Carboxylic‐Free Synthesis of InP Quantum Dots for Highly Efficient and Bright Electroluminescent Device

Abstract In the synthesis of InP‐based quantum dots (QDs), the environmentally friendly carboxylic‐free phosphor precursor tris(dimethylamino)phosphine ((DMA)₃P) has been frequently used to replace tris (trimethylsilyl)phosphine (TMS)₃P, in order to prevent the InP cores from oxidation and avoid the dangerous etching with hydrofluoric acid. However, the InP‐based QDs synthesized with (DMA)₃P still perform poorly in quantum dot light‐emitting diodes (QLEDs) due to oxidation by other carboxylic sources. In this work, based on the synthesis with (DMA)₃P, ZnCl₂ precursor instead of zinc carboxylate is used for shell growing, and oleylamine is used as solvent instead of oleic acid, so that there is no oxidizing agent such as carboxylic groups during the whole synthesis process. As a result, highly efficient InP/ZnSe/ZnSeS/ZnS QDs with gradient varying shells are obtained, whose full width at half‐maximum (≈41 nm) and photoluminescence quantum yield (≈96%) are narrowest and highest among the reported ones, respectively. The QLEDs based on InP QDs synthesized with (DMA)₃P achieve breakthrough efficiency of 12.39%. Especially, high efficiency and high brightness are achieved at the same time. This work opens a new avenue in the synthesis of high‐quality and environmental friendly InP‐based QDs.