RESUMEN
Due to its semiconducting nature, controlled growth of large-area chemical vapor deposition (CVD)-grown two-dimensional (2D) molybdenum disulfide (MoS2) has a lot of potential applications in photodetectors, sensors, and optoelectronics. Yet the controllable, large-area, and cost-effective growth of highly crystalline MoS2 remains a challenge. Confined-space CVD is a very promising method for the growth of highly crystalline MoS2 in a controlled manner. Herein, we report the large-scale growth of MoS2 with different morphologies using NaCl as a seeding promoter for confined-space CVD. Changes in the morphologies of MoS2 are reported by variation in the amount of seeding promoter, precursor ratio, and the growth temperature. Furthermore, the properties of the grown MoS2 are analyzed using optical microscopy, scanning electron microscopy (SEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX), and atomic force microscopy (AFM). The electrical properties of the CVD-grown MoS2 show promising performance from fabricated field-effect transistors. This work provides new insight into the growth of large-area MoS2 and opens the way for its various optoelectronic and electronic applications.
RESUMEN
Among various available materials used in transparent and flexible devices, MXenes are attracting attention as a brand-new candidate in this category. Ti3C2Tx MXene as a 2D material has exceptional properties, making it a potential material having numerous applications in different areas. Because of its high conductivity, it can be used in transparent conducting electrodes (TCEs). In this study, the MXenes etched by highly concentrated acid at 50 °C,were spin-coated on polyethylene terephthalate (PET) film and annealed at moderate temperatures up to 170 °C. The adhesion of MXene to PET was found to be remarkably improved by annealing. These TCEs exhibited a sheet resistance of â¼424 Ω/sq. and transmittance of â¼87%. The aging stability of MXene-coated PET films against oxidation under ambient conditions was studied up to 28 days and resistance change was found â¼30% during this period. The flexibility test showed low bending resistance change (â¼1.5%) at 1000th cycle and cumulative resistance change of â¼20% at a bending radius of â¼3.9 mm after 1000 cycles. These transparent, flexible, and conducting electrodes were used to fabricate polymer dispersed liquid crystal (PDLC)-based flexible smart windows. The smart windows fabricated by curing PDLC mixture sandwiched between the MXene electrodes were also found flexible in ON/OFF states. The MXene-based flexible smart windows resulted in good opacity in the OFF state and high transparency in the ON state, exhibiting low threshold voltage <10 V and high transmittance â¼80% at 60 V. The flexible smart windows operated normally even at â¼4 mm bending radius.
RESUMEN
Polymer-dispersed liquid crystals (PDLCs) exhibiting transmittance switching are utilized for preserving energy and protecting privacy. Here we prepared a typical PDLC mixture from a commercially available polymer and liquid crystal with nano-beads. A wire-bar coater was used to coat the PDLC mixture on indium-tin-oxide-coated glass, and a PDLC cell was assembled by coupling another glass in a vacuum, instead of a polymer film. Uniform glass-based PDLCs were fabricated successfully with an area of 15 × 15 cm2, while an injection process with capillary action was not available for this large-scale device fabrication. The switching behavior of the cells was characterized by ramping the AC voltage, and a transmittance change of â¼70% was measured. In a typical roll-to-roll process, only flexible polymer films have been used in lamination, in which deterioration in transparency occurs over the course of time, reducing the efficiency. In this study, to improve the optical properties, PDLC switchable glazing is fabricated directly onto glass substrates instead of onto plastic polymers. This PDLC switchable glazing, exhibiting low haziness and wide-angle vision, can be fabricated at a large scale by a vacuum-coupling process, with potential use as glass windows for energy-efficient buildings.