High-quality perovskite quantum dots with excellent reproducibility and amplified spontaneous emission by optimization of cesium precursor

Lead halide perovskite quantum dots (QDs) suffer from frequent batch-to-batch inconsistencies and poor reproducibility, resulting in serious non-radiative defect-assisted recombination and Auger recombination. To overcome these challenges, in this study, CsPbBr3 QDs were prepared by designing a novel cesium precursor recipe that involved a combination of dual-functional acetate (AcO−) and 2-hexyldecanoic acid (2-HA) as short-branched-chain ligand: first, AcO− aided in significantly improving the complete conversion degree of cesium salt, enhancing the purity of the cesium precursor from 70.26% to 98.59% with a low relative standard deviation of size distribution and photoluminescence quantum yield (9.02 and 0.82%, respectively) by decreasing the formation of by-products during the reaction, which leads to enhanced homogeneity and reproducibility, especially at room temperature. Second, AcO− can act as a surface ligand to passivate the dangling surface bonds. Furthermore, compared to oleic acid, 2-HA exhibited a stronger binding affinity toward the QDs, further passivated the surface defects, and effectively suppressed biexciton Auger recombination, thereby improving the spontaneous emission rate of the QDs. Consequently, the QDs prepared using this new recipe exhibited a uniform size distribution, a green emission peak at 512 nm, a high photoluminescence quantum yield of 99% with excellent stability, and a narrow emission linewidth of 22 nm. In particular, the optimized QDs exhibited enhanced amplified spontaneous emission (ASE) performance, while the ASE threshold of treated QDs reduced by 70% from 1.8 μJ·cm−2 to 0.54 μJ·cm−2.