Sr-doping of perovskite quantum dots (QDs) is a promising strategy to reduce Pb content and improve optical performance and stability. However, excessive Sr introduces new defects that degrade photoluminescence quantum yield (PLQY). Therefore, it is a challenge to balance high optical performance with high doping concentration for the preparation of environmentally friendly perovskite QDs. In this study, we report the highest Sr/Pb ratios Sr-doped CsPbI₃ QDs (15.13%) with a near-unity PLQY. The balance between high PLQY and high Sr-doping rate is achieved through the introduction of oleylammonium iodide (OAmI) ligand compensation during the anti-solvent purification process, which can form an iodine-enriched environment and effectively passivates the surface defects of QDs caused by excessive Sr-doping. Moreover, the Sr-doped CsPbI₃ QDs exhibit superior stability in environments with high temperature and humidity or direct contact with water. This strategy provides a novel approach for the preparation of lead-less and lead-free QDs with superior optical performance and stability, offering a potential solution for environmentally friendly applications.

Quaternary Ag-In-Ga-S (AIGS) quantum dot (QD) is considered a promising, spectral-tunable, and environmentally friendly luminescent display material. However, the more complex surface defect states of AIGS QDs resulting from the coexistence of multiple elements lead to a low (< 60%) photoluminescence quantum yield (PLQY). Here, we develop a novel convenient method to introduce Z-type ligands ZnX₂ (X = Cl, Br, I) for passivating the surface defects of AIGS QDs to dramatically enhance the PLQY and stability without affecting the crystalline structure and morphology. Results show that the addition of ZnCl₂ during the purified process of AIGS QDs leads to a 3-fold increase of PLQY (from 28.5% to 87%). Impressively, the highest PLQY is up to a recorded value of 92%, which is comparable to typical heavy metal QDs. Exciton dynamics studies have shown that the rapid annihilation process of excitons in treated QDs is inhibited. We also confirm that the improvement in PLQY is a result of the effective passivation of the non-coordinating atom on the QD surface by building a new bonding between sulfur dangling and Zn²⁺. The realization of high PLQY will further promote the application of AIGS QDs in luminescent displays.