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CoSP approach for the synthesis of blue MoO3 nanoparticles for application as hole transport layer (HTL) in organic solar cells
No full textThe synthesis of MoO3 nanoparticles is reported using a Continuous Spray. Pyrolysis (CoSP) reactor and the influence of zone temperature, precursor concentration on the structural and morphological properties is investigated. The collected nanoparticles are utilized to prepare thin films by spin coating and further annealing at various temperatures. The improvement in morphology, crystallinity and the band gap shift shows the effectiveness of the annealing treatment in creating a proper hole transport layer for device applications. The technique thus allows the film formation using a non-vacuum method well suited for organic solar cells. The CoSP based MoO3 (CoSP_MoO3) films are demonstrated to have equal performance to hole-injection layers composed of thermally evaporated MoO3 (eMoO(3))
Electronic structure of the PLD grown mixed phase MoS2/GaN interface and its thermal annealing effect
No full textWe report the electronic structure of Molybdenum disulfide (MoS2) ultrathin 2D films grown by pulsed laser deposition (PLD) on top of GaN/c-Al2O3 (0001) substrates annealed up to 550 degrees C in an ultrahigh vacuum. Our X-ray photoemission spectroscopy (XPS) study shows that the grown films are mixed phase character with semiconducting 2H and metallic 1T phases. After ultrahigh vacuum (UHV) annealing, the 1T/2H phase ratio is significantly modified and film-substrate bonding becomes the leading factor influencing variation of mixed phase compositions. The semiconducting phase is partially transformed to metallic phase by thermal annealing; suggesting that the metallic phase observed here may indeed have more stability compared to the semiconducting phase. The notable enhancement of the 1T/2H ratio induces significant changes in Ga 3d core level spectra taken from bare GaN and MoS2/GaN sample. The impact of S and/or Mo atoms on the Ga core level spectra is further pronounced with the thermal annealing of grown films. The analysis shows that an enhancement of 1T metallic phase with thermal annealing in MoS2 layers is manifested by the occurrence of new spectral component in the Ga 3d core level spectra with the formation of Ga-S adlayer interaction through the Ga bonding in defect assisted GaN structur
Study of nanosized copper-doped ZnO dilute magnetic semiconductor thick films for spintronic device applications
No full textScreen-printed pure and copper-doped ZnO dilute magnetic semiconductor thick films were casted from chemically co-precipitated zinc oxide and copper-doped zinc oxide nanoparticles followed by sintering at 550 degrees C to obtain desired stoichiometry in spintronic device applications. These thick films were characterized by different analytical techniques to reveal their structure, surface morphology, optical, magnetic and electrical characteristics. The diffraction peaks pertaining to wurtzite structure are observed in XRD patterns of these films, while SEM images show smooth and dense morphology. Infrared transmission and Raman spectra exhibit vibrational bands pertaining to Zn-O-stretching modes and E-2 (high) phonon mode, respectively, in 4000-100 cm(-1) region. The direct bandgap energy of these films derived from diffused reflectance spectroscopy varies in 3.21-3.13 eV range and is supported by PL spectroscopy study. The semiconducting behaviour and activation energy of these thick films has been confirmed by DC conductivity measurements. Electron paramagnetic resonance spectra showed derivative signal of g value 2.0018 in pure ZnO due to oxygen vacancies produced during synthesis and 2.0704 in copper-doped ZnO dilute magnetic semiconductor films
Silver nanoparticles induced alterations in multiple cellular targets, which are critical for drug susceptibilities and pathogenicity in fungal pathogen (Candida albicans)
