Acylphosphine Route to Colloidal InP Quantum Dots

InP-based quantum dots (QDs) represent the major commercial success of colloidal semiconductor nanocrystals (NCs). A combination of the robust, mostly covalent, structure and nontoxic nature of the constituent elements makes them a QD material of choice for display and LED technologies. Despite successful commercial realization, InP NCs still lack synthetic versatility and robustness, seen, for instance, as a continued quest to substitute a commonly used pyrophoric and expensive tris(trimethylsilyl)phosphine precursor. Herein, we propose solid-state, nonpyrophoric, and synthetically readily accessible acylphosphines as convenient phosphorus precursors for the synthesis of InP NCs. When combined with suitable anionic nucleophiles, such as arylthiolates, both tris(acyl)phosphines and indium complexes of bis(acyl)phosphines act as efficient sources of the P^3- anion, as corroborated by NMR spectroscopy and powder X-ray diffraction studies. This type of reactivity is utilized in colloidal synthesis of uniform InP QDs with well-defined excitonic features in their optical absorption spectra, spanning 460-600 nm. The conversion kinetics and therefore the final NC size are controlled by the nature of acyl substituents and by the use of either indium or zinc long-chain carboxylates as ligands. The proposed acylpnictide route is anticipated to foster the development of other metal phosphide and metal arsenide NCs.