Short Aromatic Diammonium Ions Modulate Distortions in 2D Lead Bromide Perovskites for Tunable White-Light Emission

White-light broadband emission in the visible range from low-dimensional halide perovskites is commonly attributed to structural distortions lead bromide octahedra. In this paper, we report Dion–Jacobson-phase two-dimensional (2D) based on short aromatic diammonium cations, p-phenylene (pPDA), m-phenylene (mPDA), and two 1D compounds templated by o-phenylene (oPDA). All of exhibit white-light emission. Single-crystal X-ray diffraction analysis reveals that distortion Pb octahedra influenced stereochemistry cations their interactions with perovskite layers. Solid-state 1H 207Pb NMR spectroscopy further confirms trend, whereby different chemical shifts are observed for pPDA mPDA spacer indicating hydrogen-bonding octahedral distortions. Owing distortion, 2D (mPDA)PbBr4 broader than (pPDA)PbBr4. Density functional theory calculations suggest (pPDA)PbBr4 direct-band-gap semiconductors, they larger electronic band gaps effective masses Ruddlesden–Popper-phase (BA)2PbBr4. Among films these compounds, shows best stability, which stronger material.