Colloidal perovskite nanocrystal (PeNC) has long been synthesized using the hot-injection method and room-temperature ligand-assisted reprecipitation as the prominent techniques1,2. However, both methods have challenges for industrial-scale production3–5: the hot-injection method requires high temperatures, an inert gas environment and rapid cooling, which raise safety concerns, whereas ligand-assisted reprecipitation can exhibit limited productivity on scale-up. Here we present a cold-injection method based on pseudo-emulsion, enabling scalable synthesis of PeNCs with near-unity photoluminescence quantum yield (PLQY, ~100%) and enhanced stability by injecting precursor solution below 4 °C. In the cold-injection method, PeNCs grow through the assembly of fully coordinated plumbates out of the pseudo-emulsion with the assistance of a demulsifier. We discovered that slow assembly of polybromide plumbates, assisted by cold temperature, is essential for defect suppression, resulting in reproducible, stable and pure-green-emitting PeNCs with near-unity PLQY. Furthermore, this method enables efficient large-scale production, achieving 20-l-scale synthesis with remarkable batch weight while maintaining near-unity PLQY. Our findings represent a substantial advancement in synthesis of high-quality PeNCs, offering potential for broad applications in display and lighting industries.
