Facile Synthesis of Cadmium-Free Zn-In-S:Ag/ZnS Nanocrystals for Bio-Imaging

Abstract

High quality cadmium-free Zn-In-S:Ag doped-nanocrystals (d-NCs) were synthesized via a simple one-step noninjection route using silver nitrate, indium acetate, zinc acetate, oleylamine, S powder and 1-dodecanethiol as starting materials in an organic phase. The size and optical properties can be effectively tailored by controlling the reaction time, reaction temperature, Ag+ dopant concentration, and the molar ratio of In to Zn. The photoluminescence wavelength of as-prepared Zn-In-S:Ag NCs covered a broad visible range from 458 nm to 603 nm. After being passivated by protective ZnS shell, the photoluminescence quantum yield (PLQY) of Zn-In-S:Ag+ /ZnS was greatly improved to 43.5%. More importantly, the initial high PLQY of the obtained core/shell d-NCs in organic media can be preserved when being transferred into the aqueous media via ligand exchange. Finally, high quality Zn-In-S:Ag+ /ZnS d-NCs in aqueous phase were applied as bio-imaging agents for identifying living KB cells.

From Red to Green Luminescence via Surface Functionalization. Effect of 2-(5-Mercaptothien-2-yl)-8-(thien-2-yl)-5-hexylthieno[3,4-c]pyrrole-4,6-dione Ligands on the Photoluminescence of Alloyed Ag–In–Zn–S Nanocrystals

“…This type of research is highly desirable in the case of quaternary Ag–In–Zn–S nanocrystals, especially, because by changing their composition it is possible to tune their efficient luminescence over the whole visible spectral range. This strongly facilitates their application in electronics − and biomedical sciences. − The analysis of ligand exchange-induced photoluminescence changes is especially important in this respect. In the case of binary CdSe nanocrystals the luminescence is governed by the classical radiative recombination mechanism 1S­(e) → 1S­(h).…”

Full‐visible spectrum emitting Zn–In–S:Cu/ZnS nanocrystals based on varying Cu concentrations and its application in white LEDs

“…It can be clearly noticed that PL intensity d‐NCs/silicone resin composite only declines by about 10% after it was continuously irradiated for 4 hours under ultraviolet light (Figure A), while a slight enhancement is observed for Zn–In–S:Cu/ZnS d‐NCs (Figure B). This slight enhancement should be ascribed to the NCs surface oxidation caused by UV irradiation, which is known for the NCs surface passivation . It simultaneously indicates an excellent photostability of as‐prepared core/shell d‐NCs.…”

“…This slight enhancement should be ascribed to the NCs surface oxidation caused by UV irradiation, which is known for the NCs surface passivation. 29,46 It simultaneously indicates an excellent photostability of as-prepared core/shell d-NCs. Increasing temperature, both PL intensities of d-NCs/silicone resin composite and d-NCs decrease slowly, and at 80°C, their emission intensities preserve above 78% of the initial ones ( Figure 6,D).…”

“…In the previous work of our group, Ag‐doped Zn–In–S have successfully synthesized . The full spectrum emission from 458 to 603 nm can be obtained by adjusting the reaction temperature, time, Ag doping concentration, and the ratio of In/Zn.…”

“…In the previous work of our group, Ag-doped Zn-In-S have successfully synthesized. 29 The full spectrum emission from 458 to 603 nm can be obtained by adjusting the reaction temperature, time, Ag doping concentration, and the ratio of In/Zn. The highest QY of 43.5% is available as the emission wavelength located at 526 nm after growing a ZnS shell around Zn-In-S:Ag d-NCs.…”