Ligands Induced the Growth of Colloidal AgInS₂ Nanoparticles with Tuned Structure and Photoluminescence Property

Understanding the growth mechanism of AgInS₂ nanoparticles could benefit the designed growth of I-III-VI₂ nanomaterials and their applications in photonics, optoelectronics, etc. Herein, using tris(dibutyldithiocarbamate) indium(III) [In((C₄H₉)₂NCS₂)₃] ([InR₃]) and dibutyldithiocarbamate silver(I) [Ag((C₄H₉)₂NCS₂)] ([AgR]) precursors, AgInS₂-based nanoparticles with different structures have been synthesized in a controlled manner through a one-pot approach via different growth mechanisms in 1-dodecanethiol (DDT) and oleylamine (OLA), respectively. The DDT and OLA could participate in the decomposition of precursors; thus, the [AgR]/DDT, [InR₃]/DDT, [AgR]/OLA, and [InR₃]/OLA were used herein to describe the decomposition steps. In DDT, the decomposition activity of [AgR]/DDT was much higher than that of [InR₃]/DDT; thus, the sequential decomposition of [AgR]/DDT and [InR₃]/DDT led to the formation of the Ag₂S nanoparticles intermediate first, which then reacted with [InR₃]/DDT to form metastable <i>o</i>-AgInS₂ nanoparticles via the cation exchange and alloy process, and finally evolved into <i>o</i>-AgInS₂@InS_<i>x</i> core@shell nanoparticles, while in OLA, the decomposition activity of [AgR]/OLA was slightly higher than that of [InR₃]/OLA. Thus, the quasi-co-decomposition of [AgR]/OLA and [InR₃]/OLA led to the formation of Ag-rich Ag-In-S amorphous nanoparticles intermediate first and then quickly evolved into stable <i>t</i>-AgInS₂/InS_<i>x</i> nanoparticles. In addition, the photoluminescence quantum yield (PLQY) of <i>t</i>-AgInS₂/InS_<i>x</i> nanoparticles was higher than that of <i>o</i>-AgInS₂@InS_<i>x</i> nanoparticles.