Synthesis of light-coloured nanoparticles of wide band gap p-type semiconductors CuGaO2 and LaOCuS by low temperature hydro/solvothermal processes

We report here two original low temperature routes for the synthesis of nanostructured particles of p-type TCO's CuGaO2 and LaOCuS. Light grey CuGaO2 nanolayered particles (similar to 300 nm large and 5 nm thick) were prepared from a hydrothermal synthetic route using soluble hydrated metal nitrates as precursors and ethylene glycol (EG) as reducing agent. We found then that the initial pH of the precursor's solution is a key parameter to tune the particle sizes (from 2 tun to 300 nm) and subsequently the colour (from dark brown to light grey) of the CuGaO2 powder. LaOCuS was obtained for the first time as greyish nanolayered particles (similar to 100 nm large and 10 nm thick) via a solvothermal route in ethylene diamine with hydrate chloride lanthanum, copper mono oxide and elemental sulphur as precursors. We found that the control of the chloride lanthanum precursor hydration rate is of prime importance to achieve pure material and to tune the colour of the LaOCuS sample. Both CuGaO2 and LaOCuS nanolayered particles synthesized via these soft chemistry routes exhibit all the characteristics of transparent p-type semiconductors [GRAPHICS] . (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim