Size and emission color tuning in the solution phase synthesis of highly luminescent germanium nanocrystals

Efficient one-pot synthesis of monodisperse alkyl-terminated colloidal germanium nanocrystals

“…The peaks between 2855 and 2956 cm -1 are attributed to the CH 2 and CH 3 stretching modes of the alkyl group (Silverstein et al 1991). The peaks at 1465 and 1260 cm -1 are ascribed to the scissoring and bending of the Ge-C and Ge-CH 2 bonds, respectively, while the strong peak at 1375 cm -1 is assigned to the C-CH 3 symmetric stretching mode (Carolan and Doyle 2014;Socrates 1980). The peak at 964 cm -1 is assigned to the Ge-O-Ge vibrations (Henderson et al 2010), while the peaks below 900 cm -1 are a combination of the Ge-O and the Ge-C stretching modes (Taylor et al 1999), consistent with a covalently attached alkyl layer with some surface oxidation.…”

“…The underlying mechanism for PL in Ge NCs is usually described either in terms of exciton recombination confined entirely within the nanocrystal core, or a surface chemistry model that emphasizes the importance of energy states at the NC surface (Carolan and Doyle 2014;Vaughn II and Schaak 2013;Dasog et al 2013). The PL spectra shown in Fig.…”

“…This approach, first reported by Wilcoxon et al for the preparation of hydride terminated NCs (Wilcoxon et al 2001), was later adapted using either thermally activated or Pt-catalysed hydrogermylation reactions to form alkyl-and amineterminated NCs with covalent Ge-C surface bonds (Carolan and Doyle 2014;Fok et al 2004;Prabakar et al 2010). Despite the successes of the microemulsion synthetic approach for preparation of high quality, size monodisperse Ge NCs, the post synthetic purification remains lengthy, while the Pt catalyst used is toxic to cells ).…”

Germanium nanocrystals as luminescent probes for rapid, sensitive and label-free detection of Fe3+ions

“…43 Many groups also employ post synthetic purification techniques such as high performance liquid chromatography (HPLC), 33 column chromatography, 35,36 controlled etching, 44 size-selective precipitation using nonsolvents, 34,38,40,[45][46][47] or a combination of the above 48,49 to chemically purify and separate size monodisperse Ge NCs fractions. While chromatography and HPLC methods work well for size separation, the method is generally reported only for small samples, and the rate of production is slow compared to simple centrifugation methods.…”

“…A number of different solution phase approaches for synthesis of functionalised, luminescent Ge NCs have been reported, including the metathesis reaction of GeCl 4 with Zintl salts 27,28 and high temperature decomposition of organogermane precursors. 29,30 Other methods include thermal co-reduction of amido based precursors, 31 aqueous phase reduction of GeO 2 powders by NaBH 4 , 32 reduction of germanium halides [33][34][35][36][37] and other high temperature chemical reduction methods.…”