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Expressing melancholy and emotional yearning of the past time, called Nostalgia is cause of people movement from homeland to other city, state, country or region, seeking for employment, education, political asylum, citizenship or persuading security in safer and less crimes places or safeguard from environmental disaster etc. is called migration which, since long, has resulted in manifold complications. As an immigrant, despite of forcedly bifurcating from his homeland for one reason or the other, he can never eradicate his past memories and deep attachments with motherland. Soon after the division of subcontinent, people of the area also left their origin to settle down in new country for safety and security but during crossing the durned line, brutal violence and pitiless massacres on both sides caused enormous killing of family members and abduction of young girls and women.

Early diagnosis of dental caries progression can prevent invasive treatment and enable preventive treatment. In this regard, dental radiography is a widely used tool to capture dental visuals that are used for the detection and diagnosis of caries. Different deep learning (DL) techniques have been used to automatically analyse dental images for caries detection. However, most of these techniques require large-scale annotated data to train DL models. On the other hand, in clinical settings, such medical images are scarcely available and annotations are costly and time-consuming. To this end, we present an efficient self-training-based method for caries detection and segmentation that leverages a small set of labelled images for training the teacher model and a large collection of unlabelled images for training the student model. We also propose to use centroid cropped images of the caries region and different augmentation techniques for the training of self-supervised models that provide computational and performance gains as compared to fully supervised learning and standard self-supervised learning methods. We present a fully labelled dental radiographic dataset of 141 images that are used for the evaluation of baseline and proposed models. Our proposed self-supervised learning strategy has provided performance improvement of approximately 6% and 3% in terms of average pixel accuracy and mean intersection over union, respectively as compared to standard self-supervised learning. Data and code will be made available to facilitate future research. 2023, The Author(s). This work is supported in parts by EPSRC grant no: EP/T021063/1 and Ajman University Internal Research Grants No. [2021-IRGDEN-7 and RTG-2022-DEN-01]. The research findings presented in this article are solely the author(s) responsibility. Scopus

The transition metal sulfides have gained extensive interest in energy storage devices owing to their unique features. However, the research-based on cobalt, copper and manganese sulfide composites is limited while they are considered as promising contenders for supercapacitor electrodes. The simplest and facile one-step electrodeposition technique was adopted for the direct growth of CuMnS and CoMnS on a Ni-substrate. The electrochemical properties of CuMnS and CoMnS electrodes were investigated and maximum specific capacitances of 1691 and 2290 F/g, respectively, were obtained at 10 A/g current density. Further, these electrodes are investigated with activated carbon (AC) electrode to fabricate asymmetric supercapacitor devices where CoMnS//AC exhibited superior energy density values than CuMnS//AC device. However, both the devices show a relatively uniform capacitance retention rate (~94%) after 2500 charging-discharging cycles. Furthermore, the role of capacitive- and diffusive-controlled contributions in the charge storage phenomenon of supercapacitor devices are explicitly scrutinized by employing Dunn's model. Co-electrodeposition of transition metal sulfides has great potential as electrode material for highly effective supercapacitor devices.

Supercapattery, a hybrid energy storage device, gained remarkable attention due to its extraordinary energy storage performance. These devices constitute much better power and energy densities than supercapacitors and batteries. Here, we have investigated strontium phosphide and polyaniline (PANI) composites for supercapattery devices. The strontium phosphide was synthesized via facile sono-chemical method whereas the polyaniline was obtained through polymerization of aniline in acidic environment. Electrochemical performance of different mass ratios of strontium phosphide and polyaniline that are 75/25% and 50/50% were tested in three electrode assembly. Electrochemical characterization including galvanostatic charge discharge (GCD), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) were performed to probe the electroactive nature of the composites. The initial characterization predicts the battery grade nature of synthesized composites which were confirmed through theoretical approach. The sample S3 indicates highest specific capacity of 192 Cg-1 in CV at a scan rate of 10 mV/s and 196 C/g in GCD at a current density of 0.4 A/g. In light of electrochemical performance, the 50/50% composite electrode was further investigated for supercapattery by sandwiching it with activated carbon electrode (capacitive electrode). The supercapattery (AC//S3) operates reliably at 0–1.7 V wider potential window in 1 M KOH environment and showing excellent specific capacity of 122.5 C/g at 0.6 A/g while demonstrating better rate capability of 37% at 3.0 A/g. Besides, this device expresses an outstanding performance in terms of energy and power density, 28.9 Wh/kg of maximum specific energy is achieved in line with 1020 W/kg of power density at 0.4 A/g. This device reveals an excellent power density of 5100 W/kg at the cost of 10.95 Wh/kg energy density. In last the device durability was examined by subjecting it to 2000 consecutive charge discharge cycles. Strontium phosphide/PANI composites would be novel electrode materials for state of the art supercapattery devices.

Hydrogen as a vehicular fuel has attracted extensive attention. However, the challenge of its storage extremely confined its applications. Current researchers are mostly focused on the development of porous nanomaterials having large specific surface areas for improving the gravimetric densities, which undoubtedly restrain the volumetric densities of hydrogen storage. Here, hexagonal GaN micro–sheets are reported for hydrogen storage. Compared with the porous nanostructures, the highly crystalline structure micro–sheets ensure the volumetric density of GaN. The adsorption and the insertion of the hydrogen atoms into the crystal lattice and Ga vacancies result in reversible gravimetric densities. GaN micro–sheets absorption results are comparable to porous nanomaterials and higher than many oxide and nitride materials. Furthermore, the role of Ga vacancies has been correlated with morphology and the absorption mechanism.

