Revealing Atomic-Level Surface Passivation of PbI2-Reconditioned Red Perovskite Quantum Dots

CsPbI 3 perovskite quantum dots (QDs) are promising materials for high-efficiency and low-cost red fluorophores in advanced display and light-sensing applications. However, structural and spectral stabilities of CsPbI 3 QDs by traditional preparation are seriously broken in water or light environment. Here, a compositional engineering strategy with an additional PbI 2 -recondition process to synthesize highly-stable CsPbBr 1.2 I 1.8 @ SiO 2 QDs is demonstrated. Time- and temperature-dependent photoluminescence and Raman measurements prove that spectral stability and exciton binding energy of QDs are greatly improved within this strategy. Notably, high-resolution structure characterizations, point-to-point diffraction patterns and line-scanning of element distributions provide strong and direct evidence at atomic-level to reveal that PbI 2 -recondition can repair defects well, which helps to construct perfect lattices and homogeneous SiO 2 passivation layers to prevent the surface bonding of molecules. Moreover, our red perovskite QDs are further designed to prepare various anti-counterfeiting labels as multi-scale complex patterns to store and protect information. The proposed recondition strategy explores a new avenue to prepare stable and high-quality red perovskite QDs for new-generation lighting and light-sensing devices.