(C₂H₅NH₃)₂BiCl_5−xBr_x perovskites containing 1D chains: effect of Br substitution on their structural and optical properties

Abstract

The observed high dielectric constant of pristine chlorine in (C2H5NH3)2BiCl5−xBrx is attributed to the high polarization of the [BiCl5]2− unit as a result of its high tilting angle.

Structural Phase Transition in 0D (3,5-DMP)2Bi1–xSbxCl5 Metal Halides: Expression of the Lone Pair Effect and Polyhedral Distortion

“…bonds, while the bands at 273 (very strong) and 227 (medium) cm –1 correspond to the bridging Sb–Cl bonds . The splitting of Raman bands clearly correlates with the large difference in the bond lengths of the two bridged Sb–Cl bonds (2.94 and 3.17 Å) in the pristine Sb compound (Figure b).…”

“…The Raman band observed at 322 cm −1 corresponds to the stretching vibrational mode of the terminal Sb−Cl bonds, 66 while the bands at 273 (very strong) and 227 (medium) cm −1 correspond to the bridging Sb−Cl bonds. 32 The splitting of Raman bands clearly correlates with the large difference in the bond lengths of the two bridged Sb−Cl bonds (2.94 and 3.17 Å) in the pristine Sb compound (Figure 2b). This is in contrast to the single Raman band observed for the bridging Bi−Cl bonds in the pristine Bi analogue because of small variations in the bridging Bi−Cl bonds (2.90−2.93 Å) (Figure 2b).…”

“…This led to the search for alternate metal halides containing non-toxic inorganic metal cations like Sn 2+ , Ge 2+ , Bi 3+ , and Sb 3+ with greater stability as potential substitute of lead. Sn 2+ - and Ge 2+ -based perovskite-related materials or metal halides suffer from extremely inferior air stability and tend to decompose upon air exposure owing to the auto-oxidation of these elements from +2 to +4 state. ,,, However, Bi 3+ - and Sb 3+ -based metal halides have emerged as potential alternatives to lead-based metal halides owing to their high environmental stability, relatively low toxic nature of Bi, and enhanced optoelectronic properties. ,− Furthermore, the low-dimensional (0D, 1D, 2D) OIMHs based on Bi 3+ and Sb 3+ with bulky organic cations have been the focus of investigations in recent years because of their efficient and stable photoluminescence properties for optoelectronic applications. − Compared to 2D and 1D OIMHs, the 0D materials exhibit better stability with broadband emission, suitable for commercialization. , …”