Systematic synthesis of different-sized AgInS 2 /GaS x nanocrystals for emitting the strong and narrow excitonic luminescence.

This paper presents for the first time the systematic synthesis of AgInS 2 (AIS) nanocrystals (NCs) with different sizes of 2.6-6.8 nm just by controlling only the reaction temperature. The synthesis of AIS core NCs was carried out in 2 steps: (i) synthesis of Ag 2 S NCs and then (ii) partial exchange of Ag + with In 3+ in the template Ag 2 S NCs. For step (i), Ag 2 S NCs of different sizes were synthesized by reaction of the Ag and S precursors at different temperatures of 30 °C to 130 °C, for the same reaction time of 30 min. For step (ii), AIS NCs were created by the exchange of Ag + with In 3+ at 120 °C for 60 min. Finally, GaS x was shelled on AIS core NCs to produce the AgInS 2 /GaS x core/shell structures. The synthesized AIS/GaS x NCs demonstrate the clear excitonic absorptions and strong, narrow excitonic luminescence peaking at 530-606 nm depending on the size of AIS core NCs.