Twin-Tail Surfactant Peculiarity in Superficial Fabrication of Semiconductor Quantum Dots: Toward Structural, Optical, and Electrical Features

Abstract

A solitary tread hydrothermal synthesis of lead telluride (PbTe) and copper telluride (Cu_{(2–<i>x</i>)}Te) nanoparticles (NPs) at 150 °C was carried out using cationic twin-tail surfactant (TTS) dimethylenebis­(dodecyldimethylammonium bromide) (12-2-12) as a capping agent. UV–vis and X-ray diffraction (XRD) have been employed to elaborate about structural and physicochemical aspects of NPs. The morphology and the capping behavior have been revealed through scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM). Electron micrographs clearly demonstrated the formation of cubic shaped PbTe NPs with average size distribution ≅ 20 ± 5 nm. A perversely spherical morphology has been observed for Cu_{(2–<i>x</i>)}Te NPs with average size ≅15 ± 6 nm. The interactions of the adsorbed capping surfactant TTS on the metal surface and alignment of the molecules were confirmed from FTIR studies. The crystallite sizes and lattice strain on the peak broadening of the NP have been measured using Williamson–Hall analysis and the size–strain plot method. The optical band gap energy of NP, as determined from the absorbance spectrum, was 0.5 eV for lead telluride, while that for copper telluride was 3.4 eV owing to quantum confinement driven shift from bulk materials to nanoscale. The electrical conductivity of lead telluride and copper telluride was found to be 0.01–0.07 and 2.18–10.1 S cm^–1, respectively