Electrical conductivity and optical transmittance of nickel nanowire (Ni-NW) networks are reported in this work. The Ni-NWs were irradiated with 3.5, 3.8 and 4.11[Formula: see text]MeV proton (H[Formula: see text]) ions at room temperature. The electrical conductivity of Ni-NW networks was observed to increase with the increase in beam energies of H[Formula: see text] ions. With the increase in ions beam energies, electrical conductivity increases and this may be attributed to a reduction in the wire–wire point contact resistance due to the irradiation-induced welding of NWs. Welding is probably initiated due to H[Formula: see text] ion-irradiation induced heating effect that also improved the crystalline quality of the NWs. After ion beam irradiation, localized heat is generated in the NWs due to ionization which was also verified by SRIM simulation. Optical transmittance is increased with increase in the energy of H[Formula: see text] ions. The Ni-NW networks subjected to an ion beam irradiation to observe corresponding changes in electrical conductivity and optical transparencies are promising for various nanotechnological applications, such as highly transparent and conducting electrodes.

This paper presents a platform tolerant ultra-high radio frequency identification (UHF RFID) tag design for hard to tag supply chain items such as large metal and wooden containers. The proposed design consists is backed by multi-resonant surface carefully designed using characteristics mode analysis. As a result, this tag design features a long read range and covers most of UHF RFID frequency bands. The evaluation of the read range associated with fabricated prototype of proposed tag configuration is done through turn on power measurements using Tagformance Pro setup. A variety of subjects with different physical constitutions such as metal, wood and glass are considered in order to demonstrate the robustness of our solution. The proposed tag offers a relatively longer reader range of 12.5 m after mounting on piece of metal, wood and glass materials. Therefore, this tag design is suitable candidate for supply chain visibility and cargo monitoring.

We performed ab initio calculations to study the structural and optoelectronic properties of simple and slab phase TaNO using density functional theory (DFT), in which the full potential augmented plane wave (FP-LAPW) method was implemented using the computational code Wien 2k. The modified Becke-Johnson potential (mBJ-GGA) was used for these calculations. The calculated band structure and electronic properties revealed an indirect bandgap for simple TaNO (3.2 eV) and a direct bandgap for slab TaNO (1.5 eV). The interband electronic transitions were investigated from the band structure, and transition peaks were observed from the imaginary part of the dielectric function. These transitions are due to Ta-p, N-p and O-p orbitals for simple TaNO and Ta-p, N-s as well as O-p orbitals for slab TaNO. The plasmon energy was related to the main peak of the energy loss function, which was approximately 10 eV. The static value of the dielectric constant and the refraction were close to the experimental values. In general, slab TaNO shows different properties and is more suitable for optoelectronic applications due to direct bandgap.

In this study, high-quality single crystalline Mn-doped CdS nanosheets were synthesized by the chemical vapor deposition method and their photoluminescence (PL) properties were determined. Energy dispersive X-ray analysis, the non-uniform peak shifts in the Raman spectra, and micro-PL mapping demonstrated the presence of Mn ions in the nanosheets. The temperature-dependent (78–400 K) micro-PL spectra showed that the multi-peak emissions ranged from 455.302 to 749.901 nm. The band-edge emission exhibited a pronounced red shift (∼8 nm) as the temperature increased from 78 to 400 K due to the formation of exciton magnetic polarons (EMPs). The orange emission (597.621 nm) was due to the 4T1(4G) → 6A1(6S) d–d transition between the excited state and ground state of Mn2+. The shorter lifetimes compared with the forbidden d-d transition and deep traps due to structural relaxation confirmed that the red (670.832 nm) and near-infrared (749.901 nm) emissions were associated with localized EMPs. The PL emission centered at 471.780 nm appeared at 80 K due to free-exciton C (FXC). Emissions centered at 455.302 and 463.501 nm were detected for the first time in our samples. Interestingly, both of these emissions appeared on the higher energy side of FXC and unlike EMP, they did not follow the Varshni function. Therefore, we assigned these emissions to bound magnetic polarons. These novel emissions in dilute magnetic semiconductors could be beneficial for further applications in photovoltaics, full-color displays, and nanoscale devices.

Schottky-barrier diodes have great importance in power management and mobile communication because of their informal device technology, fast response and small capacitance. In this research, a p-type molybdenum ditelluride (p-MoTe2) based Schottky barrier diode was fabricated using asymmetric metal contacts. The MoTe2 nano-flakes were mechanically exfoliated using adhesive tape and with the help of dry transfer techniques, the flakes were transferred onto silicon/silicon dioxide (Si/SiO2) substrates to form the device. The Schottky-barrier was formed as a result of using ultra-low palladium/gold (Pd/Au) and high resistive chromium/gold (Cr/Au) metal electrodes. The Schottky diode exhibited a clear rectifying behavior with an on/off ratio of ∼103 and an ideality factor of ∼1.4 at zero gate voltage. In order to check the photovoltaic response, a green laser light was illuminated, which resulted in a responsivity of ∼3.8 × 103 A W−1. These values are higher than the previously reported results that were obtained using conventional semiconducting materials. Furthermore, the barrier heights for Pd and Cr with a MoTe2 junction were calculated to be 90 meV and 300 meV, respectively. In addition, the device was used for rectification purposes revealing a stable rectifying behavior.

An axially symmetric rotating Banados-Teitelboim-Zanelli (BTZ) black hole is considered for comprehending its interior information. The largest space-like hyper-surface is chosen to estimate its maximal interior volume as a time-dependent quantity. Similarly, the quantum mode entropy of the scalar field associated with this volume is found to increase with Eddington time. An evolution relation between the variation of quantum mode entropy and Bekenstein-Hawking entropy is obtained for an infinitesimal time interval. On comparing to higher-dimensional black holes, the characteristic feature of this evolution relation is its divergent character.

