Interfacial Dipole Engineering of NiO x Enables High‐Efficiency Deep‐Blue Quantum Dot Light‐Emitting Diodes

ABSTRACT Carrier imbalance arising from insufficient hole injection remains a major obstacle to achieving high‐efficiency blue quantum‐dot light‐emitting diodes (QLEDs). Here, we introduce fluorinated self‐assembled monolayers (SAMs) onto NiO x hole‐injection layers to regulate the interfacial electronic structure and hole injection. Molecular modification induces pronounced interfacial dipoles and shifts the valence‐band maximum (VBM) of NiO x toward deeper energy levels, thereby improving energy‐level alignment. Among the investigated modifiers, pentafluorobenzyl phosphonic acid (F 5 BnPA) produces the strongest interfacial modulation, yielding a VBM of −5.65 eV and a reduced hole‐injection barrier. Consequently, the optimized deep‐blue QLEDs deliver a maximum luminance of 31163 cd m −2 and a peak external quantum efficiency of 19.68%, with Commission Internationale de l'Éclairage (CIE) coordinates of (0.15, 0.03) and excellent spectral stability. These results represent one of the highest efficiencies reported for blue QLEDs employing metal‐oxide hole‐injection layers and highlight the critical role of molecular dipole engineering in tailoring oxide/organic interfaces for high‐performance deep‐blue QLEDs.