Tailoring Morphology and Composition of Colloidal Metal Phosphide Nanocrystals with Prenucleation Complexes

Colloidal metal phosphide nanocrystals have been extensively explored for energy conversion, optoelectronic devices, and bioimaging applications. However, colloidal synthesis to achieve precise control over size, morphology, and composition remains extremely challenging for these phosphide nanocrystals. This is partly due to the unbalanced reactivity of the metal and phosphide precursors and a poor understanding of their formation mechanisms. Herein, we have utilized defined prenucleation metal-aminophosphine-alkylamine complexes as precursors for the highly tunable synthesis of colloidal metal phosphide nanomaterials with accurate control over morphology and composition. We show that precise control over morphology and composition can be achieved using a highly customizable prenucleation-complex-based method for metal phosphide nanocrystals. Using 31P-nuclear magnetic resonance spectroscopy and mass spectrometry, we reveal the prenucleation complex formation mechanisms and provide a structural analysis of the M-P (M = Cu, Co, Cd, and Ni) complexes. Moreover, we investigated the morphology and structure of the phosphide nanocrystals using electron microscopy and X-ray diffraction experiments. We have further used first-principles calculations and boundary element method-based simulations to gain insights into the structural evolution of these nanocrystals as well as into the impact of the morphology and composition on their plasmonic response. We anticipate that the generalized prenucleation-based colloidal metal phosphide synthesis with precise control of size, shape, and composition could pave the way to yield high-quality metal phosphide nanocrystals with tailored chemical and optoelectronic properties.