Abstract

Hybrid organic-inorganic metal halide materials with zero-dimensional (0D) structures have emerged as a captivating field of research due to their distinctive electronic properties and remarkable broadband emission characteristics. In this study, we successfully synthesized a novel hybrid cadmium iodide compound, (BZA)2CdI4. H2O (BZA+: benzylammonium), in the form of single crystals employing the solvent-evaporation method. The room temperature single-crystal X-ray diffraction analysis revealed that (BZA)2CdI4.H2O possesses a typical 0D crystal structure, where (CdI4)2- anions are spatially isolated and surrounded by (BZA)+ cations and H2O molecules. The crystal packing is intricately governed by various non-covalent intermolecular interactions, including 7C-7C stacking interactions, N-H...I, N-H...O, and O-H...I hydrogen bonds, quantified through Hirshfeld surface analysis. Thermal analysis further demonstrated that the removal of water molecules in the crystal lattice yields a dehydrated phase of (BZA)2(CdI4). Upon 330 nm irradiation, the title compound displayed a broad bluish-white light emission, featuring a primary band at 430 nm and a secondary band at 500 nm. Based on photoluminescence spectra measurements and density functional theory (DFT) calculations, the dual-band emission is assigned to the emission of (BZA)+ organic cations and to excitons confined in the [CdI4]2- isolated inorganic tetrahedron, respectively. Interestingly, the presence of isolated molecular units in the 0-D structure results in strongly localized charges and bluish-white light emission with Commission International de l'Eclairage (CIE) colour coordinates (0.23, 0.28). These results confirm the promise of 0D metal-halide hybrids with dual-band emission as luminescent materials for solid-state lighting.