A number of ternary-semiconductor oxides have shown promise for potential applications in catalysis, thermoelectricity, optoelectronics and electrochemistry. In this work, the thermoelectric and optoelectronic properties of $$\hbox {La}_{2}\hbox {Pd}_{2}\hbox {O}_{5}$$ compound are studied by the full-potential linearized augmented plane wave method based on density functional theory. The electronic band structure shows an indirect band gap of 1.342 eV for $$\hbox {La}_{2}\hbox {Pd}_{2}\hbox {O}_{5}$$ . Partial and total density of states indicate strong hybridization among different electronic orbitals. The upper part of the valence band is dominated by the Pd-d and O-p states, while the lower conduction band originates mainly from the Pd-d state. Dielectric functions including the imaginary and real parts, along with other optical constants, such as absorption coefficient, energy loss function, reflectivity and refractive index, have been reported for the first time. Thermoelectric properties, including electrical and thermal conductivity, Seebeck coefficient and power factor with variation in temperature are also presented and discussed using semi-classical Boltzmann transport theory for the first time for $$\hbox {La}_{2}\hbox {Pd}_{2}\hbox {O}_{5}$$ . It has been found that $$\hbox {La}_{2}\hbox {Pd}_{2}\hbox {O}_{5}$$ has attractive optoelectronic and thermal properties that can make it a suitable candidate for efficient thermoelectric and optoelectronic device applications.

Oxynitrid perovskitu je velmi zajímavý díky jejich použití jako foto-katalyzátorů. Zkoumali jsme elektronické, termoelektrické a optické vlastnosti ATaO2N (A = Ba, Sr, Ra) s generalizovaným gradientem plus Hubbardovou aproximací (GGA + U). V elektronických vlastnostech jsme pro každou sloučeninu vypočítali hustotu stavů (celkem a parciálních), strukturu pásma, abychom mohli extrahovat jejich mezery v pásmu, povahu a pravděpodobnost přechodu, když se změní kation. Optické vlastnosti byly prozkoumány výpočtem dielektrické konstanty e(ω), indexu lomu n(ω), odrazivosti R(ω), optické ztráty L (ω), a absorpční koeficienty I(ω), odezvy na různé fotonové energie. Abychom prozkoumali možnost použití těchto sloučenin v termoelektrických zařízeních, vypočítali jsme jejich transportní vlastnosti z Boltzmanovy transportní teorie. Zkoumali jsme jejich tepelnou vodivost κ, elektrickou vodivost σ, seebeckův koeficient S, účiník PF a bezrozměrný údaj o hodnotě ZT. Perovskite oxynitride are of great interest due to their use as photo-catalysts. We investigated the electronic,thermoelectric and optical properties of ATaO2N (A= Ba, Sr, Ra) with generalized gradient plus Hubbard approximation (GGA+U). In electronic properties, we have computed, for each compound, densities of states (total and partial), band structure to extract their band gaps, nature and transition probability when the cation changes. Optical properties were explored by calculating dielectric constant ε (ω), refractive index n (ω), reflectivity R (ω), optical loss L (ω), and absorption coefficient I (ω) response against different photon energies. In order to examine the possibility of using these compounds in thermoelectric devices, we calculated their transport properties from Boltzman transport theory. We examined their thermal conductivity κ, electrical conductivity σ, seebeck coefficient S, power factor PF and dimensionless figure of merit ZT.

Low-temperature synthesis of ZnTe nanowires (NWs) is a helpful advancement in realization of low cost nanostructured electronic devices. This article reports a novel and low temperature (275 °C) synthesis of one-dimensional (1D) NWs of ZnTe on glass substrate. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive x-ray analysis (EDX) revealed that prepared NWs have good crystallinity and yield. Optical properties, reported in this article as UV spectroscopy and photoluminescence (PL), confirm its energy gap of 2.24 eV. Keywords: ZnTe, Synthesis, Low-temperature, Optical properties

The incorporation of 3d magnetic ions into intrinsic semiconductors is one of the sophisticated way to tune their opto-magnetic behavior but dire need is to determine the functional changes resulting from doped-ions. Here, dysprosium (Dy) ions have been doped into CdS nanostructures via co-precipitation technique and studied their influence in optical and magnetic properties. The PL of doped-nanostructures exhibited violet, blue (454.5 nm) and orange emissions, simultaneously. The violet emissions correspond to the band edge (BE) emission of CdS and blue emissions appeared due to the f-f transition from Dy4+ to Dy3+ and Dy3+. Burstein-Moss-Effect explains the increased band-gap observed in the doped samples. VSM studies show the formation of ferromagnetism in a diamagnetic CdS nanostructure due to the successful incorporation of Dy3+ ions into CdS which can play a significant role in tuning their optical and magnetic properties for potential applications in optical devices and spintronics.

Self-assembled metal-semiconductor nanostructures for the fabrication of integrated circuitry nanodevices are currently actively pursuited. One prominent example is the one-dimensional semiconductor (CdS) nanobelt on metallic (Cd) heterojunction. In this work, we have synthesized hexagonal Cd micro-rods, Cd micro-spheres and Cd-CdS micro/nano hetrostructures using a simple chemical vapor deposition (CVD) method. In addition to the optimization of synthesis parameters for these micro/nanostructures, we explored the effect of the inclination angle between the substrate and the furnace on the morphologies of these products. Using a range of characterization tools including scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDXS), X-ray photoelectron spectroscopy (XPS), we characterized these micro/nanostructures and found them to be of high quality crystals. Moreover, we performed photoluminescence and lifetime decay studies to confirm that heterostructures are composed of metal-semiconductor heterojunction. These micro/nano-heterostructures are anticipated to be used in photocatalysis and photoelectronic devices.

