Tailoring Dynamic Charge Response and Trap-State Landscapes with Targeted Phosphine Oxide Additive for Efficient
Xinning Wang1, Yujie Wen1, Di Shen1
1Key Laboratory of Advanced Technologies of Materials (Ministry of Education), School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu610031, P. R. China.
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.
