The Narrow Synthetic Window for Highly Homogenous InP Quantum Dots toward Narrow Red Emission

Abstract

Low-toxicity InP-based quantum dots (QDs) exhibit potential for replacing Cd/Pb-containing QDs in the visible and near-infrared regions. Despite advancements, further improvement relies on synthesizing homogeneous InP QDs to achieve a high color purity. In a commonly employed two-step "seed-mediated" synthetic approach, we demonstrate the high sensitivity of InP seed sizes and size distribution to the quantities of trioctylphosphine (TOP) and tris(trimethylsilyl)phosphine [(TMS) 3 P], attributed to the process of "self-focusing of size distribution" and enhanced reactivity of In-oleate through coordination with TOP. During growth, the processes of size focusing and defocusing are modulated by the accumulation of oleic acid and TOP molecules, as well as the amount of (TMS) 3 P in the growth precursor, which may relate to the dissolution process of InP magic size clusters. Through precise control, the best valley/depth ratio of InP QDs was 0.52 at the first absorption peak at 571 nm, resulting in luminescence with a full width at half-maximum of 35 at 620 nm with an absolute photoluminescence quantum yield around 90% after heteroepitaxial growth with ZnSe and ZnS shells.

Synthesis and Single Crystal X-ray Diffraction Structure of an Indium Arsenide Nanocluster

“…The one to three equivalent window is no longer appropriate for indium phenylacetate, and instead, we find that not only does one equivalent of phosphine promote the best cluster growth, but three equivalents of phosphine results in no cluster evolution. This difference in phosphine requirement between carboxylates is likely a function of the phosphine-bound indium carboxylate precursor speciation, which has been found to vary with phosphine concentration. , We, therefore, suggest that while rigid ligands such as phenylacetate allow for structural determination through single-crystal growth as described below, the most robust InAs cluster syntheses are those that are heavily modulated by hindering the diffusion of As­(SiMe 3 ) 3 using long chain fatty acids.…”

Enhanced Surface Passivation of InP/ZnSe Quantum Dots by Zinc Acetate Exposure

“…Common approaches to synthesize InP-based QDs either make use of tris­(trimethylsilyl)­phosphine [P­(SiMe 3 ) 3 ] ,− or aminophosphine, such as tris­(diethyl)­aminophosphine [P­(NEt 2 ) 3 ], − as the phosphorus precursor. QDs synthesized with P­(SiMe 3 ) 3 typically exhibit slightly narrower emission lines, probably reflecting an improved size dispersion, , while the aminophosphine route is more cost-effective and safer in use . Utilizing aminophosphines, we previously reported the formation of InP/Zn­(Se,S)/ZnS core/shell/shell QDs with a PLQY exceeding 90% across the visible spectrum from blue/cyan to red .…”

Potassium Iodide Doping for Vacancy Substitution and Dangling Bond Repair in InP Core-Shell Quantum Dots

“…A high lattice covalency of InP-based QDs inherently requires a high growth temperature (i.e., >300 °C) and a reactive P 3− precursor (i.e., tris(trimethylsilyl) phosphine; (TMS) 3 P) [ 10 , 47 , 50 , 51 , 52 , 53 , 54 , 55 ]. InP-based QDs grown at a high temperature exhibit internal defects such as vacancies in the InP core QDs (i.e., In − vacancies ( V In − ) and P + vacancies ( V P + ) in the core QDs) during nucleation and growth [ 56 , 57 , 58 ], resulting in a low PLQY and wide FWHM [ 53 , 59 , 60 , 61 , 62 ]. Recent advancements in doping methods for InP QDs have shown promising improvements in their optical properties.…”