Atomically thin semiconductors hold great potential for nanoscale photonic and optoelectronic devices because of their strong light absorption and emission. Despite progress, their application in integrated photonics is hindered particularly by a lack of stable layered semiconductors emitting in the infrared part of the electromagnetic spectrum. Here we show that titanium trisulfide (TiS₃), a layered van der Waals material consisting of quasi-1D chains, emits near infrared light centered around 0.91 eV (1360 nm). Its photoluminescence exhibits linear polarization anisotropy and an emission lifetime of 210 ps. At low temperature, we distinguish two spectral contributions with opposite linear polarizations attributed to excitons and defects. Moreover, the dependence on excitation power and temperature suggests that free and bound excitons dominate the excitonic emission at high and low temperatures, respectively. Our results demonstrate the promising properties of TiS₃ as a stable semiconductor for optoelectronic and nanophotonic devices operating at telecommunication wavelengths.

The control of defect states is becoming a powerful approach to tune two-dimensional materials. Black phosphorus (BP) is a layered material that offers opportunities in infrared optoelectronics. Its band gap depends strongly on the number of layers and covers wavelengths from 720 to 4000 nm from monolayer to bulk, but only in discrete steps and suffering from poor photostability. Here, we demonstrate tunable and stable infrared emission from defect states in few-layer BP. First, we demonstrate a continuous blue shift of the main photoluminescence peak under laser exposure in air due to the creation of crystal defects during photo-oxidation. The tunable emission spectrum continuously bridges the discrete near-infrared energies of few-layer BP for a decreasing number of layers. Second, using plasma-enhanced encapsulation, we report the creation and protection of defects with peak emission energy between bilayer and trilayer BP. The emission is photostable and has an efficiency comparable to that of pristine layers while retaining the strong polarization anisotropy characteristic of BP. Our results put forward defect engineering in few-layer BP as a flexible strategy for stable and widely tunable infrared sources and detectors in integrated spectrometers and hyperspectral sensors.

The chemical reactivity of metals at inappropriate climate conditions can be a threat to metallic cultural heritage. It is known that oxygen plays an important role in the corrosion and decay of metallic objects. Oxide formation is among the most prevalent destructive phenomena in this field. The metallic archaeological objects lose their original shape due to the oxide layer that develops on their surface. Among physical-mechanical and chemical techniques used in the past to remove the oxide layer from these antiques, Cold plasma technology has been proposed as a novel safe method to successfully achieve this goal. In a plasma medium, which can be formed by an electrical discharge, chemically reactive species exhibit a unique behavior in response to the injected gas type, electrical and chemical parameters, etc. This special behavior aids in achieving the user's goal through physicochemical phenomena. In this study, Hydrogen gas, with its reductive character, in the plasma phase provides free radicals of Hydrogen reacting to the copper oxide layer on ancient coins. As a result of this plasma reduction reaction, separation of the oxide layer from the copper surface is achievable. This phenomenon which is called Plasma cleaning, is a type of etching. Plasma cleaning does not destroy surface structure and information contained within metallic heritage artifacts. The feasibility of this non-destructive cleaning method has been investigated for the preservation and restoration of ancient copper coins dating back roughly 300 years ago. These ancient copper coins were exposed to a cold hydrogen plasma for 120 minutes. Results show that Tenorite and Spertiniite formed on the surface of coins have been successfully removed. The black color of Tenorite, a type of copper oxide, gives a dark appearance to copper coins' surface, and Spertitnite, as a copper hydroxide, exhibits a blue-green color on copper coins. According to the results, after 2 hours of hydrogen plasma treatment, not only these green spots have been removed, but also the dark appearance of the entire surface of the coin has been reduced. This amount of clearance is a good result considering the untreated area. Moreover, Figure 1 illustrates the coin's surface using SEM (A) before and (B) after Hydrogen plasma treatment. These images were obtained at a 200x magnification from the surface. In contrast to Figure 1(A), which had heavily polluted surfaces, case B's dark pollution has been removed, reducing the amount of darkness on the coin's surface. This study shows the efficacy of Plasma cleaning for the preservation and restoration of ancient copper coins. Figure 1

Chemical vapor deposition (CVD) is one of the most promising approaches for synthesizing high-quality monolayer transition metal dichalcogenides (TMDs), yet achieving uniform and predictable growth remains challenging. The main difficulty arises from the complex interplay of thermodynamic and kinetic factors, especially the dynamics and spatial distribution of vapor precursors, which strongly influence nucleation and domain evolution. Although various reactor geometries and growth recipes have produced monolayers, these strategies rarely generalize, underscoring the need for a deeper understanding of vapor-phase transport to enable predictive growth. To address this gap, we use computational fluid dynamics (CFD) to model vapor-phase transport during WS₂ CVD growth and reduce the number of parameters that must be optimized experimentally. The model provides a detailed description of sulfur vapor, treating S₂ as the dominant species and calculating key transport properties including heat capacity, viscosity, thermal conductivity, and diffusivity using kinetic-theory relations. Our simulations show how carrier-gas composition, substrate position, and heating profiles shape the local sulfur flux, which governs nucleation density and domain size. By resolving these effects, the CFD model helps narrow the experimental parameter window and reduces dependence on trial-and-error optimization. We also applied an oxygen-plasma substrate pre-treatment and used a solution-based precursor to ensure uniform precursor deposition. WS₂ monolayers were then synthesized under optimized conditions guided by the CFD simulation and characterized using Raman spectroscopy, photoluminescence (PL), SEM, and differential reflection, confirming their high quality and uniformity. Our computational–experimental approach presents a more predictive framework for scalable and reproducible growth of two-dimensional TMD monolayers.

Nanostructured single-phase metal crystals with single and well-defined crystal structures exhibit unique, predictable, and stable properties that are distinct from those of multiphase crystals.