Nonvolatile Memristive Devices Based on In Situ Functionalized Layered rGO-MoS₂ Nanocomposites

Abstract

Hybrid composites comprised of layered two-dimensional (2D) materials have attracted growing attention, especially in large-area electronics. Herein, we exploit the synergistic interfacial effect of molybdenum disulfide (MoS2) grafted reduced graphene oxide (rGO) and study the memristive characteristics of the layered hybrid rGO-MoS2 nanocomposites (NCs). The synthesized materials are analyzed using optical, structural, elemental, and morphological techniques. The average number of layers (~ 6 to 10) is estimated from the intense X-ray diffraction peak of the polycrystalline materials. The intercalation of rGO in the rGO-MoS2 NCs results in an increased energy bandgap compared to pristine MoS2. The photoluminescence study exhibits dominant blue emission due to the restoration of the sp2-hybridized carbon domain in the reduced sheets. The surface topography of the NCs shows a 3D flower-like structure with multiple nano-petals interconnected in the form of nanosheets. The average diameter of the flower-shaped particles is calculated to be ~258 and ~301 nm for MoS2 and rGO-MoS2, respectively. The crossbar devices (ITO/rGO-MoS2/Cu) in a sandwich configuration (thickness ~700 nm) are fabricated, displaying stable and repeatable bipolar resistive switching characteristics. The trapping and de-trapping of the charge carriers at the rich sulfur vacancies are responsible for bipolar memory behavior.

MoS2-functionalized conductive carbon heterostructure embedded with ferroelectric polymers for bipolar memristive applications

“…The presence of GO acts as a novel support material for mediating nucleation and selective growth of MoS 2 . Subsequently, the growth of MoS 2 takes place via a strong van der Waals interaction between the oxygen functional groups and Mo precursors [15]. A similar method was implemented for the synthesis of pristine MoS 2 only without the addition of GO solution.…”

“…The characteristic peaks of PVDF and polymer blend disappear due to dominating features (∼274 nm) of the reinforced counterparts in the rGO-embedded polymer matrix (figure S1(b)). The restoration of electronic conjugation in rGO after the deoxygenation process results in an absorption peak shift towards 269 nm compared to pristine GO [15,37]. Pristine MoS 2 (figure 1(a)) exhibits broad absorption peaks, stretching from the UV to the visible region, positioned at 413 (doublet), 615, and 670 nm.…”

“…The TEM image of the rGO-MoS 2 nanohybrid (figure 5(a)) exhibits large-area crumpled sheets of rGO with wrinkles decorated with MoS 2 nanoflakes [51]. The residual hydrophilic groups (-OH or -COOH) at the edges and basal plane of the rGO sheets make it possible for both the inorganic counterparts (S, Mo) to attach onto it and further act as nucleation sites for the growth of MoS 2 [15]. Therefore, the grown MoS 2 nanoflakes are well interspersed and grafted on both sides of the layered rGO sheets, giving rise to sandwich heterostructures.…”

“…Transition metal dichalcogenides (TMDCs) belong to the class of 2D family with the general chemical formula (MX 2 , M: metal, X: chalcogenide) and found diverse applications in electrocatalysis [9], hydrogen evolution reaction [10], lithium storage [11], supercapacitors [12], sodium-ion batteries [13], photocatalysis [14], resistive memory [15], etc. In particular, the molybdenum disulfide (MoS 2 ) is a widely researched TMDC due to its layer-dependent controllable electronic and optoelectronic characteristics [16].…”

“…Das et al [15] have found sulfur vacancy-mediated bipolar RS characteristics in rGO-MoS 2 nanohybrid and obtained an I ON /I OFF ratio of ∼10 2 . In another work, Das et al reported GOQDs: polyvinyl alcohol (PVA)-based device that exhibits write-once-read-many (WORM) behavior with a decent I ON /I OFF ratio [25].…”