Improvement of the optical and electrical characteristics is essential to get advanced performance from one dimensional (1D) material. Here, we report the first synthesis of a single crystalline Te-doped CdS nanowires (NWs) by a chemical-vapor-deposition (CVD) method. Room temperature photoluminescence (PL) spectra showed that Te concentration plays an important role in tuning emission color from orange to infrared (IR). Decrease in bandgap and PL intensity with increase in Te concentration was observed as compared to undoped CdS NWs. Red and IR emissions were found at 736.5 and 881 nm for doping concentration >6.06%. To our best knowledge, IR emission band has been observed for the first time in CdS NWs. Red-shift of LO phonon mode and its overtone in Raman spectra, and lifetime of red and IR emissions are longer than bandgap of host indicating the doping effect of CdS NWs. Energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) of the Te-doped CdS NWs further confirms the presence of Te in the CdS NWs. Output characteristics confirm enhanced output current I ds with the increase in doping concentration. A possible growth mechanism was proposed. Doping technique offers to develop high-quality, a very stable, effective, and easily-applicable way to enhance the performance of one dimensional optoelectronic devices and solar cell applications.

Tunable emission from the visible to infrared region in II–VI semiconductor nanostructures makes them ideal candidates for the development of optoelectronic devices. In this study, Zn1−xMnxS (x = 0.01–0.15%) nanobelts (NBs) were prepared via the chemical vapor deposition (CVD) method. The as-grown NBs were investigated by XRD and electron paramagnetic resonance (EPR). A significant lower angle shift was observed in the XRD spectra, which indicated the incorporation of Mn ions. A hyperfine interaction constant A of 68.6 G obtained from the EPR spectra confirmed that Mn2+ ions were successfully incorporated into the ZnS matrix. For higher Mn concentrations, the broadening of the EPR profile was attributed to the aggregation of Mn2+ ions. Moreover, successful Mn-ion doping in individual ZnS NBs was itentified by SEM–EDS and Raman scattering analysis. Raman spectroscopy studies revealed a red-shift at the LO phonons, confirming the presence of Mn ions in ZnS NBs. Room-temperature photoluminescence (PL) showed that the Mn concentration plays an important role in tuning the emission from 452 nm to 877.6 nm (blue to near-infrared:NIR); whereby, up to 15% Mn, PL showed emissions are centered at 447, 535, 580.7, 651.1, and 877.6 nm. Herein, the first two peaks were assigned to anti-ferromagnetic coupling of 4 Mn ions, and the interaction of 2 Mn ions with stack faults in ZnS NBs. The next peak was from the typical d–d transition (4T1(4G) → 6A1(6S)) of Mn2+, and the last two peaks were assigned to the aggregate made up of 2 Mn ions and (MnS)5 cluster-related emission with ferromagnetic coupling. NIR emission was also detected from the 10% Mn-doped CdS NBs. To the best of our knowledge, herein, NIR emission was observed for the first time in ZnS nanostructures. These kinds of nanomaterials may have potential applications in photovoltaics, telecommunications, and remote sensing.

Density functional theoretical (DFT) calculations were carried out to explore the electronic and optical properties of double ordered Ba2NaReO6, Ba2LiReO6, and Sr2LiReO6 perovskites by employing the state-of-the-art exchange-correlation potential, i.e., Tran-Blaha modified Becke-Johnson for the electronic system. The calculated electronic band structures show an indirect band gap along with a semiconductor nature. Total and partial densities of state peaks were analyzed in light of effective contributions of various electronic states. The significant optical parameters, including the components of dielectric constant, the energy loss function, the absorption coefficient, the reflectivity spectra, the refractive index, and the extinction coefficient, were computed and discussed in details for radiation up to 14 eV. Finally, we studied the inter-band contributions from the optical characteristics. Our present study might be considered as first theoretical quantitative calculations of the optical and electronic behavior in the cubic phase of double perovskite materials based on rhenium.

Tunable single-mode lasers are attractive for their potential applications in signal processing, optical communication, and displays. Here we present the Mn(II) ions assisted single-mode lasing occurring at near-infrared (NIR) band instead of the green emission band of CdS nanobelts (NBs) for the first time. Successful substation of Mn(II) ions at the tetrahedral Cd2+ cites in the CdS matrix were confirmed by EPR. Light Mn(II) doping (≤1%) in CdS belts not only red-shifted the Raman modes but also increased crystallinity compared to pure CdS NBs due to strong excitons-phonon couplings. Up to 3 µJ · cm-2 pumping fluence of ns laser, lightly doped CdS:Mn NBs show two photoluminescence (PL) emissions. First emission centered at 514.2 nm (green) corresponds to band-edge of CdS and an in-gap emission centered at 771.4 nm (NIR) corresponds to Mn(II) ions aggregates. After using intense excitation pulse, these NBs exhibited lasing at 791.4 nm with the lowest laser thresholds at 4.2 µJ · cm-2 in the CdS system. This lasing action is further confirmed by lifetime kinetics. The results indicated that the lasing in these NBs involves the localised excitons magnetic polarons and Farby-Perot (F-P) optical resonant processes at room temperature.

Have one ever seen a semiconductor that can issue two-color lasing lines? The diluted magnetic semiconductor (DMS) can do this. Here, we have observed dual lasing lines of 530 nm and 789 nm from a DMS structure of CdS:NiI, in which the excitonic magnetic polaron (EMP) and localized excitonic magnetic polaron (LEMP) are excitations out of ferromagnetic (NiS) x nanocluster and NiI 2 nanoclusters within CdS lattice; both of them could lead to the collective EMP state at high excitation and therein produce coherent emission lines simultaneously. This occurrence is due to the superposition of EMP near CdS bandedge and the combination of the charge-transfer band of (NiI) n cluster with the LEMP within CdS lattice by overcoming the strong electron correlation of NiI cluster in a DMS structure, evidenced also by ab initio calculation. This finding opens a way to understand the collective behaviour of spin-coupled excitons in DMS and to find novel applications in the spin-related quantum technology.

