Structural regulation and optical behavior of zero-dimensional Cu(I)-based organometallic halides under pressure

Low-dimensional hybrid metal halides exhibit broadband emission and high photoluminescence quantum yield (PLQY), making them promising candidates for the next-generation luminescent materials in lighting applications. Here, the emission intensity of (C₁₂H₂₄O₆)₂Na₂(H₂O)₃Cu₄I₆ was strengthened between 9.3 GPa and 17.2 GPa, accompanied by the redshift of emission wavelength. The photoluminescence (PL) of Cu(I)-based organometallic halides originates from multiple emission states, which are a metal-to-ligand charge transfer or a halide-to-ligand charge transfer (MLCT/HLCT) excited state and a cluster-centered (CC) excited state. MLCT/HLCT-related emission wavelength redshifts while CC-related emission wavelength remains unchanged, indicating that the rearrangement of different emission states plays a critical role in the changes of luminescence wavelength. This study not only deepens the understanding of the influence of high pressure on (C₁₂H₂₄O₆)₂Na₂(H₂O)₃Cu₄I₆, but also provides valuable insights into the structure–property relationship of zero-dimensional Cu(I)-based organometallic halides.