Coordination-mediated cold quenching for the synthesis of strongly quantum-confined FAPbI3 quantum dots

Strong quantum confinement can fundamentally reshape excitonic processes and radiative recombination in perovskite quantum dots (QDs), yet accessing this regime remains challenging in organic-inorganic hybrid FAPbI3 nanocrystals because of their low crystallization barrier and rapid growth. Here, we report a coordination-mediated cold quenching strategy for synthesizing strongly quantum-confined FAPbI3 QDs with tunable emission from 696 to 759 nm. The key step involves the injection of a precooled ethyl methacrylate (EMA, –70 °C), which rapidly lowers the reaction temperature while simultaneously retarding precursor conversion and suppressing QD regrowth. Such a strategy enables small QDs with an average size of 6.4 nm and a near-unity photoluminescence quantum yield. Representative light-emitting diodes based on these QDs deliver electroluminescence at 715 nm with a peak external quantum efficiency of 16.3%. This work provides a viable strategy for accessing ultrasmall hybrid perovskite QDs and advances the rational control of quantum confinement in soft ionic semiconductors. Strong quantum confinement could improve hybrid perovskite nanocrystals, but producing ultrasmall, uniform particles is difficult. You, Wang et al. used coordination-assisted cold quenching to create efficient emitters for light-emitting diodes and optical communication.