Molecular Iodine for a General Synthesis of Binary and Ternary Inorganic and Hybrid Organic-Inorganic Iodide Nanocrystals

We report the synthesis of various binary and ternary inorganic and hybrid organic-inorganic iodide nanocrystals (NCs) starting from molecular iodine (I₂). The synthesis described herein utilizes a reaction between I₂ and oleylamine, which results in oleylammonium iodide, an iodide precursor that can be directly used in the preparation of iodide-based NCs. The generality of the synthesis was demonstrated by synthesizing KI, RbI, CsI, AgI, CsPbI₃, FAPbI₃, Cs₄PbI₆, Cs₃Bi₂I₉, FA₃Bi₂I₉, and RbAg₄I₅ NCs. Furthermore, the syntheses are facile and are carried out in vials heated on a hot plate in air. They exhibit not only narrow size distributions, but also, in the case of lead-based perovskites NCs, 70-80% photoluminescence quantum yields. To further prove the high quality of the CsPbI₃ and FAPbI₃ perovskite NCs, red and infrared bright light-emitting diodes were fabricated, with external quantum efficiencies (EQEs) exceeding 3%, without following any extensive washing procedures.