Tuning white light emission and band gap in the one-dimensional metal halide (C₆H₁₃N₄)₃Pb₂Br7 by pressure engineering

One-dimensional (1D) metal halides have become promising white-light-emitting materials because of their unique broadband emission. Understanding the relationship between the optical characteristics and crystal structures of 1D metal halides is crucial to advancing their applications in the optoelectronic field. Here, we reported the pressure-driven optical and structural responses of the 1D metal halide (HMTA)(3)Pb2Br7 (HMTA = hexamethylenetetramine, C6H13N4+, cations). The broadband emission enhancement was achieved by applying mild pressure (<0.6 GPa), accompanied by a prolongation of the carrier lifetime. Moreover, the band gap narrowed with pressure, which was attributed to the enhanced orbital coupling between the metal and halogen by lattice contraction. Our high-pressure studies not only reveal the regulation mechanism of the self-trapped exciton (STE) emission in 1D metal halides but also indicate that pressure treatment can serve as a powerful strategy to tune the emission of white-light materials.