Dual‐Surface Treatment for Efficient Amine‐Phosphine Based Red InP QLEDs

Abstract Indium phosphide (InP)‐based quantum dots (QDs) have emerged as highly‐promising, environmentally friendly emitting materials for displays. However, the commonly used phosphorus precursor, tris(trimethylsilyl)phosphine ((TMS) ₃ P), is expensive, flammable, and explosive, hindering its commercialization. Although tris(dimethylamino)phosphine ((DMA) ₃ P) offers a more economical alternative, the resulting QDs and quantum dot light‐emitting diodes (QLEDs) have low performance because of core surface traps and ligand instability. In this study, a dual‐surface treatment strategy is developed that combines NH ₄ PF ₆ pre‐treatment of InP cores and OT‐based shell growth. First, NH ₄ PF ₆ is employed to passivate the In/P dangling bonds and remove the oxidation defects, thereby improving size uniformity. Then, 1‐octanethiol (OT) served as both sulfur source and short‐chain ligand to enhance QD stability. The optimized QDs exhibit a near‐unity photoluminescence quantum yield (PL QY) of 96% and exceptional stability, retaining 98% of their initial PL QY after 1 month in ambient air. Moreover, the OT ligand facilitates an elevated energy‐level alignment, reducing the hole injection barrier and boosting radiative recombination. As a result, the OT‐based red QLEDs achieve a record external quantum efficiency (EQE) of 21.55%, maximum luminance of 95,327 cd m ⁻² , and long T ₅₀ lifetime (time for the luminance to drop to half of the initial value) of 50,066 h, setting a new state‐of‐the‐art performance for (DMA) ₃ P‐based QLEDs.