Systematic synthesis of different-sized AgInS2/GaS x nanocrystals for emitting the strong and narrow excitonic luminescence

Abstract

This paper presents for the first time the systematic synthesis of AgInS2 (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 Ag2S NCs and then (ii) partial exchange of Ag+ with In3+ in the template Ag2S NCs. For step (i), Ag2S 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 In3+ at 120 °C for 60 min. Finally, GaS x was shelled on AIS core NCs to produce the AgInS2/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.