Omita Nanda

Humidity Sensing Response of Poly (3, 4-ethylene dioxythiophene)-poly (styrene sulphonate) and Its Nanocomposites

Poly (3, 4-ethylene dioxythiophene)-poly (styrene sulphonate) (PEDOT:PSS) is the most commonly used conducting polymer in organic LEDs, photovoltaics and sensor applications. We studied the humidity sensing properties of this polymer and its nanocomposites. It has been found that chemically treated single walled carbon nanotubes and PEDOT:PSS polymer nanocomposites shows good humidity sensing properties.

Efficient quasi-solid state dye sensitized solar cell using succinonitrile : thiourea based electrolyte composition

The present work demonstrates the application of a composite gel based electrolyte for the fabrication of quasi solid state dye sensitized solar cells (DSSCs). Two gel electrolyte compositions were prepared using poly-ethylene glycol (PEG), titanium di-oxide (TiO2) and ionic liquids with only succinonitrile (SCN) and succinonitrile : thiourea (SCN : TU). Fabrication of DSSCs was carried out by sandwiching two gel electrolyte compositions between a dye sensitized photo anode and a platinum counter electrode. The electrolyte compositions were characterised using scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) studies. The presence of SCN : TU in the electrolyte introduced an interconnected network with titania-nano clusters embedded uniformly inside the host matrix. EIS and CV analysis demonstrated reduced charge transfer resistance and increased current density values. These results were found to be in accordance with current density–voltage measurements of DSSCs which revealed 5 times enhancement in short circuit current density and approximately 3 times enhanced efficiency of 2.38% with the addition of SCN : TU inside the electrolyte matrix. However, slight reduction in open circuit voltage (from 0.68 V to 0.53 V) on addition of SCN : TU was observed. This may be attributed to downward movement of the quasi Fermi level of titania relative to the redox potential of the electrolyte. These results were also confirmed by absorption spectroscopy analysis. The combination SCN : TU was found to be an efficient additive for quasi solid state electrolyte based DSSC applications.

Solid state dye sensitized solar cells with polyaniline-thiourea based polymer electrolyte composition

The quest for cost effective and efficient solid-state electrolytes is a primary goal for dye sensitized solar cells (DSSCs). The present study describes an experimental approach of synthesizing simple composite electrolytes from iodide-triiodide ions (I−/I3−) incorporated into a polyaniline/thiourea matrix for solid-state DSSC applications. This electrolyte composition can be effectively used to decrease the probability of recombination at the TiO2/electrolyte interface and increase the catalytic process of I3− reduction at the electrolyte/counter electrode interface. The application of the optimized electrolyte in DSSC results in increased open-circuit voltage as well as short circuit current density, thereby increasing the overall efficiency by 73% as compared to the reference electrolyte. The present composition can prove to be a promising redox medium for solid state DSSCs.

Self-powered electrochromic window using green electrolyte

Electrochromic windows are considered as future smart windows for conditioning day light inside the room. Most of the electrochromic windows are fabricated using synthetic electrolytes which require an external power source and are also not always environmental friendly. Therefore there is a need for the utilization of naturally occurring electrolytes and also low power consumption devices. We report a self-powered electrochromic window based on naturally occurring gel electrolyte extracted from aloe vera. Prussian blue and aluminum electrode based electrochromic window was fabricated to test the aloe vera gel as electrolyte. A voltage of 0.8 V appeared across the two conducting electrodes of the electrochromic device and light transmittance was found to change from dark to transparent state on self-biasing. The recovery of the device from transparent to dark state with different external voltages was studied. Aloe vera gel was found to be useful as an electrolyte in smart windows, due to its advantages such as low cost, ease of availability and non–toxicity.Electrochromic windows are considered as future smart windows for conditioning day light inside the room. Most of the electrochromic windows are fabricated using synthetic electrolytes which require an external power source and are also not always environmental friendly. Therefore there is a need for the utilization of naturally occurring electrolytes and also low power consumption devices. We report a self-powered electrochromic window based on naturally occurring gel electrolyte extracted from aloe vera. Prussian blue and aluminum electrode based electrochromic window was fabricated to test the aloe vera gel as electrolyte. A voltage of 0.8 V appeared across the two conducting electrodes of the electrochromic device and light transmittance was found to change from dark to transparent state on self-biasing. The recovery of the device from transparent to dark state with different external voltages was studied. Aloe vera gel was found to be useful as an electrolyte in smart windows, due to its advantages s...

Synthesis and Properties of Inorganic Organic Chloride Based Perovskite

Here we report single step synthesis of lead chloride based organic inorganic hybrid perovskite . Thin films of the material show nanostructured morphology dependent on the fabrication method. Thin films deposited by drop casting method exhibit cubical structures. This morphology changes itself to randomly oriented platelets on spin coating. This evolution of morphology is verified by using scanning electron microscopy (SEM). However as revealed by optical microscopy both the films exhibit identical fluorescence spectra with PL peaks at around 500 nm. Such type of materials may be highly useful in photonic applications requiring varying morphological properties.

Effect of Blocking Layer on the Performance of Dye Sensitized Solar Cells

Dye Sensitized solar cells (DSSC) are a significant stepping stone in the field of photovoltaics . In DSSCs, a blocking layer is generally used in between the conducting electrode and the porous titanium dioxide layer. A compact blocking layer covers the rough surface of anode and reduces the probability of short-circuits between the electrolyte and the photoanode. However, a thick blocking layer can also act as a resistance. Therefore, efficient cells require a careful optimization of its thickness. In the present work, a compact blocking layer has been optimized for DSSCs based on a quasi solid state electrolyte and Eosin B as the sensitizer material. The porous semiconductor oxide layer and the optimized compact blocking layer have been characterized by scanning electron microscopy. In addition, the functionality of the blocking layer in DSSC is verified by solar cell characterizations. A significant enhancement has been obtained in DSSCs with blocking layer as compared to the reference cell.

Synthesis of Zinc Oxide Nanostructures by Chemical Routes

Zinc oxide nanostructures were prepared by chemical route using Zinc nitrate and hexamethylenetetramine as starting material. Two different processes: simple chemical route with and without electrodeposition were carried out for obtaining thin films on glass substrates. Different structures were obtained using the two techniques. SEM images show that zinc oxide prepared by simple chemical route using a seed layer is in the form of uniform structure consisting of nanorods of very short length. On the other hand nano rods of larger dimensions were obtained by the electrodeposition technique on transparent conducting glass plates.