Papers by Author: Sandesh R. Jadkar

Abstract: Innovations in materials technology in the fields of photovoltaics play an important role in the paradigm shift from fossil fuels to renewable energy sources. The use of solar energy is one of the most important problems in energy utilization. Dye sensitized solar cell (DSSC) technology has been recognized as a competitor to the well developed thin film solar cells. In the present investigation, we have fabricated a device using natural Lawsone (Heena) dye which was used to sensitize zinc oxide (ZnO) films. ZnO seed layer was deposited using chemical bath deposition and slurry was used to deposit ZnO films followed by sintering at 450°C for 30 minutes in air. Performance of nanostructure ZnO photoelectrode using lawsone dye as a function of residence time in the dye solution was studied. For 20 hour dye loading time, we were observed power conversion efficiency around 0.5% which is more as compared to 5 and 14 hours dye loading time.

Abstract: In this work we report synthesis and characterization of hydrogenated nanocrystalline silicon (nc-Si:H) thin films by plasma chemical vapor deposition (P-CVD) method at 200 0C on glass substrates. Film properties are carefully and systematically investigated as a function of argon (Ar) flow rate. Characterization of these films with Raman spectroscopy revealed that the addition of Ar into SiH4-H2 plasma endorses the growth of crystallinity in the films. The Fourier transform infrared (FTIR) spectroscopic analysis showed that with increasing Ar flow rate the hydrogen bonding in the films shifts from mono-hydride (Si-H) to di-hydride (Si-H2) and (Si-H2)n complexes. The hydrogen content in the films was found < 7 at. % over the entire range of studied Ar flow rate. The band gap of nc-Si:H films was found to be higher than hydrogenated amorphous silicon (a-Si:H) films (> 2 eV). The nc-Si:H films with dark conductivity 1.3x10-7 S/cm having deposition rate as high as 2.5 Å/s and of crystalline fraction 98 % have been obtained.

Abstract: Conducting Polyaniline (Pani)-crooked Gold nanocomposites were synthesized by in situ chemo-oxidative polymerization of aniline with previously made crooked gold nanoparticles by using ammonium per oxidisulphate as oxidizing agent and p-toluene sulphonic acid (p-TSA) as dopant. The formation of nano gold was established by UV-visible spectroscopy with a SPR peak at 512 nm and crooked morphology was confirmed by TEM. Spectroscopic analysis confirmed the formation of the conducting emeraldine salt phase of the polymer. Due to clustering of composite nanoparticles, the polymer composite formed one-dimensional rod-like morphologies. Thermogravimetric analysis revealed a typical three-step decomposition pattern pertaining to polyaniline emeraldine salt. The conductivity of the nanocomposite was found to be lower (2.47 S/cm) than the virgin p-TSA doped polyaniline (5.55 S/cm).

Abstract: Herein, we report the fabrication of anthracene nanostructures and, in turn, their thin films at the air-water interface by recrystallization at the liquid-liquid interface. This method is simple, inexpensive and allows the deposition of anthracene nanoparticulate thin films on large and a variety of substrates. The virgin films were characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Hot Stage Polarizing Microscopy and UV-Visible spectroscopy. Interestingly, it was found that these thin films are comprised of nanosized bushy clusters of anthracene molecules as revealed by TEM. Also, with increase in the thickness of the films, the formation of irregular microtapes was evinced by SEM. The absorption spectra reveals the presence of 2 excitonic peaks for the lowest dip sample (10 dips) whereas the spectra recorded for higher dip samples (20 dips, 30dips, 40dips) closely match with that of pure anthracene in chloroform solution. The dramatic reduction in the melting point as revealed by hot stage polarizing microscopy is the salient feature of the work.