Tailoring Dynamic Charge Response and Trap-State Landscapes with Targeted Phosphine Oxide Additive for Efficient FAPbBr3 Quantum-Dot Light-Emitting Diodes

Abstract Formamidinium lead bromide (FAPbBr3) perovskite quantum dots (PeQDs) are promising emitters for next-generation displays owing to their narrow emission, high color purity, and solution processability. However, surface-derived trap states promote nonradiative recombination and charge accumulation, limiting PeQLED performance. Here, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is introduced during PeQD synthesis to regulate surface coordination. Spectroscopy supports coordination of its electron-rich P═O group with undercoordinated Pb2+ sites, thereby suppressing trap-assisted nonradiative recombination. Reduced Urbach energy and comparative space-charge-limited-current trap-density estimates support lower energetic disorder, while frequency-resolved electrical measurements indicate diminished slow charge relaxation and trap-mediated charge accumulation. Consequently, the optimized PeQLED achieves a peak external quantum efficiency of 18.3%, a maximum luminance of 75,180 cd m–2, and a current efficiency of 85.4 cd A–1. These results link molecular surface coordination with nonradiative-loss suppression and dynamic charge regulation, providing a strategy for efficient PeQLEDs.