Multifunctional ligand modification enabling high-performance air-processed NIR perovskite QLEDs

The adopted NMAI serves multifunctions: it barricades water/oxygen against ambient degradation, passivates defects to suppress non-radiative recombination, and tunes interfacial energy alignment to balance carrier dynamics. • High luminescence and air stability are simultaneously achieved in perovskite quantum dots via one additive, with PLQY reaching 87.9% and ambient stability over twice the reference. • Ambient-air fabricated NIR-PQLEDs exhibit a peak EQE of 16.15% and T 50 over 140 min, showing over 3-fold EQE and 4-fold operational lifetime relative to control devices. Near-infrared perovskite quantum-dot light-emitting diodes (NIR-PQLEDs) are promising for broad application prospects such as biological imaging and optical communication. However, due to the influence of water and oxygen, the stability of perovskite quantum dots (PQDs) in air environments is usually poor, which hinders their industrial applications. In this work, by introducing multifunctional ligand 1-naphthylmethylammonium iodide (NMAI) for surface modification of PQDs, we successfully realized high-efficiency and stable NIR-PQLEDs fabricated under ambient air conditions. Here, NMAI mainly possesses the following functions: 1) Its hydrophobic aromatic naphthalene group enhances the surface hydrophobicity of PQDs and contributes to a more compact moisture-resistant ligand shell, thereby effectively suppressing water and oxygen erosion under ambient air conditions. 2) The synergistic effect of NMA + cations and I − anions achieves efficient defect passivation, thus suppressing non-radiative recombination. 3) The inherent dipole characteristic of NMAI reconstructs the surface of PQDs, optimizing interfacial energy-level alignment and balancing carrier dynamics. Consequently, the photoluminescence quantum yield (PLQY) of PQD film increases from 74.4% to 87.9%, with remarkably enhanced stability in air environment. Benefiting from this strategy, air-processed NIR-PQLEDs achieve a peak external quantum efficiency (EQE) of 16.15%, representing a more than threefold enhancement compared to the pristine device. Meanwhile, the operational half-lifetime (T 50 ) is extended by more than fourfold to over 140 min. This work provides a novel strategy for air-compatible, low-cost, and scalable fabrication of high-performance NIR-PQLEDs, which is of great significance for advancing their optoelectronic applications in the future.