Monodispersed cation-disordered cubic AgInS2 nanocrystals with enhanced fluorescence

Monodispersed metastable cubic ${\text{AgInS}}_2$ nanocrystals with an average size of around 2.5 nm are obtained via a solution-phase reaction. In contrast with the usual chalcopyrite and orthorhombic phase, ${\text{Ag}}^{+}$ and ${\text{In}}^{3+}$ cations in metastable cubic ${\text{AgInS}}_2$ are randomly coordinated by four ${\text{S}}^{2-}$ anions. A phase transition from cation-disordered cubic to orthorhombic ${\text{AgInS}}_2$ occurs with the increased reaction temperature or elongated reaction time. The photoluminescence quantum yield of cation-disordered cubic ${\text{AgInS}}_2$ nanocrystals could reach 10% at room temperature, which is much higher than that of orthorhombic ${\text{AgInS}}_2$ nanocrystals obtained via a similar approach.