ИСТИНА

Nanocrystals (NCs) were synthesized from cadmium oleate and trioctylphosphine selenide (TOPSe) in diphenyl ether at 200°C. Before injection of TOPSe we added Ag precursor and TOP, required for its solution. The composition of purified NCs was studied by X-ray fluorescence spectroscopy, size distribution and morphology were obtained from TEM. Absorption and photoluminescence spectra were measured. The studies included the following precursors: AgF, AgCl, AgBr, AgI, with the molar ratio of Ag to Cd from 1:10 to 1:1. At high doping levels we observed formation of large NCs with “band-edge” luminescence peaked at 1.78-1.90 eV. Also an intensive two-peaked IR-luminescence band appeared, with maxima at 1.3-1.4 eV. Its intensity was only low upon AgF usage. When employing AgBr this band widens, reaching the “band-edge” peak. Despite their large size, close to 2 Bohr radii, compact NCs have a good quantum yield. In case of AgCl precursor, the obtained NCs are extremely gaunt (up to 150 nm) and branched with poor quantum yield. Highest doping level reached was 18 at.% Ag to Cd. Aging of samples was investigated.