Boosting the Efficiency of Pure-Blue Quantum Dot Light-Emitting Diodes via a Dual-Target Treatment Strategy

Blue quantum dot light-emitting diodes (QLEDs), particularly those emitting pure-blue light in the wavelength range of 450–465 nm, still lag behind their red and green counterparts in terms of efficiency and luminance. In this work, a facile and effective LiCl dual-target treatment strategy, simultaneously engineering both the quantum dot (QD) emissive layer and the hole injection layer (HIL), is proposed for fabricating highly efficient and high-brightness pure-blue QLEDs. The strategy not only optimizes QD surface chemistry and energy level alignment with charge transport layers while mitigating fluorescence quenching at the QD/electron transport layer interface, but also improves the conductivity, light transmittance, and hole injection efficiency of the HIL. The fabricated pure-blue QLED device with the LiCl dual-target treatment (peak wavelength: 461 nm; emission line width: 19 nm) exhibits a maximum luminance of 27,210 cd/m2 and a peak external quantum efficiency of 23.44%, appreciably outperforming the untreated devices and those subjected to single LiCl treatments. To the best of our knowledge, the device surpasses the current state-of-the-art cadmium-based pure-blue QLEDs in terms of efficiency. The feasible fabrication strategy for high-performance pure-blue QLEDs and the mechanistic insights presented herein may advance QD display technologies.