Universal Surface Repairing Strategy Enabling Suppressed Auger Recombination in CsPbBr₃ Perovskite Quantum Dots for Low Threshold Lasing in a Superlattice Microcavity

Abstract Lead halide perovskite quantum dots (LHP QDs) emerge as versatile photonic sources in electroluminescence and laser devices. Their applications in optoelectronic devices are hindered by surface distortion and ligand stripping during the purification process. In addition, the device performance roll‐off suffers from the ultrafast non‐radiative Auger recombination (AR). To address these issues, herein, CsPbBr₃ QDs are prepared with sizes ranging from 6.5 to 9.2 nm and the universal surface repairing strategy is proved to efficiently increase the biexciton lifetime and quantum yield up to 1.4 and 3 times, respectively. The strategy provides a PbBr_x rich surface and strong binding didodecyldimethylammonium bromide (DDAB) ligands to achieve near‐unity photoluminescence efficiency, which significantly improves their stability against anti‐solvents and aging in ambient conditions. A single‐mode laser device is realized by self‐assembling the QDs into superlattice as optical microcavity, with low threshold of 9.45 µJ cm⁻², quality factor of 2187 and ultrafast lifetime of 3.22 ps. The superlattice laser is demonstrated as an optical encoder with large coding bandwidth of 0.133 THz. This work proposes new insight into the non‐radiative AR process in these single‐component CsPbBr₃ QDs, and will pave the way for optoelectronic devices working in intense conditions.