Exciton magnetic polarons (EMPs) are self-organized magnetic quasiparticles that can be formed by excitons in diluted magnetic semiconductors (DMSs). The optical response of EMPs in DMS microstructures is not yet well understood because it is affected by many competing factors, including spin-dependent exchange interactions, phonon coupling, and collective and nonlinear effects upon the dopant concentration and structural relaxation. Here, we report on lasing from collective EMP states in Co(II)-doped CdS nanowires (NWs) and nanobelts (NBs) that we interpret in terms of bosonic lasing, the spontaneous emission of radiation by a single quantum state macroscopically populated by bosonic quasiparticles. The lasing threshold coincides with the appearance of ferromagnetic domains, indicating an important role of spin ordering in the formation of coherent collective EMPs. These results pave the way to the realization of a new type of bosonic laser, different from exciton-polariton lasers, where formation of the...

In this paper, we report the synthesis and optical properties of Fe(III) doped CdS nanobelts (NBs) via simple Chemical Vapor Deposition (CVD) technique to explore their potential in nano-optics. The energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) analysis manifested the presence of Fe(III) ions in the NBs subsequently confirmed by the peak shifting to lower phonon energies as recorded by Raman spectra and shorter lifetime in ns. Photoluminescence (PL) spectrum investigations of the single Fe(III)-doped CdS NBs depicted an additional PL peak centered at 573 nm (orange emission) in addition to the bandedge(BE) emission. The redshift and decrease in the BE intensity of the PL peaks, as compared to the bulk CdS, confirmed the quenching of spectra upon Fe doping. The synthesis and orange emission for Fe-doped CdS NBs have been observed for the first time and point out their potential in nanoscale devices.

Here, we demonstrate a doping technique which remarkably improves the electrical and photoelectric characteristics of a WS2 field effect transistor (FET) by chemical doping. The shift of the threshold voltage towards a negative gate voltage and the red shift of the E12g and A1g peaks in the Raman spectra confirm the n-type doping effect in WS2 FETs. WS2 films show an unprecedented high mobility of 255 cm2 V−1 s−1 at room temperature. The on/off ratio of the output current is ∼108 at room temperature. The mobility of a multilayer ML-WS2 FET was found to be 425 cm2 V−1 s−1 at 5 K. Semiconductor-to-metal transitions were also observed at Vbg > 30 V. A decrease in contact and sheet resistance was observed after potassium iodide (KI) doping. The photocurrent in WS2 FETs was also enhanced after n-type doping. Chemical doping exhibited a very stable, effective, and easy-to-apply method to enhance the performance of a WS2 FET.

We have reported on theoretical insights of LuZnCuAs2 compound from Zintl family using computational code WIEN2k where we optimized unit cell volume at ground state and investigated its structural, electronic, optoelectronic and thermal properties on three different potentials including local density approximation (LDA), generalized gradient approximation (GGA) and generalized gradient approximation plus Tran-Blaha modified Becke-Johnson (GGA + mBJ). The former two suggested a semi-metallic behavior whereas GGA + mBJ showed semiconductor regime with band gap of 0.4 eV. We observed major contribution of 5d-shell of Lutetium (Lu) in density of states (DOS) relative to 3d-shells of Zinc (Zn) and Copper (Cu). We have reported on reflectivity, refractive index, energy loss and absorption of LuZnCuAs2. We also studied thermal behavior of LuZnCuAs2 using BoltzTrap as implemented in WIEN2k code where we calculated its electrical conductivity, Seebeck coefficient, thermal conductivity and the dimensionless figure of merit (ZT).

Spin controlled diluted magnetic semiconductors (DMSs) could bring revolution in the processing speed as well as in enhancing the storage capacity. To achieve its industrial application, several impurities have been doped from the 3d/4f into semiconductors, however, Cr has not yet been doped into CdS 1D nanostructures. Here, in the present study, we report on the Cr-doped CdS 1D nanoneedles synthesized by CVD and studied its optical and magnetic properties. The successful incorporation of Cr-ions into CdS confirmed by EDX and XRD. Along with the increase in Cr-ions concentration, first PL-peak shifted from 514.1 to 558.3 nm associated with the formation of excitonic magnetic polarons (EMPs) and the second peak centered at 993.8 nm may correspond to the aggregation of Cr-ions. For the first time, we tuned CdS emission up to ~ 482 nm covering visible spectral region up to near-infrared (NIR) region. With increasing the Cr-ions concentration up to 6.2%, saturation magnetization (Ms) was significantly enhanced from 0.614 × 10−3 Am2/kg to 0.987 × 10−3 Am2/kg. These findings will promote their future applications in the optoelectronic and spintronic devices.

Achieving tunable emission in semiconductors over a wide-spectral range has always remained a challenge for its potential applications. For this purpose, transition metals (TMs) have been widely doped into II-VI semiconductors, however, least efforts have been made on adding non-metals. Here, we co-doped non-metal and TM, i.e. iodine + nickel (I + Ni) into CdS 1D nanostructures and explored optical properties for the first time. FESEM shows that among CdS: (F + Ni, Cl + Ni, Br + Ni, I + Ni), I + Ni-doped CdS nanobelts (NBs) were thinner and have high crystallinity confirmed by XRD and Raman spectroscopy. Successful incorporation of iodine into CdS NBs was confirmed by EDX. Low temperature (80 K) photoluminescence (PL) of I + Ni doped CdS shows multiple emission centred at 525, 583, 758, and 916 nm, respectively. The first emission corresponds to exciton magnetic polaron (EMP) and the next two emissions correspond to d-d transition (3A2g → 1Eg) and (3T1P → 3T1F) of Ni ions, respectively. The last emission (916 nm) originated only in the I + Ni co-doped CdS NB which may correspond to the iodine incorporated into belts. According to the best knowledge, iodine related emission was detected for the first time. This work will promote their future applications in solar cells and optoelectronic devices.

