title: Nearly Monodisperse Insulator Cs4PbX6(X = Cl, Br, I) Nanocrystals, Their Mixed Halide Compositions, and Their Transformation into CsPbX3Nanocrystals.
abstract: We have developed a colloidal synthesis of nearly monodisperse nanocrystals of pure Cs4PbX6(X = Cl, Br, I) and their mixed halide compositions with sizes ranging from 9 to 37 nm. The optical absorption spectra of these nanocrystals display a sharp, high energy peak due to transitions between states localized in individual PbX64-octahedra. These spectral features are insensitive to the size of the particles and in agreement with the features of the corresponding bulk materials. Samples with mixed halide composition exhibit absorption bands that are intermediate in spectral position between those of the pure halide compounds. Furthermore, the absorption bands of intermediate compositions broaden due to the different possible combinations of halide coordination around the Pb2+ions. Both observations are supportive of the fact that the [PbX6]4-octahedra are electronically decoupled in these systems. Because of the large band gap of Cs4PbX6(>3.2 eV), no excitonic emission in the visible range was observed. The Cs4PbBr6nanocrystals can be converted into green fluorescent CsPbBr3nanocrystals by their reaction with an excess of PbBr2with preservation of size and size distributions. The insertion of PbX2into Cs4PbX6provides a means of accessing CsPbX3nanocrystals in a wide variety of sizes, shapes, and compositions, an important aspect for the development of precisely tuned perovskite nanocrystal inks.
authors.affiliation: Nanochemistry Department, 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: Nanochemistry Department, 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: Computational Laboratory of Hybrid/Organic Photovoltaics (CLHYO), CNR-ISTM , via Elce di Sotto 8, I-06123 Perugia, Italy.|Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia , via Elce di Sotto 8, I-06123 Perugia, Italy.
authors.forename: Eros
authors.initials: E
authors.lastname: Radicchi
authors.affiliation: Computational Laboratory of Hybrid/Organic Photovoltaics (CLHYO), CNR-ISTM , via Elce di Sotto 8, I-06123 Perugia, Italy.|Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia , via Elce di Sotto 8, I-06123 Perugia, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Nunzi
authors.affiliation: Computational Laboratory of Hybrid/Organic Photovoltaics (CLHYO), CNR-ISTM , via Elce di Sotto 8, I-06123 Perugia, Italy.|CompuNet, Istituto Italiano di Tecnologia , Via Morego 30, 16163 Genova, Italy.
authors.forename: Edoardo
authors.initials: E
authors.lastname: Mosconi
authors.affiliation: Computational Laboratory of Hybrid/Organic Photovoltaics (CLHYO), CNR-ISTM , via Elce di Sotto 8, I-06123 Perugia, Italy.|CompuNet, Istituto Italiano di Tecnologia , Via Morego 30, 16163 Genova, Italy.
authors.forename: Filippo
authors.identifier: 0000-0003-3833-1975
authors.initials: F
authors.lastname: De Angelis
authors.affiliation: Nanochemistry Department, Istituto Italiano di Tecnologia , Via Morego 30, 16163 Genova, Italy.
authors.forename: Rosaria
authors.initials: R
authors.lastname: Brescia
authors.affiliation: Nanochemistry Department, 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: Prachi
authors.initials: P
authors.lastname: Rastogi
authors.affiliation: Nanochemistry Department, Istituto Italiano di Tecnologia , Via Morego 30, 16163 Genova, Italy.
authors.forename: Mirko
authors.identifier: 0000-0002-2188-8059
authors.initials: M
authors.lastname: Prato
authors.affiliation: Nanochemistry Department, 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: Cs4PbX6; halide perovskites; nanocrystals; synthesis; transformations