Role of Acid in Precursor Conversion During InP Quantum Dot Synthesis

Abstract

We have studied the speciation of P(SiMe3)3 during the synthesis of colloidal InP quantum dots in the presence of proton sources. Using 31P NMR spectroscopy, we show H3-nP(SiMe3)n formation on exposure of P(SiMe3)3 to a variety of protic reagents including water, methanol, and carboxylic acid, corroborating observations of P(SiMe3)3 speciation during the hot injection synthesis of InP QDs. Quantitative UV–vis comparisons between InP growth from P(SiMe3)3 and HP(SiMe3)2 show unambiguously that when total H+-content is accounted for, particle size, size dispersity, and concentration are indistinguishable for these two reagents. The dual role of myristic acid in P–Si bond cleavage and as a source of the myristate anion, an essential component of the quantum dot surface, is interrogated using tetrabutylammonium myristate, confirming that it is the protons that are responsible for increased quantum dot polydispersity. Together these data support the existence of a competing acid-catalyzed pathway in the conver...