Finally, the Raman activity of Cs3Sb2I9 sample is consistent with the literature. The spectrum is dominated by two intense features at 148.9 and 166. literature. On the other hand, no previously data for Br/I mixed samples are available. Data in Figure show a relevant initial reduction of the (direct) band gap from about 2.5 to 2.1 eV (at 50% of Br and I), followed by a smoother reduction of the band gap up to about 2.0 eV, showing again a bowing of the Eg. A similar alloying strategy was investigated on the Cs3Bi2Br9-xIx defective perovskites reporting as well a degree of band gap bowing which is, however, less pronounced with respect to the present Sb-based perovskites.