Recent advances in 2D transition metal dichalcogenide-based photodetectors: a review.

Two-dimensional (2D) transition metal dichalcogenides (TMDs) have emerged as a highly promising platform for the development of photodetectors (PDs) owing to their remarkable electronic and optoelectronic properties. Highly effective PDs can be obtained by making use of the exceptional properties of 2D materials, such as their high transparency, large charge carrier mobility, and tunable electronic structure. The photodetection mechanism in 2D TMD-based PDs is thoroughly discussed in this article, with special attention paid to the key characteristics that set them apart from PDs based on other integrated materials. This review examines how single TMDs, TMD-TMD heterostructures, TMD-graphene (Gr) hybrids, TMD-MXene composites, TMD-perovskite heterostructures, and TMD-quantum dot (QD) configurations show advanced photodetection. Additionally, a thorough analysis of the recent developments in 2D TMD-based PDs, highlighting their exceptional performance capabilities, including ultrafast photo response, ultrabroad detectivity, and ultrahigh photoresponsivity, attained through cutting-edge methods is provided. The article conclusion highlights the potential for ground-breaking discoveries in this fast developing field of research by outlining the challenges faced in the field of PDs today and providing an outlook on the prospects of 2D TMD-based PDs in the future.

The green synthesis of magnesium oxide nanocomposite-based solid phase for the extraction of arsenic, cadmium, and lead from drinking water.

Solid-phase extraction (SPE) has attracted the attention of scientists because it can increase the selectivity and sensitivity measurements of analytes. Therefore, this study is designed to synthesise magnesium oxide nanoparticles (D-MgO-NPs) by an eco-friendly method using biogenic sources Duranta erecta followed by fabricating its chitosan-based polymeric composite (D-MgO-NC) for the SPE of heavy metals (HMs), i.e., arsenic (As), cadmium (Cd), and lead (Pb) from drinking water. Various analytical techniques were used for the surface characterization of D-MgO-NPs and D-MgO-NC. FTIR findings confirmed the formation of D-MgO-NC based on MgO association with the -OH/-NH2 of the chitosan. D-MgO-NC showed the smallest size of particles with rough surface morphology, followed by the crystalline cubic structure of MgO in its nanoparticle and composites. The synthesised D-MgO-NC was used as an adsorbent for the SPE of HMs from contaminated water, followed by their detection by atomic absorption spectrometry. Various experimental parameters, including pH, flow rate, the concentration of HMs, eluent composition, and volume, were optimised for the preconcentration of HMs. The limits of detection for As, Cd, and Pb of the proposed D-MgO-NC-based SPE method were found to be 0.008, 0.006, and 0.012 µm L-1, respectively. The proposed method has an enrichment factor and relative standard deviation of >200 and <5.0%, respectively. The synthesised D-MgO-NC-based SPE method was successfully applied for the quantitative detection of As, Cd, and Pb in groundwater samples, which were found in the range of 18.3 to 15.2, 3.20 to 2.49, and 8.20 to 6.40 µg L-1, respectively.

The effect of substitutional doping of Yb2+on structural, electronic, and optical properties of CsCaX3(X: Cl, Br, I) phosphors: a first-principles study.

Using first-principles calculations, the effects of Yb2+substitutional doping on structural, electronic, and optical properties of a series of perovskite compounds CsCaX3(X: Cl, Br, I), have been investigated. We employed generalized gradient approximation (GGA) and HSE hybrid functional to study the electronic and optical properties. A series of pristine CsCaX3(X: Cl, Br, I) is characterized as a non-magnetic insulator with indirect bandgap perovskite materials. These phosphor materials are suitable candidates for doping with lanthanide series elements to tune their electronic bandgaps according to our requirements because of their wide bandgaps. The calculated electronic bandgaps of CsCaX3(X: Cl, Br, I) are 3.7 eV (GGA) and 4.5 eV (HSE) for CsCaI3, 4.5 eV (GGA) and 5.3 eV (HSE) for CsCaBr3, and 5.4 eV (GGA) and 6.4 eV (HSE) for CsCaCl3. According to formation energies, the Yb2+doped at the Ca-site is thermodynamically more stable as compared to all possible atomic sites. The electronic band structures show that the Yb2+doping induces defective states within the bandgaps of pristine CsCaX3(X: Cl, Br, I). As a result, the Yb2+doped CsCaX3(X: Cl, Br, I) become the direct bandgap semiconductors. The defective states above the valence band maximum are produced due to thef-orbital of the Yb atom. The impurity states near the conduction band minimum are induced due to the major contribution ofd-orbital of the Yb atom and the minor contribution ofs-orbital of the Cs atom. The real and imaginary parts of the dielectric function, optical reflectivity, electron energy loss spectrum, extinction coefficient, and refractive index of pristine and Yb2+doped CsCaX3(X: Cl, Br, I) were studied. The optical dispersion results of dielectric susceptibility closely match their relevant electronic structure and align with previously reported theoretical and experimental data. We conclude that the Yb2+doped CsCaX3(X: Cl, Br, I) are appealing candidates for optoelectronic devices.