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

Abstract

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 o-AgInS2 nanoparticles via the cation exchange and alloy process, and finally evolved into o-AgInS2@InSx 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 t-AgInS2/InSx nanoparticles. In addition, the photoluminescence quantum yield (PLQY) of t-AgInS2/InSx nanoparticles was higher than that of o-AgInS2@InSx nanoparticles.