Robust B-exciton emission at room temperature in few-layers of MoS2:Ag nanoheterojunctions embedded into a glass matrix

Abstract

Tailoring the photoluminescence (PL) properties in two-dimensional (2D) molybdenum disulfide (MoS2) crystals using external factors is critical for its use in valleytronic, nanophotonic and optoelectronic applications. Although significant effort has been devoted towards enhancing or manipulating the excitonic emission in MoS2 monolayers, the excitonic emission in few-layers MoS2 has been largely unexplored. Here, we put forward a novel nano-heterojunction system, prepared with a non-lithographic process, to enhance and control such emission. It is based on the incorporation of few-layers MoS2 into a plasmonic silver metaphosphate glass (AgPO3) matrix. It is shown that, apart from the enhancement of the emission of both A- and B-excitons, the B-excitonic emission dominates the PL intensity. In particular, we observe an almost six-fold enhancement of the B-exciton emission, compared to control MoS2 samples. This enhanced PL at room temperature is attributed to an enhanced exciton–plasmon coupling and it is supported by ultrafast time-resolved spectroscopy that reveals plasmon-enhanced electron transfer that takes place in Ag nanoparticles-MoS2 nanoheterojunctions. Our results provide a great avenue to tailor the emission properties of few-layers MoS2, which could find application in emerging valleytronic devices working with B excitons.

Electrostatic control of photoluminescence from A and B excitons in monolayer molybdenum disulfide

“… 27 Sarkar et al obtained a six-fold enhancement of the intrinsically weak B excitonic emission in few layers of MoS 2 : Ag nano-heterojunctions embedded into a glass matrix, which can be attributed to the dipole–dipole interactions via exciton–plasmon coupling at room temperature. 28 The simultaneous tailoring of emission form both A excitons and B excitons remains largely unexplored.…”

Graphene-Coated Substrate-Mediated Photoresponse from MoS2/UCNP Nanohybrid-Based Photodetectors

“…The two characteristic excitonic peaks of MoS 2 are observed near 612 (B-exciton) and 675 nm (A-exciton) (Figure 2a). 46 The 980 nm absorption band of the Yb-doped UCNP is obscure due to its low concentration in the NC. However, the 980 nm characteristic peak shows up when enlarged (inset, Figure 2a).…”

“…The UV–vis absorption spectroscopy of individual MoS 2 , UCNPs, and MoS 2 -UCNPs NC dispersed in NMP is shown in Figure a. The two characteristic excitonic peaks of MoS 2 are observed near 612 (B-exciton) and 675 nm (A-exciton) (Figure a) . The 980 nm absorption band of the Yb-doped UCNP is obscure due to its low concentration in the NC.…”

Advanced composite glasses with metallic, perovskite, and two-dimensional nanocrystals for optoelectronic and photonic applications

“…By coupling 2D MoS 2 with nanomaterials it is possible to manipulate its PL, although there isn't a great amount of research regarding few-layer MoS 2 . A recent study by Sarkar et al 111 provides a novel synthetic route for the incorporation of MoS 2 flakes inside a silver metaphosphate (AgPO 3 ) glass (Fig. 10d).…”

“…10d. 111 Several drops of an as-prepared MoS 2 /isopropanol solution were dropcast on the glass substrate. Following this, the glass was heated to 170 °C, gained viscosity, and allowed the immersion of the 2D crystals beneath the surface, i.e.…”