Defect passivation by short-chain ligands in all-solution-processed inverted ZnSeTe green QLEDs

Abstract

High-efficiency green emission is essential for next-generation quantum dot light-emitting diodes (QLEDs); however, fully solution-processed inverted green QLEDs, particularly cadmium-free devices, are limited by surface defects, non-radiative recombination, and inefficient charge transport. Herein, we report all-solution-processed inverted ZnSeTe green QLEDs enabled by the passivation of ZnSeTe quantum dots (QDs) with the short-chain ligand of NH4PF6. This treatment effectively suppresses surface traps, prolongs photoluminescence lifetimes, and enhances carrier transport, increasing QD film conductivity from 1.42 × 10−6 to 6.15 × 10−5 S m−1 and reducing device recombination resistance from 36.2 to 16.6 kΩ. As a result, the NH4PF6-passivated QLEDs achieve a maximum external quantum efficiency of 7.3%, a peak luminance of 6732.7 cd m−2, and an operational T50 lifetime of 115 h at 100 cd m−2, a 46-fold enhancement compared to devices based on untreated QDs. These findings reveal that NH4PF6 short-chain ligands simultaneously passivate surface defects and accelerate radiative recombination, offering a viable strategy for high-efficiency, environmentally friendly green-emitting inverted QLEDs.