Sterically Encumbered Tris(trialkylsilyl) Phosphine Precursors for Quantum Dot Synthesis

Abstract

The synthesis of nanomaterials with a narrow size distribution is challenging, especially for III−V semiconductor nanoparticles (also known as quantum dots). Concerning phosphides, this issue has been largely attributed the use of overly reactive precursors. The problem is exacerbated due to the narrow range of competent reagents for III−V semiconductor syntheses. We report the use of sterically encumbered tris(triethylsilyl) phosphine and tris(tributylsilyl) phosphine for InP quantum dot (QD) synthesis among others. The hypothesis was that these reagents are less reactive than the near-ubiquitous precursor tris(trimethylsilyl) phosphine and can be used to create more homogeneous materials. It was found that the InP products' quantum yields and emission color saturation (fwhm) were improved, but not to the levels realized in CdSe QDs. Regardless, these reagents have other positive attributes; they are less pyrophoric and can be applied toward the synthesis of II−V semiconductors and organophosphorus compounds. Concerning safe practices, we demonstrate that ammonium bifluoride is an effective replacement for highly toxic HF for the post-treatment of III−V semiconductor quantum dots.

Highly luminescent red-emitting In(Zn)P quantum dots using zinc oxo cluster: synthesis and application to light-emitting diodes

“…, tris(trimethylsilyl)phosphine (TMS 3 P) as a common P precursor) 19 hinders this separation, favors Ostwald ripening, and, hence, broadens the size distribution of InP QDs. Although Ostwald ripening can be avoided through the use of less reactive P precursors such as tris(trimethylgermyl)phosphine, tri(pyrazolyl)phosphane, aminophosphine, and white phosphorus, 20–25 the optical properties of the resulting InP QDs do not satisfy industrial criteria.…”

DFT Calculations of InP Quantum Dots: Model Chemistries, Surface Passivation, and Open-Shell Singlet Ground States

“…As a result, processed InP core QDs were etched with a small quantity of ammonium bifluoride (∼8 mg) in a solution of 0.137 g of myristic acid in 10 mL of ODE at 60 °C overnight. 28 This decreased the size to ∼1.7 nm diameter. Next, the sample was processed via precipitation with dry ethanol.…”

“…It was found that processing core QDs and treating their surfaces with various metal salts resulted in minimal impact on their optical properties (see Figure S8A). As a result, processed InP core QDs were etched with a small quantity of ammonium bifluoride (∼8 mg) in a solution of 0.137 g of myristic acid in 10 mL of ODE at 60 °C overnight . This decreased the size to ∼1.7 nm diameter.…”

ZnF2-Assisted Synthesis of Highly Luminescent InP/ZnSe/ZnS Quantum Dots for Efficient and Stable Electroluminescence

“…36,37 Various moderate alternative etchants have been examined such as 1-hexyl-3methyl-imidazolium tetrafluoroborate, 38 carboxylic acid, 39,40 and ammonium bifluoride. 41 However, these InP plain core QDs are generally unstable and require additional epitaxial growth of inorganic shells to avoid fast fluorescence degradation under ambient conditions. Recently, Won et al developed a method of introducing hydrofluoric acid as the etchant to eliminate the oxidized surface of InP cores, on which ZnSe and ZnS shells were grown consecutively at high temperature.…”