LAUSR

Abstract The control of the composition of mixed organic-inorganic hybrid perovskites by solid-state alloying is a very efficient tool to tune the band gap of the material, leading to enhanced optical performances. At this end, we have elaborated a series of mixed-halide two-dimensional hybrid perovskites (C6H11NH3)2[PbBr4−xIx], with 0 ≤ x ≤ 4, for which we studied the composition-dependence of the structural parameters and their effect on the white-light luminescence properties at room temperature. The structural analysis revealed the existence of a composition-induced structural phase transition occurring in the range 2   2), the photoluminescence spectra showed a sharp peak with a relatively small Stokes shift (less than 0.2 eV) attributed to free or bound excitons emissions. In contrast, when the bromide is majority (x