Solid-structured phosphine sulfide as a new precursor in the synthesis of mercury sulfide quantum dots

Tricyclohexylphosphine sulfide (Cy)3PS, a solid-structured phosphine sulfide precursor, was used for the first time in the synthesis of sphere-shaped colloidally stable β-HgS CQDs. DFT calculations applying the TPSS-D3/def2-TZVP level of theory in the gas phase showed that the chemical reactivity of the titled precursor is similar to that of TOPS. The nanocrystals produced using HgCl2/(Cy)3PS/THF were colloidally stable, possessing near- and mid-infrared absorptions. As the reaction time increased, the first excitonic peaks were redshifted in the near-infrared window between 0.8 and 1.1 µm. Meanwhile, the red shifting of the mid-wavelength intraband (1Se‐1Pe) absorption peaks was between 3.9 and 4.8 µm. A good agreement between the diameters calculated using the atomistic tight-binding approach and those obtained using TEM was observed. The concentration and molar absorption coefficient (ε400) of the prepared QDs were determined as well. An increase in the ε400 of the quantum dots with increasing reaction time was shown. XPS elemental analysis showed that HgS NCs with a nearly equal atomic ratio of Hg:S were poorly colloidally stable, and their FT-IR spectra had no intraband absorptions in the mid-IR window. Meanwhile, high colloidally stable and mid-wavelength intraband absorption peaks in the FT-IR spectra were shown for mercury-rich HgS CQDs.