Self-Assembly of Perovskite CsPbBr3 Quantum Dots Driven by Photo-Induced Alkynyl Homocoupling Reaction.

Surface-bound ligand molecules with suitable chemical and physical properties have been widely employed not only in nanocrystal synthesis where the size, morphology, phase structure, and even optoelectronic features can be defined, they have also been utilized in modulating the assembly behaviors of nanocrystals in terms of the packing modes, dimensions, as well as functionalities. Herein, we report a facile growth of 3-dimensional CsPbBr 3 perovskite supercrystals (PSCs) self-assembled from individual CsPbBr 3 perovskite quantum dot (PQD). By varying the carbon chain length of the ligand molecule, 1-alkynyl acid, different morphologies of PSCs were obtained accompanied with over 1000-fold photoluminescence improvement compared with that of PQDs. Systematic analyses have shown for the first time that under UV irradiation, CsBr, the byproduct formed during PQDs synthesis could effectively catalyze the homocoupling reaction between two alkynyl groups, which further worked as a driving force to push forward the self-assembly of PQDs. This discovery has offered a brand new and reliable strategy for growing high quality PSCs with significantly improved performance, which shall also be applicable to other nanocrystal systems aiming at unprecedented photonic, optoelectronic, and/or magnetic functionalities.