The mechanism of the modulation of electronic anisotropy in two-dimensional ReS2

Study on interface engineering and chemical bonding of the ReS2@ZnO heterointerface for efficient charge transfer and nonlinear optical conversion efficiency

Rhenium sulfide (ReS2) has emerged as a promising two-dimensional material, demonstrating broad-spectrum visible absorption properties that make it highly relevant for diverse optoelectronic applications. Manipulating and optimizing the pathway of photogenerated carriers play a pivotal role in enhancing the efficiency of charge separation and transfer in novel semiconductor composites. This study focuses on the strategic construction of a semiconductor heterostructure by synthesizing ZnO on vacancy-containing ReS2 (VRe-ReS2) through chemical bonding processes. The ingeniously engineered built-in electric field within the heterostructure effectively suppresses the recombination of photogenerated electron-hole pairs. A direct and well-established interfacial connection between VRe-ReS2 and ZnO is achieved through a robust Zn-S bond. This distinctive bond configuration leads to enhanced nonlinear optical conversion efficiency, attributed to shortened carrier migration distances and accelerated charge transfer rates. Furthermore, theoretical calculations unveil the superior chemical interactions between Re vacancies and sulfide moieties, facilitating the formation of Zn-S bonds. The photoluminescence (PL) intensity is increased by the formation of VRe-ReS2 and ZnO heterostructure and the PL quantum yield of VRe-ReS2 is improved. The intricate impact of the Zn-S bond on the nonlinear absorption behavior of the VRe-ReS2@ZnO heterostructure is systematically investigated using femtosecond Z-scan techniques. The charge transfer from ZnO to ReS2 defect levels induces a transition from saturable absorption to reverse saturable absorption in the VRe-ReS2@ZnO heterostructure. Transient absorption measurements further confirm the presence of the Zn-S bond between the interfaces, as evidenced by the prolonged relaxation time (τ3) in the VRe-ReS2@ZnO heterostructure. This study offers valuable insights into the rational construction of heterojunctions through tailored interfacial bonding and surface/interface charge transfer pathways. These endeavors facilitate the modulation of electron transfer dynamics, ultimately yielding superior nonlinear optical conversion efficiency and effective charge regulation in optoelectronic functional materials.

Subthreshold Current Suppression in ReS2 Nanosheet-Based Field-Effect Transistors at High Temperatures

Two-dimensional rhenium disulfide (ReS2), a member of the transition-metal dichalcogenide family, has received significant attention due to its potential applications in field-effect transistors (FETs), photodetectors, and memories. In this work, we investigate the suppression of the subthreshold current during the forward voltage gate sweep, leading to an inversion of the hysteresis in the transfer characteristics of ReS2 nanosheet-based FETs from clockwise to anticlockwise. We explore the impact of temperature, sweeping gate voltage, and pressure on this behavior. Notably, the suppression in current within the subthreshold region coincides with a peak in gate current, which increases beyond a specific temperature but remains unaffected by pressure. We attribute both the suppression in drain current and the presence of peak in gate current to the charge/discharge process of gate oxide traps by thermal-assisted tunnelling. The suppression of the subthreshold current at high temperatures not only reduces power consumption but also extends the operational temperature range of ReS2 nanosheet-based FETs.

ReS2 on GaN Photodetector Using H+ Ion-Cut Technology

The wafer-scale single-crystal GaN film was transferred from a commercial bulk GaN wafer onto a Si (100) substrate by combining ion-cut and surface-activated bonding. Well-defined, uniformly thick, and large-scale wafer size ReS₂ multilayers were grown on the GaN substrate. Finally, ReS₂ photodetectors were fabricated on GaN and sapphire substrates, respectively, and their performances were compared. Due to the polarization effect of GaN, the ReS₂/GaN photodetector showed better performance. The ReS₂/GaN photodetector has a responsivity of 40.12 A/W, while ReS₂/sapphire has a responsivity of 0.17 A/W. In addition, the ReS₂/GaN photodetector properties have reached an excellent reasonable level, including a photoconductive gain of 447.30, noise-equivalent power of 1.80 × 10^-14 W/Hz^1/2, and detectivity of 1.21 × 10¹⁰ Jones. This study expands the way to enhance the performance of ReS₂ photodetectors.

Liquid-Phase Exfoliation of Rhenium Disulfide by Solubility Parameter Matching

In this work, we provide a detailed account of the liquid-phase exfoliation (LPE) of rhenium disulfide (ReS₂), a promising new-generation two-dimensional material. By screening LPE in a wide range of solvents, we show that the most optimal solvents are characterized by similar Hildebrand or dispersive Hansen solubility parameters of 25 and 18 MPa^1/2, respectively. Such values are attained by solvents such as N-methyl-2-pyrrolidone, N,N-dimethylformamide, and 1-butanol. In line with solution thermodynamics, we interpret the conditions for high-yield exfoliation as a matching of the solvent and ReS₂ solubility parameters. Using N-methyl-2-pyrrolidone as an exemplary exfoliation solvent, we undertook a detailed analysis of the exfoliated ReS₂. In-depth morphological, structural, and elemental characterization outlined that the LPE procedure presented here produces few-layer, anisotropically stacked, and chemically pure ReS₂ platelets with long-term stability against oxidation. These results underscore the suitability of LPE to batch-produce few-layer and pristine ReS₂ in solvents that have a solubility parameter close to 25 MPa^1/2.

2D Re-Based Transition Metal Chalcogenides: Progress, Challenges, and Opportunities

The rise of 2D transition-metal dichalcogenides (TMDs) materials has enormous implications for the scientific community and beyond. Among TMDs, ReX2 (X = S, Se) has attracted significant interest regarding its unusual 1T' structure and extraordinary properties in various fields during the past 7 years. For instance, ReX2 possesses large bandgaps (ReSe2: 1.3 eV, ReS2: 1.6 eV), distinctive interlayer decoupling, and strong anisotropic properties, which endow more degree of freedom for constructing novel optoelectronic, logic circuit, and sensor devices. Moreover, facile ion intercalation, abundant active sites, together with stable 1T' structure enable them great perspective to fabricate high-performance catalysts and advanced energy storage devices. In this review, the structural features, fundamental physicochemical properties, as well as all existing applications of Re-based TMDs materials are comprehensively introduced. Especially, the emerging synthesis strategies are critically analyzed and pay particular attention is paid to its growth mechanism with probing the assembly process of domain architectures. Finally, current challenges and future opportunities regarding the controlled preparation methods, property, and application exploration of Re-based TMDs are discussed.