Two-dimensional (2D) layered black phosphorus (BP), with a direct band gap and high carrier mobility, has shown great potential for next generation electronics and optoelectronics. However, how to prepare a large-area 2D material film is still a big problem for realizing its practical applications. Herein, an improved one-step solution-processable method is put forward to solving this problem to get uniform and large-area BP film. Our results show that the designed electrodes can be fully covered by BP flakes and the corresponding FET reveals relatively high performance. Our study opens a new avenue in fabricating large-area ultra-thin BP films.
We have developed a method for designing polymer and graphene nanoplatelet (GNP) composites that show high dielectric constants over a wide range of GNP contents. GNPs are dispersed in the composites through plasma-surface modification and aligned by applying an electric field (EF). This creates a large number of microcapacitor structures of GNPs separated by the polymer. The maximum dielectric constant of the sample to which the EF is applied is approximately twice that of the sample to which the EF is not applied. Furthermore, the maximum dielectric constants of the samples with plasma-surface modified GNPs are higher than those of the samples with unmodified GNPs. The composites show high dielectric constants (∼500 at 100 Hz) over a wide range of GNP contents (6 ∼ 10 wt%) while maintaining mechanical flexibility (Young’s modulus:12 ± 4 MPa).
The two-dimensional bi-layer MoS2 is less investigated as compared to monolayer and few-layer (4–6 layers) MoS2 for fundamental aspects and applications such as photodetectors, transistors, etc. In the present work, we prepare triangular-shaped bi-layer MoS2 over SiO2/Si substrate via chemical vapour deposition (CVD) technique for surface enhanced Raman scattering (SERS) based detection of Rhodamine 6G (R6G). We perform density functional theory calculations and spectroscopy studies to investigate the semiconducting feature of bi-layer MoS2. We demonstrate the nanomolar concentration (10-9 M) limit for R6G detection at room temperature using pristine bi-layer MoS2 as SERS substrate. Further, we also examine the cryogenic response of the SERS detection of R6G with bi-layer MoS2 for the first time. The high detection limit of CVD-grown bi-layer MoS2 is ascribed to the charge transfer enabled via vibronic coupling between MoS2 and R6G molecules. This study paves the way for cryogenic-based SERS sensing.