Highly Fluorescent, Near-Infrared-Emitting Cd²⁺-Tuned HgS Nanocrystals with Optical Applications

Abstract

Bulk HgS itself has proven to be a technologically important material; however, the poor stability and weak emission of HgS nanocrystals have greatly hindered their promising applications. Presently, a critical problem is the uncontrollable growth of HgS NCs and their intrinsic surface states which are susceptible to the local environment. Here, we address the issue by an ion-tuning approach to fabricating stable, highly fluorescent Cd:HgS/CdS NCs for the first time, which efficiently tuned the band-gap level of HgS NCs, pushing their intrinsic states far away from the surface, reducing the strong interaction of the environment with surface states and hence drastically boosting the exciton transition. As compared to bare HgS NCs, the obtained Cd:HgS/CdS NCs exhibited tunable luminescence peaks from 724 to 825 nm with an unprecedentedly high quantum yield up to 40% at room temperature and excellent thermal and photostability. Characterized by TEM, XRD, XPS, and AAS, the resultant Cd:HgS/CdS NCs possessed a zinc-blende structure and was composed of a homogeneous alloyed HgCdS structure coated with a thin-layer CdS shell. The formation mechanism of Cd:HgS/CdS NCs was proposed. These bright, stable HgS-based NCs presented promising applications as fluorescent inks for anticounterfeiting and as excellent light converters when coated onto a blue-light-emitting diode.

Biosynthesis of micro‐ and nanocrystals of Pb (II), Hg (II) and Cd (II) sulfides in four Candida species: a comparative study of in vivo and in vitro approaches

“…Furthermore, it has also been reported that HgS NCs are technologically important materials (Jeong et al, 2014). However, their instability has hampered their usefulness (Yang et al, 2015). NCs chemically synthesized from Cd:HgS/CdS have proved to be stable and highly fluorescent compared with the HgS NCs also obtained by chemical synthesis (Yang et al, 2015).…”

“…However, their instability has hampered their usefulness (Yang et al, 2015). NCs chemically synthesized from Cd:HgS/CdS have proved to be stable and highly fluorescent compared with the HgS NCs also obtained by chemical synthesis (Yang et al, 2015). Other research groups have used other synthesis strategies for AgS NCs, but all with a high degree of complexity Jeong et al, 2014).…”

HgSe/CdE (E = S, Se) Core/Shell Nanocrystals by Colloidal Atomic Layer Deposition

“…As ZnTe is prone to oxidation and often leads to core/shell QDs with a staggered band alignment, we consider CdSe and CdS to be the most interesting materials for shell growth around HgSe QDs. However, the tendency of mercury and cadmium chalcogenides to form solid solutions rather than phase separated core/shell structures can compromise the formation of such HgSe/CdE (E = S, Se) core/shell QDs by a mere duplication of established shelling reactions. − This may in part explain why all the above-discussed procedures involve room temperature or close-to room temperature reactions.…”

Emission Color Tuning and White Light Generation from a Trimolecular Cocktail in Cationic Micellar System with Promising Applicability in the Anticounterfeiting Technology

“…By the virtue of their anticounterfeiting features, such systems are vital in catering to the problems faced globally while concerning human health, the economy, and national security. For example, consumer goods, medicines, and even the important electronic gadgets of security forces that are used to secure the nation are not fully anticounterfeitable. − The low security in the anticounterfeiting systems, which is usually due to the restricted response of the system toward either a single stimulus (single-level) or a maximum of two stimuli (two-level), poses a major challenge in the current advanced materials for their undefeatable applications in the anticounterfeiting technology. Therefore, designing multilevel authentication systems via multiresponsiveness of a single formulation being a cocktail of suitable materials could be an applicable solution for this issue.…”