One-pot synthesis of sandwich-structured ZnO/CsPbX3/ZnO quantum dots with continuously tunable emission for white LEDs

Perovskite quantum dots (PQDs) have shown exceptional optoelectronic properties for displays, but their practical application is hindered by low efficiency and poor stability stemming from high defect density. To address this, a one-pot synthesis has been developed, using ZnO nanocrystals (NCs) as a structure-directing agent to construct a unique sandwich architecture. These QDs consist of a ZnO core, an epitaxially grown CsPbX 3 crystalline domain, and an outer ZnO shell. Theoretical calculations reveal that ZnO incorporation significantly enhances QD stability by raising the formation energy and suppressing defect generation. Consequently, Attributed to effective defect passivation and interfacial stabilization by the ZnO sandwich structure, the PQDs exhibit a high photoluminescence quantum yield (PLQY) of 95%, compared to ~52% for the pristine counterparts. More importantly, the PQD-based composite films exhibit high stability under combined thermal, aqueous, and optical stresses, retaining over 70% of their initial PL intensity, which is markedly higher than that of <30% retained by the control samples. Moreover, continuously tunable emission from 518 to 690 nm was realized by adjusting the halide composition. A high-performance white LED was fabricated by integrating the QD composite film with a blue LED chip, achieving a color gamut covering 134% NTSC and 100% Rec. 2020. This work provides a solution through a one-pot synthesized sandwich structure that concurrently enhances both the efficiency and stability of PQDs, paving the way for future displays.