S. P. Nehra

An excellent humidity sensor based on In–SnO2 loaded mesoporous graphitic carbon nitride

A highly sensitive and fast responsive relative humidity (% RH) sensor based on In–SnO2 loaded cubic mesoporous graphitic carbon nitride (g-C3N4) has been demonstrated in this study. The mesoporous In–SnO2/meso-CN nanohybrid was synthesized through template inversion of mesoporous silica, KIT-6, using a nanocasting process. Due to its 3D replicated cubic structure with ordered mesopores, the nanohybrid facilitates the process of adsorption, charge transmission and desorption of water molecules across the sensor surfaces. Consequently, the optimized In–SnO2/meso-CN nanohybrid exhibits excellent response (5 orders change in impedance) in the 11–98% RH range, high stability, negligible hysteresis (0.7%) and superior real time % RH detection performance. Compared to traditional metal oxide based resistive sensors with unique mesoporous/hierarchical/sheet-like morphology, the 3D mesostructured In–SnO2/meso-CN nanohybrid demonstrated a superfast response (3.5 s) and recovery (1.5 s) in the 11–98% RH range at room temperature. These results open the door for breath monitoring and show a promising glimpse for designing mesoporous 2D layered materials in the development of future ultra-sensitive % RH sensors.

Impact of thermal annealing on optical properties of vacuum evaporated CdTe thin films for solar cells

In this paper, the impact of thermal annealing on optical properties of cadmium telluride (CdTe) thin films is investigated. The films of thickness 650 nm were deposited on thoroughly cleaned glass substrate employing vacuum evaporation followed by thermal annealing in the temperature range 250-450 °C. The as-deposited and annealed films were characterized using UV-Vis spectrophotometer. The optical band gap is found to be decreased from 1.88 eV to 1.48 eV with thermal annealing. The refractive index is found to be in the range 2.73-2.92 and observed to increase with annealing treatment. The experimental results reveal that the thermal annealing plays an important role to enhance the optical properties of CdTe thin films and annealed films may be used as absorber layer in CdTe/CdS solar cells.

Effect of annealing on structural and optical properties of thermally evaporated CdSe thin films

In this study, the structural and optical properties of CdSe thin films are undertaken. These thin films were deposited on glass substrate employing thermal evaporation technique and subjected to air annealing at temperature 100°C, 200°C and 300°C. The thickness was verified by ellipsometry and was found to be 445 nm. The results show that the thin films are nanocrystalline in nature and having cubic phase with preferred orientation (111). The calculated crystallographic parameters like inter planner spacing, lattice constant and grain size are in agreement with the standard data. The strain and dislocation density are observed to be varied with annealing while the optical band gap is found to be varied from 1.72eV to 1.89eV.

Influence of temperature on photovoltaic parameters of mono-crystalline silicon solar cell

In this study, the effect of cell temperature on photovoltaic parameters of mono-crystalline silicon solar cell is undertaken. The experiment was carried out employing solar cell simulator at constant light intensity 550W/m2 and with varying cell temperature in the range of 25-60°C. The results show that cell temperature has a significant effect on photovoltaic parameters. The open circuit voltage, maximum power, fill factor and efficiency are found to be decreased with cell temperature while the reverse saturation current and short circuit current are slightly increased. The results are in good agreement with the available literature.

Performance of Single Crystalline Silicon Solar Cell with Irradiance

In this paper, the effect of irradiance on the performance parameters of single crystalline silicon solar cell is undertaken. The experiment was carried out employing solar cell simulator with varying irradiance in the range 115-550W/m2 at constant cell temperature 25°C. The results show that the short circuit current is found to be increased linearly with irradiance and the open circuit voltage is increased slightly. The fill factor, maximum power and cell efficiency are also found to be increased with irradiance. The efficiency is increased linearly at lower irradiance while slightly increased at higher. The results revealed that the irradiance has a dominant effect on the performance parameters. The results are in good agreement with the available literature.

Morphology dependent catalytic activity of TiO2 nanostructures towards photodegradation of Rose Bengal

This work deals with the synthesis of TiO2 nanostructures using sol-gel and hydrothermal method for evaluating their photodegradation performance towards decolorization of Rose Bengal (RB). A combination of characterization techniques including X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM) and UV–Vis spectroscopy were utilized to evaluate the structural, morphological and optical properties of the obtained nanostructures. It was observed that the TiO2 nanoparticles prepared using hydrothermal method were highly crystalline and possess higher band gap value, even when same conditions of temperature, pressure, precursor ratios and solvent amount was kept constant while synthesizing TiO2 nanostructures via sol-gel method. The obvious effect of porous morphology exhibited by TiO2 nanoparticles prepared using hydrothermal route is reflected in its decolorization performance whereby 92.5% of the RB dye solution was degraded in 70 min of irradiation time.