There is a considerable research interest in enhancing the charge carrier mobility of polymer-based organic field effect transistors (OFETs) through processing techniques. Herein, we investigate the effect of post-deposition annealing temperature on morphology and mobility of solution processible polymer Poly[2,5-(2-octyldodecyl)-3,6-diketopyrrolopyrrole-alt-5,5-(2,5-di(thien-2-yl)thieno [3,2-b]thiophene)], (DPPDTT) based OFETs. The resulting change in the grain size is proportional to the mobility data. At temperatures higher than 100 °C, grain size decreased with obvious desorption due to low Van der Waals forces in the polymer. Our results will hence contribute towards understanding the annealing mechanism in polymers to optimize the performance of DPPDTT based devices.

Two-dimensional (2D) semiconducting TMDCs materials have recently gained much attention and are considered as promising materials with a high surface-to-volume ratio for electronics. The performance of devices greatly affected by environmental factors. For attaining the high performance of the device, environmental issues must be addressed. Here, we have demonstrated an n-type doping effect from DUV + N2 treatment to overcome the environmental influences and to enhance the performance of MoTe2 FET. After the n-type doping effect from DUV + N2 treatment mobility, charge carrier density, and ION/IOFF ratio increased up to 62.4 cm2/Vs, 3 × 1012 cm−2 and 107 respectively. The negative shift of threshold voltage (Vth) and Raman peaks towards the lower wavenumber confirms the n-type doping effect in the MoTe2 FET from DUV + N2 treatment. By using this method, we can change and control the polarity of the MoTe2 FET by changing the doping time. First-principles calculation on the study of structural, electronic and optical properties have been performed using the density functional theory (DFT) where full-potential linearized augmented plane wave (FP-LAPW) was used a basis set with generalized gradient approximation plus Hubbard potential (GGA + U) respectively. Furthermore, investigation of electron charge density is done to analyze the mechanism of structural stability of nitrogen doped MoTe2. DUV + N2 treatment is an effective way to improve the performance of MoTe2 FET.

The statistics of capacitive and diffusive contribution in the supercapattery performance is analyzed via numerical approach. In this regard's strontium phosphide has been synthesized through sonochemical technique whereas PANI is obtained through polymerization. The optimized composite of strontium phosphide and PANI is designated for supercapattery device by coupling it with activated carbon. Structural, morphological, crystallinity, and elemental analysis is carried out through SEM, XRD and EDX. The electrochemical performance in three as well as two electrode assembly is investigated through CV, GCD and EIS. Supercapattery expresses excellent performance by showing 122.4 C/g specific capacity, 28.9 W h/kg energy density and 1020 W/kg power density. This device also delivered outstanding power density of 5100 W/kg in parallel with 10.95 W h/kg energy density. Later, the capacitive/diffusive contribution in the supercapattery is analyzed through a systematic approach. A total of 87.95% diffusive contribution is recorded at the scan rate of 3 mV/s which reaches up to 57.90% at 100 mV/s. On other side capacitive contribution in the device is 12.04% at lower scan rate that raises up to 42.09% at 100 mV/s. The decrease in the diffusive part and increase in the capacitive part is due to the ion's interaction time offered with electrode material at lower and higher scan rates.

Electrical properties of two-dimensional materials can be effected by metal adsorbents and clusters. In this manuscript, we have reported the effects of silver (Ag) nanoparticles on the transport properties of graphene field effect transistor with different diameter and concentrations. Raman spectroscopy is utilized to measure doping level in graphene field effect transistor. The peak positions of G and 2D peaks after doping of Ag nanoparticles shows n-type doping in graphene. Electrical transport properties are measured using four probe technique. N-type doping effect in graphene flakes with Ag nanoparticles is also evident from Dirac point shifting to gate voltages below zero. Electron mobility of graphene field effect transistor is increased from 944.94 cm2 V−1 s−1 to 1430.07 cm2 V−1 s−1 with decreasing diameter of Ag nanoparticles. The same trend is observed with increasing concentration of Ag nanoparticles. These outcomes may play dynamic role to understand the performance of graphene-based sensing devices.

Cerium-doped cobalt spinel ferrite {CexCo2Fe2-xO4 (x = 0, 0.3, 0.5)} electrode nanomaterials have been synthesized for the first time. The role of Ce doping for the enhancement of the performance of the supercapacitor has been discussed briefly. SEM analysis showed the almost spherical grain nanoparticles in the range of 40-220 nm with non-uniform cluster and large agglomeration. EDX analysis represented the chemical composition of pure and cerium-doped spinel cobalt ferrite nanomaterials. In PL studies the predominant UV/visible, violet, and blue emission have been observed which are crucial for LEDs. The electrochemical studies of CexCoFe2-xO4 (x = 0, 0.3, 0.5) electrodes were investigated by using CV, GCD and EIS in 1 M KOH electrolyte solution. The highest specific capacitance (937.50 Fg−1) have been obtained with long cycling life 82.3% retention after 4000th cycles. Hence, the fabricated Ce0.5CoFe1.5O4 electrode is a favorable candidate for super-capacitor applications.

