Tailoring sizes and compositions of heavy pnictogen bismuth thiohalide nanorods and nanowires via heat-up method

Abstract

Herein, we report the size and composition-controlled synthesis of pnictogen bismuth thiohalide (BiSX) nanocrystals (NCs) via the injection-free heat-up method. Colloidal BiSX nanorods (NRs) were synthesized using bismuth halides (BiX₃) precursors and elemental sulfur (S) in high boiling point solvents. The halide compositions of BiSX were systematically varied by changing the halides in the BiX₃ precursors. Phase-pure orthorhombic pnictogen BiSX NRs were synthesized in the absence of impurities. We observed that the length and width of the BiSBr NRs were tailored by changing the amounts of ODE or S precursors. In addition, the type of solvent also significantly influenced the morphology of BiSBr. Micrometer-scale BiSBr NRs were synthesized with oleic acid solvent, while thin, and high-aspect ratio BiSBr nanowires (NWs) were synthesized in 1-dodecanethiol solvent. Further, when oleylamine solvent was used, Bi₂S₃ nanotubes were obtained as the final product. We investigated the optical properties of BiSX NRs and NWs by varying the sizes and compositions. This work provides a potential guideline for synthesizing phase-pure BiSX NCs with designed optical properties by tailoring the sizes and compositions.