Study of phosphine tellurides as precursors in the synthesis of HgTe CQDs for IR applications

Mercury telluride colloidal quantum dots are considered the ideal nanomaterial for infrared applications [1]. The nearly zero band gap energy of bulk mercury telluride and the quantum confinement effect allowed us to prepare HgTe CQDs with absorption that covers all infrared windows [2]. The importance of infrared technology was observed in several applications, such as medical imaging, infrared lasers, sensors, and detectors [2-4]. Tri-octylphosphine telluride (TOPTe) is the most common precursor used in the synthesis of HgTe colloidal quantum dots (CQDs) [5]. The weak stability of TOPTe towards dissociation compared to TOPS and TOPSe motivated scientists to explore new tellurium precursors [6]. Tris(dimethylamino)phosphine telluride (Me₂N)₃PTe is a new tellurium precursor that was used in the synthesis of CdTe nanocrystals. [6]. In this work, we report the study of several phosphine tellurides in the preparation of HgTe CQDs. The efficient synthesis and characterization of HgTe CQDs were developed for the first time by applying TDMAPTe/THF and mercury chloride (HgCl₂) precursors. The preparation was conducted by organometallic hot – injection route. Transmission electron microscopy (TEM), SAED analysis, X-ray photoelectron spectroscopy, UV-Vis-NIR spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), and Raman spectroscopy were employed in the characterization of obtained nanocrystals. The comparison between TDMAPTe and TOPTe precursors revealed that the first one has a higher chemical reactivity. The band edge peak of the prepared nanocrystals was at 1296.5 nm after 15 min of reaction time with narrow size distribution (FWHM = 213.93 nm). The first absorption peak red-shifted to 1335.5 nm after 60 min and no significant red-shift was observed.