The double perovskites halides are potential materials for renewable energy to meets the demands of the global energy shortage. The structural and thermodynamic stabilities of studied materials are ensured by the Goldsmith tolerance factor (0.86 and 0.91) and negative formation energy. The Poisson and Pugh's ratios show the ductile behaviour of studied compounds. The electronic band gaps 3.42 eV/2.15 eV for Cs2GeCl/Br6 and maximum absorption of light in ultraviolet and visible regions increased their potential for solar cells and other optoelectronic applications. The thermoelectric characteristics are analyzed by thermal to electrical conductivity ratio and figure of merit criteria. The studied materials have figure of merit 0.80 and 0.82 for Cs2GeCl6 and Cs2GeBr6 at room temperature.

The Cu-based oxychalcogenides among p-type transparent conducting materials (TCMs) demonstrate significant results in term of their optoelectronic properties. So, they are being focused on our current study. In this paper, we reported a detailed analysis relating to the spin-dependent electronic and optical properties of Cu-based Lanthanide oxychalcogenides materials, ACuOS (A ​= ​La, Ce and Pr) by means of Density Functional Theory (DFT). We observe a decrease in the energy band-gap values for the substitution of lanthanide La→Pr which was in a fine agreement to the experimental results. The band-gap energy values are concluded to be smaller for the case of spin up in comparison to spin down case. The majority and minority spin cases of the band structures and density of states for the three materials are compared and discussed in detail. We also computed spin-dependent optical parameters like the real and imaginary parts of dielectric function, refractive index, reflectivity, absorption coefficient and the electron energy loss function for radiations up to energy value of 14 ​eV. Our investigated optical parameters for these Cu-based oxychalcogenides reveals dissimilarities for both the spin up and down, which are the outcomes of the energy band-gap variations and also the existence of additional structures closer to the Fermi levels which are mostly due to the lanthanides 4f electrons. Their basic material properties including their crystal structures, optical and electronic properties will be covered, as well as their device applications. Also, the development of performance enhancement strategies including doping and other innovative ways to improve performance is still not satisfactory. This has impeded the development of many devices such as photovoltaics, sensors, and transparent electronics properties of materials.

The study divulges the innovative route to the synthesis of strontium oxide (SrO) nanorods integrated with polyaniline (SrO-PANI) by using physical blending method and utilized for high performance asymmetric supercapacitor. The synthesized nanocomposites (NCs) are initially characterized by using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The electrochemical performance of the NCs is evaluated for energy storage applications. The results demonstrated that the SrO-PANI NCs yield a maximum specific capacity (Qs) of 258 C g−1 at current density of 0.8 A g−1 in three electrode assembly and exhibit better electrochemical stability as compared to PANI and SrO nanorods. Supercapattery device is fabricated by using SrO-PANI NCs. Results reveal that supercapattery device gives an improved energy density of 24 Wh kg−1 and the maximum power density is 2240 W kg−1. Furthermore, the fabricated supercapattery device demonstrated an excellent cyclic stability withholding the capacity of 114% after continues 3000 GCD cycles. The capacitive and diffusive contribution in total capacity of the device is further investigated by using Dunn's model. The advancement of these cost effective NCs are fairly suitable for proficient energy storage devices.

Two dimensional (2D) layered materials such as graphene and transition metal dichalcogenides (TMDCs) have gain profound attention owing to their unique electrical, optical, structural and mechanical properties . These novel features make them promising candidate for the next generation optoelectronic and photonic devices . Here, we demonstrated the gate-voltage dependent current modulation of vertical Au/WS 2 /Gr Schottky barrier . A clear rectification is observed in J-V characteristic curves at different gate-voltage due to asymmetric barriers Au/WS 2 and WS2/Gr. The current modulation is obtained by varying the gate-voltage and the extracted rectification ratios ranging from 2.25 × 103 at −60 V to 1.65 × 103 at +60 V, respectively. Furthermore, the junction is utilized for the photo response at several drain to source and gate voltages which reveals modulation in the photocurrent . The photocurrent detected at V ds 0.5 V is ~24 μA that is enhanced to ~52 μA upon varying the Vds to 1 V. Gate tunable photoresponse of the junction depicts that the photocurrent is enhanced from 16 μA at Vg 20 V to ~17 μA at Vg 60 V. Our results demonstrate an effective way to modulate the current of Schottky junction (Au/WS2 /Gr) by employing gate voltage whereas the tunability in the photocurrent unveil its potential applications in next generation photodetectors .

Hyperbranched Poly(amido amine)s (PAMAM) especially those containing disulfide groups have been highly investigated for DNA condensation, drugs and genes delivery. However, the detailed optical properties of PAMAM, intrinsic fluorescence characteristics and their applications for detection of thiols in pure aqueous medium have not been explored yet. Here we report for the first time the detailed investigation of optical properties of PAMAM and their biosensing application in pure aqueous medium. Three PAMAM named as MBAP (without disulfide group), CBAP and HPAP (with disulfide) groups were chosen, synthesized and characterized. Quantum yields of these PAMAM at different pH value were calculated in pure aqueous medium and all the PAMAM were found to be pH sensitive due to presence of tertiary amine and have shown increase in quantum yields in acidic medium. MBAP was not found to be redox sensitive due to the absence of disulfide group while CBAP has shown low redox sensitivity in aqueous medium because of low water solubility. HPAP has shown high redox sensitivity and high quantum yields hence applied for detection of thiols with the limit of detection of 5.29 mM in pure aqueous medium under physiological conditions. These investigations have not only shown the detailed optical properties of extremely important PAMAM but also broadens their application for bioimaging and biosensing.

