Organic-inorganic hybrid materials have sparked the interest of the materials research community due to their excellent optoelectronic properties and their broadly tunable crystal structures and chemical compositions. This rapidly growing field is mostly known for its high efficiency photovoltaic material CH3NH3PbI3.1-4 However, through compositional and chemical modifications the use of hybrid compounds can be expanded to include scintillation materials, multiferroics, light-emitting diodes, and photodetectors.5-7
Here we report the solution syntheses, crystal and electronic structures, and optical properties of the novel hybrid organic-inorganic compounds R-M-X (R = C6H5C2H4NH3, C6(CH3)5CH2N(CH3)3; M = Zn, Cd, Hg; X = Cl, Br, I). All compounds were grown under ambient conditions in various solvent systems, resulting in colorless or light-yellow millimeter-sized crystals. The stabilities of the resultant materials under ambient conditions vary depending on their chemical compositions and crystal structures. Generally, these materials have large, tunable band gaps ranging from 2.5 – 6 eV and exhibit broad photoluminescence peaks that span the entire visible spectrum. Thus, the full width at half maximum values can measure up to 220 nm. In several examples, broadband white- and bluish-white light emission can be observed at room temperature upon excitation using a 325 nm source. Based on the considerations of crystal chemistry, compositions, band structures, and past literature reports the PL emission in these materials are attributed to self-trapped exctions. On the basis of our results these R-M-X compounds may be of interest for white-light-emitting phosphors or scintillator applications.
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