title: Structural Stability, Vibrational Properties, and Photoluminescence in CsSnI3Perovskite upon the Addition of SnF2.
abstract: The CsSnI3perovskite and the corresponding SnF2-containing material with nominal composition CsSnI2.95F0.05were synthesized by solid-state reactions and structurally characterized by powder X-ray diffraction. Both materials undergo rapid phase transformation upon exposure to air from the black orthorhombic phase (B-γ-CsSnI3) to the yellow orthorhombic phase (Y-CsSnI3), followed by irreversible oxidation into Cs2SnI6within several hours. The phase transition occurs at a significantly lower rate in the SnF2-containing material rather than in the pure perovskite. The high hole-carrier concentration of the materials prohibits the detection of Raman signals for B-γ-CsSnI3and induces a very strong plasmonic reflectance in the far-IR. In contrast, far-IR phonon bands and a rich Raman spectrum are observed for the Y-CsSnI3modification below 140 cm-1with weak frequency shift gradients versus temperatures between -95 and +170 °C. Above 170 °C, the signal is lost due to B-α-CsSnI3re-formation. The photoluminescence spectra exhibit residual blue shifts and broadening as a sign of structural transformation initiation.
authors.affiliation: Institute of Nanoscience and Nanotechnology, NCSR Demokritos , Athens 15310, Greece.
authors.forename: Athanassios G
authors.initials: AG
authors.lastname: Kontos
authors.affiliation: Institute of Nanoscience and Nanotechnology, NCSR Demokritos , Athens 15310, Greece.
authors.forename: Andreas
authors.identifier: http://orcid.org/0000-0002-3093-9778
authors.initials: A
authors.lastname: Kaltzoglou
authors.affiliation: Institute of Nanoscience and Nanotechnology, NCSR Demokritos , Athens 15310, Greece.
authors.forename: Eirini
authors.initials: E
authors.lastname: Siranidi
authors.affiliation: Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation , Athens 11635, Greece.
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Palles
authors.affiliation: Department of Chemistry, University of Crete , Heraklion 71003, Greece.
authors.forename: Giasemi K
authors.initials: GK
authors.lastname: Angeli
authors.affiliation: Institute of Nanoscience and Nanotechnology, NCSR Demokritos , Athens 15310, Greece.
authors.forename: Michalis K
authors.initials: MK
authors.lastname: Arfanis
authors.affiliation: Institute of Nanoscience and Nanotechnology, NCSR Demokritos , Athens 15310, Greece.
authors.forename: Vassilis
authors.initials: V
authors.lastname: Psycharis
authors.affiliation: Faculty of Applied Sciences, National Technical University of Athens , Athens 15780, Greece.
authors.forename: Yannis S
authors.initials: YS
authors.lastname: Raptis
authors.affiliation: Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation , Athens 11635, Greece.
authors.forename: Efstratios I
authors.initials: EI
authors.lastname: Kamitsos
authors.affiliation: Department of Chemistry, University of Crete , Heraklion 71003, Greece.
authors.forename: Pantelis N
authors.initials: PN
authors.lastname: Trikalitis
authors.affiliation: Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States.
authors.forename: Constantinos C
authors.identifier: http://orcid.org/0000-0001-8396-9578
authors.initials: CC
authors.lastname: Stoumpos
authors.affiliation: Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States.
authors.forename: Mercouri G
authors.initials: MG
authors.lastname: Kanatzidis
authors.affiliation: Institute of Nanoscience and Nanotechnology, NCSR Demokritos , Athens 15310, Greece.
authors.forename: Polycarpos
authors.identifier: http://orcid.org/0000-0002-9553-5301
authors.initials: P
authors.lastname: Falaras