From Indium-Doped Ag₂S to AgInS₂ Nanocrystals: Low-Temperature In Situ Conversion of Colloidal Ag₂S Nanoparticles and Their NIR Fluorescence

Focusing on ternary I-III-VI₂ colloidal nanocrystals (NCs) synthesized with precise control of the composition (from doping to ternary composition) and NIR fluorescence performance, monodisperse binary In³⁺-doped Ag₂S NCs and ternary AgInS₂ NCs have been achieved successfully by facile low-temperature in situ conversion of colloidal Ag₂S nanoparticles. In³⁺ ions were inserted into the crystal lattice of Ag₂S NCs at a relatively low temperature as dopant and ternary AgInS₂ NCs were obtained at a higher temperature following a phase transition. These doped Ag₂S and AgInS₂ NCs based on different indium precursor concentrations were explored with respect to the position and intensity of the near-infrared photoluminescent emission at different doping levels and crystal phase evolution.