Muthu Senthil Pandian

Monocrystal growth and characterization study of α- and γ-polymorph of glycine to explore superior performance of γ-glycine crystal

Abstract Optical quality single crystals of α- and γ-polymorph of glycine with respective dimension of 16 × 04 × 04 and 16 × 14 × 08 mm3 have been grown from slow solvent evaporation technique. The single crystal X-ray diffraction (XRD) study has been carried out to confirm the cell parameters, crystal structure and space group of grown polymorphs of glycine crystal. The powder XRD analysis has been performed to investigate the crystalline nature of γ-glycine crystal. The UV-visible spectral analysis has been carried out in the range of 200–900 nm to determine the optical transmittance and band gap of grown crystals. In Kurtz-Perry test, the second harmonic generation efficiency of γ-glycine crystal is found to be 1.4 times higher than KDP crystal material. The emission profile and electronic purity of grown crystals has been examined by means of photoluminescence study. The differential thermal analysis of grown crystals has been undertaken to determine the melting point of grown polymorphs of glycine crystal. The temperature dependent behavior of dielectric parameters of grown crystals has been comparatively investigated within 35–90 °C by means of dielectric analysis.

Fabrication of stable dye-sensitized solar cell with hydrothermally synthesized titanium dioxide nanorods as a photoanode material

TiO2 nanorods have been prepared by hydrothermal method at 170xa0°C for 24xa0h and successfully implemented in a stable solar cell as a photoanode material to replace the conventional nanoparticles which cause the recombination reactions at the interfaces due to a large number of grain boundaries. The synthesized products are characterized by powder X-ray diffraction, Raman and transmission electron microscopy analysis. The performance of the nanorods employed solar cell has been studied under the irradiance of 100xa0mW/cm2. The fabricated device showed a power conversion efficiency of 5.42%. The open-circuit voltage, short-circuit current density and fill factor of the device are 0.647xa0V, 13.64xa0mA/cm2, and 61.5%, respectively. The electrochemical behavior of the fabricated device has been analyzed with electrochemical impedance spectroscopy. The lifetime of the injected electrons in the photoanode network has been found to be 10xa0ms, which was evaluated from Bode phase plot. From the Nyquist plot of the impedance spectrum, lower charge transfer resistance (Rct) has been observed at the TiO2/dye/electrolyte interface. The sealed device was monitored frequently with 500xa0h of the interval. Up to 2500xa0h, no significant drop has been observed in the J–V characteristics.

Influence of SILAR deposition cycles in CdS quantum dot-sensitized solar cells

The cadmium sulfide (CdS) quantum dots (QDs) were deposited on the commercial (Degussa-P25) TiO2 nanostructures by successive ionic layer adsorption and reaction (SILAR) method. Three types of films were prepared with CdS 9, 12 and 15 cycles. The PXRD, UV–Vis–NIR absorption and J–V measurements were taken for the CdS QDs deposited for 9, 12 and 15 cycles and the results were compared. The CdS sensitized electrode prepared using 12 cycles of SILAR produces an efficiency of 1.45% on using a liquid (I−/I3−) electrolyte and platinum counter electrode under the illumination of 100xa0mW/cm2 which shows the best power conversion efficiency compared with CdS 9 and 15 cycles respectively. Total charge collection efficiency was increased upto 12 deposition cycles and it started to decrease beyond 12 cycles. This might be due to the changes in the photo adsorption behavior of CdS QD as a function of deposition cycles.

Investigation of suitable binder combination and electrochemical charge transfer dynamics of vanadium carbide nanoparticles-based counter electrode in Pt-free dye-sensitized solar cell

AbstractnWe have fabricated vanadium carbide counter electrode (CE), and we have investigated suitable binder combination (conductive carbon/N-methyl pyrrolidone (CC/NMP), NMP, CC/IPA (isopropanol)) material for increasing bonding strength, crack-free coated films, high conductivity and highly catalytic activity functions on the fluorine-doped tin oxide (FTO) glass substrate for the redox reaction at the counter electrode of dye-sensitized solar cells (DSSCs). The power conversion efficiency of 3.9% is obtained for vanadium carbide–CC/NMP binder, comparable performance to the traditional Pt-based CE (4.0%). Based on the electrochemical investigation and current–voltage measurement, the comparable efficiency was achieved by the higher current density (Jsc) and lower charge transfer resistance (Rct) due to the CC/NMP binder which is increasing bonding strength between CE materials and FTO. The present investigations open promising ways to the further movement for substantial amount of production of traditional Pt-free DSSC.