Synthesis of Near-Infrared Emissive InAs/InP/ZnSe from Low Toxicity Precursors
Author: Marcello Garbo
Faculty Supervisor: Michael Enright
Department: Chemistry & Biochemistry
The most developed approaches for the synthesis of InAs core/shell/shell nanocrystals (NCs) rely on pyrophoric, toxic, and extremely reactive tris-trimethylsilyl (or tris-trimethylgermil) arsine and phosphine precursors. Less toxic and commercially available reagents, such as tris(dimethylamino)arsine and tris(dimethylamino)phosphine have recently emerged as alternative precursors for InAs and InP synthesis respectively. However, InAs/InP/ZnSe core/shell/shell nanocrystals made from these materials require further optimization to turn on and improve luminescence. This is due to a multitude of factors including polydisperse size distributions, poorly defined optical properties, and inhomogeneous shell encapsulation to remove InAs and InP surface defects. Here, we investigate the shelling dynamics of tris(dimethylamino)phosphine for the creation of an InP shell on InAs NCs made using tris(dimethylamino)arsine. Creating a uniform InP intermediate shell is crucial due to the lattice mismatch between InAs and ZnSe. This enables the construction of a core/shell/shell system where the InP shell minimizes the lattice mismatch between the InAs core and the outermost ZnSe shell, leading to enhanced photoluminescence quantum yield. These fully RoHS compliant heterostructures have potential applications in solar harvesting and in the medical field as near-infrared fluorescent tags for imaging.