The duplicity of important documents has emerged as a serious problem worldwide. Therefore, many efforts have been devoted to developing easy and fast anticounterfeiting techniques with multicolor emission. Herein, we report the synthesis of multicolor luminescent lanthanide-doped YO nanorods by hydrothermal method and their usability in designing of unclonable security codes for anticounterfeiting applications. The spectroscopic features of nanorods are probed by photoluminescence spectroscopy. The YO:Eu, YO:Tb, and YO:Ce nanorods emit hypersensitive red (at 611 nm), strong green (at 541 nm), and bright blue (at 438 nm) emissions at 254, 305, and 381 nm, respectively. The SEM and TEM/HRTEM results reveal that these nanorods have diameter and length in the range of 80-120 nm and ∼2-5 μm, respectively. The two-dimensional spatially resolved photoluminescence intensity distribution in nanorods is also investigated by using confocal photoluminescence microscopic technique. Further, highly luminescent unclonable security codes are printed by a simple screen printing technique using luminescent ink fabricated from admixing of lanthanide doped multicolor nanorods in PVC medium. The prospective use of these multicolor luminescent nanorods provide a new opportunity for easily printable, highly stable, and unclonable multicolor luminescent security codes for anti-counterfeiting applications.

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The semiconducting compound CuGax I n~_xSe2 crystallizes in the chalcopyrite structure (space group

An electron beam evaporation method is used to prepare In2O3 films with and without Sn doping. It is shown that highly transparent and conducting films can be prepared at substrate temperature as low as 200 degrees C. The characteristic feature of such films is their high carrier density and high infrared reflectivity. The lowest resistivity is found to be 2.4*10-4 Omega cm with a carrier concentration of 8*1020 cm-3 and mobility of about 30 cm2 V-1 s-1 at the doping level of 4 mol.% SnO2. These polycrystalline films show a highly preferred orientation. On the basis of Hall measurements and structural data, sources of scattering in these films are suggested.