Novel single-molecule precursor routes for the direct synthesis of InS andInSe quantum dots

Nanoparticles of InS and InSe capped with TOPO (tri-n-octylphosphine oxide) or nanoparticles of InSe capped with 4-ethylpyridine, which are close to m ono-dispersed, have been prepared by a single-source route using tris(dieth yldithiocarbamato)indium(III) or tris(diethyldiselenocarbamato)indium(III), respectively. The nanoparticles of InS and InSe both show quantum size eff ects in their optical spectra and the photoluminescence (PL) spectra show b road emissions due to the surface traps. Substantial blue shifts in the ons et of absorption have been observed; 0.44 eV for InS and 1.60 eV for InSe. The X-ray diffraction (XRD) pattern of InS showed co-precipitation with TOP O and the crystalline particles turned powdery when studied by transmission electron microscopy (TEM). Selected area electron diffraction (SAED), X-ra y diffraction (XRD) and transmission electron microscopy (TEM) studies of t he InSe nanoparticles show the hexagonal phase in the size range 5.8-7.0 nm . The crystallinity of the InSe nanoparticles was also evident from high re solution transmission electron microscopy (HRTEM), which gave well defined images of nanosize particles with clear lattice fringes.