title: Brightly luminescent organically capped silicon nanocrystals fabricated at room temperature and atmospheric pressure.
abstract: Silicon nanocrystals are an extensively studied light-emitting material due to their inherent biocompatibility and compatibility with silicon-based technology. Although they might seem to fall behind their rival, namely, direct band gap based semiconductor nanocrystals, when it comes to the emission of light, room for improvement still lies in the exploitation of various surface passivations. In this paper, we report on an original way, taking place at room temperature and ambient pressure, to replace the silicon oxide shell of luminescent Si nanocrystals with capping involving organic residues. The modification of surface passivation is evidenced by both Fourier transform infrared spectroscopy and nuclear magnetic resonance measurements. In addition, single-nanocrystal spectroscopy reveals the occurrence of a systematic fine structure in the emission single spectra, which is connected with an intrinsic property of small nanocrystals since a very similar structure has recently been observed in specially passivated semiconductor CdZnSe nanoparticles. The organic capping also dramatically changes optical properties of Si nanocrystals (resulting ensemble photoluminescence quantum efficiency 20%, does not deteriorate, radiative lifetime 10 ns at 550 nm at room temperature). Optically clear colloidal dispersion of these nanocrystals thus exhibits properties fully comparable with direct band gap semiconductor nanoparticles.
authors.affiliation: Institute of Physics of the ASCR, vvi, Cukrovarnicka 10, 162 53 Prague 6, Czech Republic. kusova@fzu.cz
authors.forename: Katerina
authors.initials: K
authors.lastname: Kůsová
authors.forename: Ondrej
authors.initials: O
authors.lastname: Cibulka
authors.forename: Katerina
authors.initials: K
authors.lastname: Dohnalová
authors.forename: Ivan
authors.initials: I
authors.lastname: Pelant
authors.forename: Jan
authors.initials: J
authors.lastname: Valenta
authors.forename: Anna
authors.initials: A
authors.lastname: Fucíková
authors.forename: Karel
authors.initials: K
authors.lastname: Zídek
authors.forename: Jan
authors.initials: J
authors.lastname: Lang
authors.forename: Jirí
authors.initials: J
authors.lastname: Englich
authors.forename: Pavel
authors.initials: P
authors.lastname: Matejka
authors.forename: Petr
authors.initials: P
authors.lastname: Stepánek
authors.forename: Snejana
authors.initials: S
authors.lastname: Bakardjieva
mesh_terms: D001274:Atmospheric Pressure; D003102:Colloids; D008027:Light; D008163:Luminescent Measurements; D009682:Magnetic Resonance Spectroscopy; D046529:Microscopy, Electron, Transmission; D053758:Nanoparticles / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods*; D012542:Scattering, Radiation; D012825:Silicon / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties; D013696:Temperature
chemical_list: D003102:Colloids; D012825:Silicon