No full textPurpose: A significant increase in the incidence of fungal infections and drug resistance has been observed in the past decades due to limited availability of broad-spectrum antifungal drugs. Nanomedicines have shown significant antimicrobial potential against various drug-resistant microbes. Silver nanoparticles (AgNps) are known for their antimicrobial properties and lower host toxicity; however, for clinical applications, evaluation of their impact at cellular and molecular levels is essential. The present study aims to understand the cellular and molecular mechanisms of AgNp-induced toxicity in a common fungal pathogen, Candida albicans
Nighttime particle growth observed during spring in New Delhi: Evidences for the aqueous phase oxidation of SO2
No full textAerosol size distributions were measured using a scanning mobility particle sizer (SMPS), and also PM1 (particulate matter <= 1 mu m in aerodynamic diameter) samples were collected in parallel at a representative site in New Delhi during spring in 2013 and 2014. Based on the temporal variation of particle count mean diameter (CMD), sampling periods are characterized as growth events and non-growth events. Particle size distribution measurements suggest that some consecutive nights experienced unique nighttime subsequent growth of particles, which sustained for a longer period. Average particle growth rate measured during growth events was 5.64 +/- 3.03 nm h(-1). Atmospheric trace gas concentrations and meteorological data show that these growth events (nighttime) are influenced by higher concentrations of gases, e.g., NO2 (56.5 +/- 29.7 mu g m(-3)), SO2 (9.34 +/- 1.14 mu g m(-3)) and RH (45.7 +/- 9.5%) than those of non-growth events (daytime) (37.9 +/- 18.6 mu g m(-3), 7.19 +/- 2.08 mu g m(-3) and 37.7 +/- 6.9%, respectively). Further, analysis of PM1 samples collected during the study period shows that the particulate water-soluble organic carbon (WSOC) (12.7 +/- 4.1 mu g m(-3)), NH4+ (9.4 +/- 3.2 mu g m(-3)), SO42- (2.03 +/- 0.70 mu g m(-3)), K+ (1.06 +/- 0.40 mu g m(-3)), and NO2- + NO3- (0.59 +/- 0.36 mu g m(-3)) are the major contributors of particulate mass, wherein NH4+, SO42-, K+, NO2- + NO3- mass concentrations were higher during growth events. Correlation study shows that nighttime aerosol composition during growth (in sub-micron range) events are more enriched by inorganic species (i.e., NH4NO3, (NH4)(2)SO4 and H2SO4 vapors) as compared to organics (i.e., WSOC, does not show much difference in growth events and non events). Our results suggest that nighttime sulfate formation at the site is mostly mediated by high NO2 and NH3 at elevated RH. For the formation of sulfate and other inorganic species, a nighttime atmospheric chemistry is proposed, which is linked to particle growth. Growth events observed typically in nighttime have both biomass burning and anthropogenic influences as indicated by high concentrations of WSOC, K+ and black carbon in PM1 and carbon monoxide in gas phase
Metal-CH3NH3PbI3-Metal Tunnel FET
No full textA novel-gated structure of aluminum (Al)-perovskite (CH3NH3PbI3)-indium tin oxide (ITO), with Al as source and ITO as drain terminals, has been reported. Ambipolar nature of CH3NH3PbI3 has been explored for the device channel. Two Schottky junctions are present at source-channel and channel-drain junctions with barriers of 0.4 and 0.6 eV, respectively. Both, n- and p-type FET-like characteristics have been observed, when the device was biased, accordingly. The triangular tunneling has been observed in the output and transfer characteristics. The device shows a higher current on-off ratio (I-ON/(OFF)) of 10(6) with a steeper and improved sub-threshold swing (SS) of 20 +/- 2 mV/decade for P tunnel field-effect transistor (TFET). However, for N TFET, I-ON/(OFF) of 10(4) with SS of 30 +/- 2 mV/decade has been obtained
Molecular structure, vibrational, optical and second order polarizabilities of (E)-1-(2',4'-Dihydroxy-phenyl)-3-(2,3-dimethoxyphenyl)-propenone chalcone derivative: a quantum computational approach
