Investigation of earth-alkaline (EA = Mg, Ca, Sr) containing methylammonium tin iodide perovskite systems
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Methylammonium tin iodide systems containing earth-alkaline ions (CH3NH3Sn1−x (EA) x I3, EA = Ca2+, Sr2+, Mg2+, 0 ≤ x ≤ 0.30) were investigated. The X-ray diffraction patterns detected the formation of tetragonal nearly cubic CH3NH3SnI3 (space group P4mm), SnI2, and not identified phases. The morphological analysis confirmed the presence of secondary phases with formation of irregularly shaped crystallites. The Sn3d and I3d photoemission spectra revealed the typical position and separation of spin–orbit components for Sn2+ in halides. Static thermogravimetric measurements (T = 85 °C) showed a barely measurable weight loss for EA = Mg, a dramatic decrease of the weight loss rate for EA = Ca, and recorded weight losses till t ≈ 1.5 h only for EA = Sr, respectively. The optical spectra displayed absorption edges which increased at increasing the (EA)-content with maximum values for x = 0.050 (λ on-set = 1754 nm, EA = Mg; λ on-set = 1692 nm, EA = Ca; and λ on-set = 1338 nm, EA = Sr, respectively). The Tauc plots revealed a direct semiconducting behavior with band energy gaps depending on the nature and amount of the (EA)-ions. The photoluminescence (PL) spectra showed, for EA = Mg, an increase of the PL-band intensity at increasing the Mg content with a maximum at x = 1.0 and, for EA = Ca, an increase of band intensity at increasing the Ca-content and for EA = Sr, a band intensity maximum at x = 0.025. This was explained by the similar ionic radius between Sn2+ and Sr2+ ions which can be easily exchanged in the SnI6 2− octahedra.
Many thanks are owed to Mr. J.C. Jaud for technical assistance in XRD analysis and to Mrs. C. Fasel for the technical assistance in the dynamic and static thermal analysis. The authors thank the Federal Ministry of Research and Development (BMBF) (Project “Perosol” No. 03SF0483B) for the financial support during this work.
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The authors declare that they have no conflict of interest.
- 7.Environmental Health Criteria 3: Lead (World Health Organization, 1977)Google Scholar
- 8.Exposure to lead: a major public health concern (World Health Organization, 2010)Google Scholar
- 9.Howe PD, Watts P (2005) Tin and inorganic tin compounds (World Health Organization)Google Scholar
- 15.Navas J, Sánchez-Coronilla A, Gallardo JJ, Cruz Hernández N, Piñero JC, Alcántara R, Fernández-Lorenzo C, De los Santos DM, Aguilara T, Martín-Calleja J (2015) New insights into organic–inorganic hybrid perovskite CH3NH3PbI3 nanoparticles. An experimental and theoretical study of doping in Pb2+ sites with Sn2+, Sr2+, Cd2+ and Ca2+. Nanoscale 7:6216–6229CrossRefGoogle Scholar
- 18.Foster LS, Nahas HG, Lineken EE (1946) Hydroiodic acid: regeneration of oxidized solutions. In: Fernelius WC (ed) Inorganic syntheses, chap VII, vol 2. Wiley, Hoboken, p 210Google Scholar
- 23.Naumkin AV, Kraut-Vass A, Gaarenstroom SW, Powell CJ (2012) NIST Standard Reference Database 20, Version 4.1, GaithersburgGoogle Scholar
- 24.Physical constants of inorganic compounds. In: Haynes WM (ed) CRC handbook of chemistry and physics, 95th edn (Internet Version 2015). CRC Press, Boca RatonGoogle Scholar