Wide band-gap tuning in Sn-based hybrid perovskites through cation replacement: the FA1-xMAxSnBr3 mixed system

We report the synthesis and characterization of the first Sn-based mixed system, namely FA(1-x)MA(x)SnBr(3) (0 <= x <= 1), providing also the first study of the FASnBr(3) hybrid perovskite. The results indicate the formation of a continuous solid solution between the two end members with a huge modulation of the band gap induced by cation replacement. These results suggest the key role of protonated amines in the electronic structure in tin-based systems and a new and effective way of tuning the band gap.