No full textIn this report, geometrical optimization, spectroscopic analysis, photophysical and nonlinear optical studies of (E)-1-(2',4'-Dihydroxy-phenyl)-3-(2,3-dimethoxyphenyl)-propenone (2,3,4 DHMP) were investigated by utilizing DFT/B3LYP, DFT/CAM-B3LYP, DFT/LC-BLYP, DFT/PBE1PBE, DFT/WB97XD, DFT/TPSS and DFT/M06-2X at 6-31++G** basis set and obtained outcomes are compared. The geometrical parameters are in close covenant with experimental (An excellent concurrence between geometrical parameters and the experimental results was observed). The detailed FT-IR and FT-Raman spectroscopic analyses is carried out. TD-DFT is used to analyze UV-visible spectrum at dissimilar methods and the value of lambda(abs) is observed at similar to 400 nm. Molecular orbitals and electrostatic potential were calculated and discussed. Second-order polarizability was computed which is similar to 21 times larger compared to urea. High value of polarizability makes current compound as a good applicant for NLO applications
Hydrostatic pressure-induced huge enhancement of critical current density and flux pinning in Fe1-xCoxSe0.5Te0.5 single crystals
No full textWe performed a systematic study of the hydrostatic pressure (HP) effect on the superconducting transition temperature (T-c), critical current density (J(c)), irreversibility field (H-irr), upper critical field (H-c2), and flux pinning mechanism in un-doped and 3 at.% Co-doped FeSe0.5Te0.5 crystals. We found that T-c is increased from 11.5 to 17 K as HP increases from 0 to 1.2 GPa. Remarkably, the J(c) is significantly enhanced by a factor of 3 to 100 for low and high temperature and field, and the H-irr line is shifted to higher fields by HP up to 1.2 GPa. Based on the collective pinning model, the delta l pinning associated with charge-carrier mean free path fluctuation is responsible for the pinning mechanism of Fe1-xCoxSe0.5Te0.5 samples with or without pressure. A comprehensive vortex phase diagram in the mixed state is constructed and analysed for the 3 at.% Co-doped sample
Collective dielectric processes at the transition temperature of the Sm-C* and Sm-A* phase in a ferroelectric liquid crystal
Get PDFAn anomalous dielectric relaxation process, called the partially unwound helical mode (p-UHM), is a collective dielectric process apart from the well known Goldstone and soft mode process; it is studied in the smectic C* (Sm-C*) phase and at the transition temperature of the Sm-C*-Sm-A* phase in the ferroelectric liquid crystal (FLC) material. To avoid the surface effect, a thick cell of 40 mu m thickness was prepared with highly rubbed surfaces of the ITO substrates. It has been observed that the dielectric properties in Sm-C* and at the T-c temperature are dominated by the p-UHM process which is dependent on an applied oscillating field in the Sm-C* phase. The probing ac and dc bias field dependences of all these collective dielectric processes have been reported in the Sm-C* and Sm-A* phases of FLC materials
Epitaxial growth of GaN nanostructure by PA-MBE for UV detection application
No full textWe report the growth of lower aspect ratio, nano-island shaped, lower stress and strain facilitated gallium nitride nanostructures (GaN-NS) on Si (111) substrate via plasma assisted molecular beam epitaxy (PAMBE) and fabrication of GaN-NS based UV photo-detection device even with NS's tiny dimensionality. GaN-NS were grown on Si (111) substrate with an inhomogeneous layer of Si3N4 which act as antisurfactant to Ga atoms and also offer localized compressive strain. The developed strain can be relaxed by the growth of inhomogeneously oriented GaN-NS. The three dimension (3D) growth of GaN-NS in real time was observed by in-situ RHEED technique which displays transformation from streaky to spotty pattern. A micro-Raman technique has been employed to elaborate NS's crystallinity and lower stress value which is found be in good agreement with related lower strain as evaluated by HR-XRD spectra. A sharp near band edge emission at 363.2 nm is observed by room temperature photoluminescence measurement which signifies the presence of GaN. Metal semiconductor metal Au-GaN-NS/ Si(111) device was fabricated to specifically analysed its ability to detect harmful ultraviolet radiations (325 nm) with GaN islands of just 26 nm height and 50 nm width. The performance of the fabricated device was analysed at fixed optical power of 13 mW with varying bias voltages (0.4-3 V)