Single-source precursor synthesis of quinary AgInGaZnS QDs with tunable photoluminescence emission

A single source molecular precursor synthesis of new quinary Ag-In-Ga-Zn-S (AIGZS) QDs is presented. Dithiocarbamate complexes with varied Ag/In/Ga/Zn ratios were prepared from AgNO3, In(NO3)3, Ga(NO3)3 and Zn(diethyldithiocarbamate)2. The thermal decomposition of these complexes at 220°C in oleylamine produces AIGZS QDs emitting from the visible to the near-infrared region and with photoluminescence quantum yields (PL QYs) up to 48.3%. For AIGZS QDs prepared with a (Ag + In + Ga)/Zn molar ratio of 1, intragap states likely involving Ag + ions are responsible of the PL emission and the PL lifetime could reach 278 ns. A marked increase of the PL lifetime (up to 915 ns) was observed when decreasing the (Ag + In + Ga)/Zn molar ratio to 0.5. The optical properties of AIGZS QDs could be maintained after transfer in aqueous solution. AIGZS should be of high potential for various applications due to their PL emission tunability and high PL QYs.