Green and Scalable Synthesis of Efficient and Stable CsPbBr 3 Perovskite Quantum Dots Enables Low‐Threshold Amplified Spontaneous Emission

ABSTRACT Halide perovskite quantum dots (PeQDs) are promising as gain materials for amplified spontaneous emission (ASE), yet their environmentally friendly and scalable wet‐chemistry synthesis remains challenging. Meanwhile, severe nonradiative‐recombination channels impair ASE performance of neat PeQDs. Herein, we demonstrate a green and scalable strategy employing bio‐sourced zwitterionic lecithin as a ligand and hexane as a solvent. This approach enables single‐batch production of high‐quality CsPbBr 3 PeQDs of over 10 grams, with potential scaling‐up using industrial equipment. Theoretical calculations and experimental characterizations reveal that such scalability stems from suppressed Ostwald ripening, driven by the synergistic covalent and electrostatic interactions between PeQD surface and the functional groups. The resulting PeQDs exhibit remarkably inhibited nonradiative recombination from both Auger recombination and electron‐phonon coupling, alongside a high photoluminescence quantum yield of 95%. Lecithin also endows PeQDs with enhanced stability under air, UV irradiation, heat, and polar solvents. Benefiting from such merits, lecithin‐PeQDs achieve outstanding ASE performance with significantly low thresholds of 230.4 and 50.1 µJ cm − 2 under nanosecond and femtosecond laser excitation, respectively, both representing state‐of‐the‐art levels for neat PeQD films. This work not only provides a green and efficient route for mass production of PeQDs, but opens a new avenue for designing high‐performance gain materials.