Microwave-assisted solution synthesized crystalline germanium nanoparticles

Colloidal germanium (Ge) nanocrystals (NC) are of great interest with possible applications for photovoltaics and near-IR detectors. In many examples of colloidal reactions, Ge(II) precursors are employed and NCs of diameter ~3 – 10 nm have been prepared. We have recently employed a two-step microwave-assisted reduction of GeI₄ in oleylamine (OAm) to prepare monodispersed Ge NCs with a size of 18.9 [endif]--> 1.84 nm. More importantly, the as-synthesized Ge NCs showed high crystallinity with single crystal nature as indicated by powder X-ray diffraction, selected area electron diffraction, and high-resolution transmission electron microscopy. Solutions involved in this two-step reaction were investigated with ¹H NMR spectroscopy and high-resolution mass spectrometry. One possible reaction pathway is proposed to unveil the details of the reaction involving GeI₄ and OAm. I will present new updates and insights gained with this chemical route that might impact the nanoparticle synthesis of other covalently bonding semiconductors.