Εξειδίκευση τύπου :	Άρθρο σε επιστημονικό περιοδικό
Τίτλος:	Temperature effects on the vibrational properties of the Cs2SnX6 ‘defect’ perovskites (X = I, Br, Cl)
Δημιουργός/Συγγραφέας:	Belessiotis, G.V. Arfanis, M. [EL] Καλτζόγλου, Ανδρέας[EN] Kaltzoglou, Andreas Likodimos, V. Raptis, Y.S. Falaras, P. Kontos, A.G.
Ημερομηνία:	2021-04-23
Γλώσσα:	Αγγλικά
ISSN:	02540584
DOI:	10.1016/j.matchemphys.2021.124679
Περίληψη:	Air-stable, vacancy-ordered double perovskites Cs2SnX6 (X = Cl, Br, I) have been attracting particular interest due their potential applications in solar cells and thermoelectrics based on their favorable structural, optical and transport properties. In this work, a comprehensive Raman investigation of Cs2SnX6 perovskites is performed over an extended temperature range of 83–433 K in order to provide insight to their lattice dynamics. Substitution of the lighter and more electronegative Cl halogens with the heavier bromide and iodide ones resulted in the decrease of the frequencies for all Raman modes comprising the internal vibrations in the SnX6 octahedra and the νL(F2g) mode due to Cs vibrations against SnX6 in the rigid lattice. Blue shift and narrowing of the SnX6 stretching and bending bands was invariably observed for all halogen analogues with temperature decrease, evidencing the presence of lattice anharmonicity. More importantly, the elusive νL(F2g) phonon was only observed for Cs2SnCl6 for all temperatures, complying with the predictions of Hirshfeld surface analysis for the enhanced Cs–SnCl6 interactions. The latter mode emerged for Cs2SnI6 only above room temperature, indicating that combination of anharmonic lattice dynamics with the increased Cs–SnI6 oscillation energy upon increasing temperature may activate this specific “lattice mode”, which in the limit of very weak Cs–I interaction approaches the “rattling’’ Cs vibrations in the cuboctahedral cage. Strong lattice anharmonicity for the chemically stable Cs2SnX6 compounds can be accordingly inferred, which is a key aspect for their performance in future optoelectronic and thermoelectric applications.
Τίτλος πηγής δημοσίευσης:	Materials Chemistry and Physics
Τόμος/Κεφάλαιο:	267
Θεματική Κατηγορία:	[EL] Ανόργανη χημεία[EN] Inorganic chemistry
Λέξεις-Κλειδιά:	Perovskite halides Defect perovskites Raman spectroscopy Anharmonicity Lattice modes
EU Grant:	Deposition of Perovskite Halides Thin Films with Controlled Crystallinity and study of their Structural and Optoelectronic Properties
EU Grant identifier:	5049176
Ηλεκτρονική διεύθυνση στον εκδότη (link):	https://www.sciencedirect.com/science/article/pii/S0254058421004624
Σημειώσεις:	This research is carried out/funded in the context of the project “Deposition of Perovskite Halides Thin Films with Controlled Crystallinity and study of their Structural and Optoelectronic Properties” (MIS: 5049176) under the call for proposals “Researchers' support with an emphasis on young researchers- 2nd Cycle”. The project is co-financed by Greece and the European Union (European Social Fund- ESF) by the Operational Programme “Human Resources Development, Education and Lifelong Learning”, 2014–2020.
Εμφανίζεται στις συλλογές:	Ινστιτούτο Θεωρητικής και Φυσικής Χημείας (ΙΘΦΧ) - Επιστημονικό έργο