Green Synthesis of Luminous Indium Phosphide Nanocrystals

Indium phosphide (InP) nanocrystals (NCs) have garnered significant attention for displays and bioimaging due to their superior optical properties and low toxicity. However, the high cost and operational risks associated with the colloidal synthesis of InP NCs hinder their widespread development and application. In this study, we presented a green synthesis method for InP NCs using solid ammonium hypophosphite ((NH₄)H₂PO₂) as an economical and safe phosphorus precursor. (NH₄)H₂PO₂ was decomposed controllably to produce highly reactive gaseous phosphine (PH₃) through precise temperature management. The released PH₃ then reacted with indium carboxylate to form InP clusters, which serve as intermediate precursors. This cluster-assisted method endowed a continuous supply of monomers for the nucleation and growth of high-quality InP NCs with uniform size distribution. Following a surface treatment that balances etching and passivating capabilities, the InP NCs exhibited a narrow emission line width of 46 nm and a near-unity photoluminescence quantum yield (PLQY), representing one of the best emission performances for shell-less InP NCs. The economical and stable nature of the raw materials used in this approach opens a pathway for the green synthesis of InP NCs.