Revealing Atomic-Level Surface Passivation of PbI_2-Reconditioned Red Perovskite Quantum Dots

摘要

CsPbI3 perovskite quantum dots (QDs) are promising materials for high-efficiencyand low-cost red fluorophores in advanced display and light-sensingapplications. However, structural and spectral stabilities of CsPbI_3 QDs bytraditional preparation are seriously broken in water or light environment.Here, a compositional engineering strategy with an additional PbI_2-reconditionprocess to synthesize highly-stable CsPbBr_(1.2)I_(1.8) @ SiO_2 QDs is demonstrated.Time- and temperature-dependent photoluminescence and Ramanmeasurements prove that spectral stability and exciton binding energy ofQDs are greatly improved within this strategy. Notably, high-resolution structurecharacterizations, point-to-point diffraction patterns and line-scanningof element distributions provide strong and direct evidence at atomic-level toreveal that PbI_2-recondition can repair defects well, which helps to constructperfect lattices and homogeneous SiO_2 passivation layers to prevent thesurface bonding of molecules. Moreover, our red perovskite QDs are furtherdesigned to prepare various anti-counterfeiting labels as multi-scale complexpatterns to store and protect information. The proposed recondition strategyexplores a new avenue to prepare stable and high-quality red perovskite QDsfor new-generation lighting and light-sensing devices.