The present results provide a novel sustainable synthetic route to prepare Sb-based defective perovskites and, more importantly, two alloying strategies which allow to tune the band gap in most of the visible spectrum providing also the first evidence of band gap reduction by metal mixing (Sb/Bi) in a defective perovskite structure. Such effect has been only previously observed in double perovskites (Cs2AgSbxBi(1-x)Br6) suggesting its possible universal character which is worth of being further explored in other related systems.