors.initials: M
authors.lastname: Prato
authors.affiliation: Department of Nanochemistry, Istituto Italiano di Tecnologia , Via Morego 30, 16163 Genova, Italy.
authors.forename: Rosaria
authors.initials: R
authors.lastname: Brescia
authors.affiliation: Department of Nanochemistry, Istituto Italiano di Tecnologia , Via Morego 30, 16163 Genova, Italy.
authors.forename: Liberato
authors.identifier: 0000-0003-4386-7985
authors.initials: L
authors.lastname: Manna
keywords: TEM; cesium lead halide nanocrystals; radiation damage