Investigation of Methylammonium Tin Strontium Bromide Perovskite Systems

Abstract

The properties of methylammonium-tin-strontium bromide systems (CH 3 NH 3 Sn 1-x Sr x Br 3 , 0.0 ≤ x ≤ 0.1) were investigated. The X-ray diffraction analysis (XRD) revealed the presence of the untilted cubic Pm-3m perovskite and orthorhombic SnBr 2 as major crystalline phases. The morphological analysis confirmed the XRD data by detecting the formation of polyhedral shaped crystallites attributed to MASnBr 3 perovskite and elongated crystallites related to SnBr 2 phase. Derivative differential thermal analysis (DDTA) and derivative thermogravimetric analysis (DTG) revealed a thermal stability of MASnBr 3 phase till T = 250 • C and showed the presence of more thermal events related to a multistep decomposition process. The addition of Sr-ions retained the cubic crystalline structure of the perovskite and enhanced its thermal stability at T = 150 • C by reducing the weight loss rates. The optical spectra displayed values of absorption edges between 624 nm and 636 nm. The Tauc plots revealed a direct semiconducting behavior with band energy gaps at ∼2.02-2.03 eV. The emission photoluminescence (PL) spectra, measured at room temperature and excitation wavelength λ exc = 380 nm as well as the excitation photoluminescence (PL) spectra, measured at room temperature and emission wavelength λ em = 520 nm showed a dramatic increase of the intensity by adding the Sr-ions reaching a maximum for x = 0.025.

Unveiling Predominant Air-Stable Organotin Bromide Perovskite toward Mechanical Energy Harvesting

“…By increasing the annealing temperature of MASnBr 3 films from 195 to 210 °C, a slight increase of the SnBr 2 peak was observed (Figure S4a) that may increase the stability of MASnBr 3 films when compared with the 195 °C-annealed MASnBr 3 films. However, a melt-like morphology was observed for 210 °C-annealed MASnBr 3 films as shown in the SEM image (Figure S4b) when compared to 195 °C-annealed MASnBr 3 films (Figure S4c), which could be because of the melting of SnBr 2 . Thus, in this study, the temperature 195 °C was considered as the appropriate annealing temperature of MASnBr 3 films to achieve high air -stability without any morphological changes.…”

“…However, a melt-like morphology was observed for 210 °C-annealed MASnBr 3 films as shown in the SEM image (Figure S4b) when compared to 195 °C-annealed MASnBr 3 films (Figure S4c), which could be because of the melting of SnBr 2 . 55 Thus, in this study, the temperature 195 °C was considered as the appropriate annealing temperature of MASnBr 3 films to achieve high air -stability without any morphological changes. The captured photographic images of the as-deposited, 180 °Cand 195 °Cannealed MASnBr 3 films that were exposed to air show color variations with respect to time (Figure S5).…”