A systematic approach has been employed to statistically analyze the Faradaic and non-Faradaic mechanism on electrodes. Two strategies have been adopted for device design, i.e. symmetric and asymmetric, by using the metal oxide synthesized via sonochemical method and activated carbon electrode. Structural and electrochemical characterization have been performed to investigate the morphological and electrochemical properties of electrode material. Both devices are electrochemically examined by using cyclic voltammetry (CV) and Galvanostatic charge discharge (GCD) measurements to evaluate the electrochemical performance. CV curves are further explored to study the capacitive and diffusive contribution in both devices. The diffusive-controlled contribution at low scan rate in asymmetric device is about 65% which is suitable for supercapattery applications while the symmetric device shows 91% diffusive contribution presenting better performance for battery applications. The strategy unveils the high capacitive and diffusive contribution in asymmetric and symmetric devices, respectively. Results reveal that same material can be exploited for supercapattery and battery applications by implementing different device architectures.

The excellent solution-processability of polymers have provoked the interest for their potential applications in cost-effective electronic devices. However, these devices usually have low mobility. The study manifests an innovative approach to enhance the mobility of polymer-based field effect transistors (FETs) by incorporating graphene as an intervening layer between poly [4-(4,4-dihexadecyl-4H-cyclopenta [1,2-b:5,4b′] dithiophen-2-yl)-alt-[1,2,5] thiadiazolo [3,4-c] pyridine] (PCDTPT) channel and dielectric layer dielectric. An intentional discontinuity in the graphene layer was introduced to affirm the role of polymer as channel and graphene as carrier injector. The results divulge the enhancement in the performance of PCDTPT-graphene and PCDTPT-graphene (discontinuous) device as compare to pristine PCDTPT based FET. A significantly high mobility i.e. 13.08 cm2/V.sec is achieved for PCDTPT-graphene hybrid device which is 32 times higher than that of pristine PCDTPT based FET (0.41 cm2/V.sec). These results signify that the incorporation of atomically thin graphene layer is a novel route for fabrication of high mobility solution-processed polymer-based FETs for next generation cost effective and high performance electronic devices.

Schottky-barrier diodes have great importance in power management and mobile communication because of their informal device technology, fast response and small capacitance. In this research, a p-type molybdenum ditelluride (p-MoTe

For the first time, 1D Ni ions doped CdS nanowires (NWs) were synthesized via chemical vapour deposition (CVD). The synthesized Cd0.886Ni0.114S NWs were single crystalline. We have reported here, investigation of optical, electrical and magnetic properties of prepared NWs for optoelectronic and spintronic applications. Successful incorporation of Ni ions in an individual CdS NW has been confirmed through several characterization tools: significant higher angle and phonon modes shift were observed in the XRD and Raman spectra. SEM-EDX and XPS analysis also confirmed the presence of Ni2+ ions. Room-temperature photoluminescence (RT-PL) showed multi-peaks: two emission peaks in the visible region centered at 517.1 nm (green), 579.2 nm (orange), and a broad-band near infrared (NIR) emission centered at 759.9 nm. Herein, the first peak showed 5 nm red-shift upon Ni2+ doping hinting the formation of exciton magnetic polarons (EMPs), and broad-NIR emission was observed in both chlorides and bromides which was assigned to d-d transition of Ni ions whose energy levels lie at 749.51 nm (13342 cm-1) and 750.98 nm (13316 cm-1) are very close to NIR emission. Orange emission was not only remained at same peak position but also its PL intensity significantly enhanced at 78 K and is assigned to d-d transition (3A2g → 1Eg) of Ni2+ ions. It was observed that 11.4% Ni2+ ions doping enhance the conductivity of our sample around 20 times and saturation magnetization (Ms) increases from 7.2 × 10-5 Am2/Kg to 1.17 × 10-4 Am2/Kg which shows promise for optoelectronic and spintronic applications.

© 2018 IEEE. The typical traffic models proposed in literature can be considered as heuristic models since they only reflect the stochastic characteristic of the generated traffic. In this paper, we propose a model for M2M communications that generates the traffic. Therefore, the proposed model is able to capture a wider picture than the state-of-the-art traffic models. The proposed model illustrates the behaviour of M2M uplink communication in a network with multiple-access limited information capacity shared channels. In this paper, we analyzed the number of transmitted packets using the traffic model extracted from our proposed communication model and compared it with the state-of- the-art traffic models using simulations. The simulation results show that the proposed model has a significantly higher accuracy in estimating the number of transmitted packets compared with the liteature model.

Two dimensional (2D) materials based heterostructures have gained profound interest in optoelectronics and electronic technology due to additional functionalities over the individual structures. This study demonstrates the fabrication and characterization of van der Waal heterostructure by selective coverage of graphene (Gr) with tungsten disulfide (WS2). The electrical transport measurements divulge the tweaking of charge carriers in graphene after WS2 coverage. Such architecture provides route towards the formation of heterojunction within graphene FET based on surface charge transfer between Gr/WS2 heterointerface. Furthermore, the exposure of device towards deep ultraviolet light (DUV) enhances the charge transfer mechanism and as a result more pronounced junction is observed. The photoelectrical characterization of heterostructure is also investigated by calculating detectivity (D*), external quantum efficiency (EQE) photoresponsivity (Rλ). Our results suggest that 2D heterostructures in combination with DUV irradiations are more efficient and suitable choice to selectively tune the properties of 2D material-based optoelectronic devices.

Tuning the photoluminescence (PL) and magnetic properties of 1D semiconductor nanostructures is extremely important in processing light, improving the speed and storage capacity for optoelectronic and spintronic applications. Here, we have reported the 1D Cd

For the first time, 1D Ni ion doped CdS nanowires (NWs) were synthesized via chemical vapour deposition (CVD). The synthesized Cd