A new organic-inorganic bismuth halide crystal structure and quantum dot bearing long-chain alkylammonium cations

It is report here a new family of organic-inorganic bismuth halides bearing a formula of A2BiX5, in which A is monovalent long-chain alkylammonium and X is halide. Two compounds, (BA)2BiBr5 (BA: C4H9NH3+) and (OA)2BiBr5 (OA: C8H17NH3+), have been synthesized and investigated by single crystal and powder X-ray diffractions, UV–vis absorption and fluorescence spectroscopies, and density functional theoretical calculations. An orthorhombic crystalline structure with a P212121 space group, which had not been reported for organobismuth halides before, was found existing in (OA)2BiBr5 single crystals. Besides bulk materials, the quantum dots (QDs) of (BA)2BiBr5 and (OA)2BiBr5 were prepared and demonstrated as blue emitters with photoluminescent quantum yields of 1.26% and 0.50%, respectively, after capping with oleic acid. Finally, mixed halides with various I/Br ratios were prepared and found to form certain solid solutions with homogeneous distributed I− and Br−. Upon tuning I/Br ratio, the absorption and emission bands of their QDs can be easily modulated.