No abstract

Among various available materials used in transparent and flexible devices, MXenes are attracting attention as a brand-new candidate in this category. Ti 3 C 2 Tx 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 ∼424 Ω/sq. and transmittance of ∼87%. The aging stability of MXene-coated PET films against oxidation under ambient conditions was studied up to 28 days and resistance change was found ∼30% during this period. The flexibility test showed low bending resistance change (∼1.5%) at 1000th cycle and cumulative resistance change of ∼20% at a bending radius of ∼3.9 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 ∼80% at 60 V. The flexible smart windows operated normally even at ∼4 mm bending radius.

A vacuum-coupling technique is suggested to fabricate a glass-based PDLC, without using a roll-to-roll process, to improve the optical properties.

Polymer-dispersed liquid crystals (PDLCs), an indispensable class of electrically switchable materials, where nano- or microsized liquid crystal (LC) droplets are phase-separated from the polymer matrix, have been widely used in the fabrication of highly efficient and systematic smart windows. In this paper, we explored the effect of the photoinitiator concentration on the morphology and electro-optical properties of PDLC films based on thiol and acrylates. We prepared PDLC films using various concentrations of the photoinitiator, while keeping the concentrations of LC and monomers constant. We observed that the concentration of the photoinitiator directly influences the phase separation process, which in turn determines the morphology and electro-optical characteristics of the PDLC film. Thus, an optimized amount of the photoinitiator is required to prepare PDLC films with high transmittance and low switching time, haze, and power consumption. The optimized photoinitiator concentration can have a transmittance ΔT (difference between on- and off-state transmittances) of >85% at a low driving voltage.