Hybrid-Dimensional Heterostructure Enables Efficient Near-Infrared Perovskite Quantum Dot Light-Emitting Diodes.

Perovskite quantum dots (QDs) have shown promise in light-emitting diodes (LEDs) in the visible color range. Nevertheless, the efficiency and luminance of perovskite QDs in the near-infrared region (NIR, >750 nm) remain an issue. One reason comes from the liable surface and dynamic ligand binding of the ionic nature of perovskite QDs. In this work, we report a new composition to address the surface-stability issue. We achieved this by stacking QDs with quasi-2D perovskite to form a hybrid-dimensional 0D/quasi-2D structure, where the quasi-2D perovskite acts as the protecting and passivation layer to ensure a robust QD surface. Femtosecond transient absorption spectroscopy reveals that hybrid films exhibit a 3-fold longer lifetime than pure QD films. Benefiting from the protection and passivation, the hybrid films have improved stability: the emission of the hybrid film remained at 90% of its initial intensity at 400 K for 210 min, while the emission intensity of pure QD dropped to below 30% at the same conditions. Levering these benefits, we fabricated NIR QD-LEDs and achieved an external quantum efficiency of 22%, which is the record high among near-infrared perovskite QD-LEDs. Furthermore, these LEDs exhibit 6.5-fold higher stability than the best previously reported NIR perovskite QD LEDs.