Anusaiya Kaswan

Monodispersed ZnO Nanoparticles and Their Use in Heterojunction Solar Cell

Monodispersed ZnO nanoparticles have been synthesised in ethylene glycol medium using zinc acetate and sodium hydroxide at room temperature through ultrasonic treatment. The monodispersed ZnO nanoparticles were characterized by XRD, TEM, SEM, and optical spectroscopy. The results indicate that ZnO shows the hexagonal wurtzite structure having 8 nm average particle size with the band gap of 3.93 eV. ZnO nanoparticles blended with P3HT show the improvement in the interchains and intrachains ordering as compared to pure P3HT. The power conversion efficiency of P3HT/ZnO solar cell is found to be 0.88%, which is comparable with the result obtained by other researchers.

Electrical conduction mechanism in GeSeSb chalcogenide glasses

Electrical conductivity of chalcogenide glassy system Ge30−xSe70Sbx (x = 10, 15, 20 and 25) prepared by melt quenching has been determined at different temperatures in bulk through the I–V characteristic curves. It is quite evident from results that Poole–Frenkel conduction mechanisms hold good for conduction in these glasses in a given temperature range. The variation in electrical conductivity with composition was attributed to the Se–Sb bond concentration in the Se–Ge–Sb system. Results indicated that Ge5Se70Sb25 showed the minimum resistance. In view of this the composition Ge5Se70Sb25 may be coined as ‘critical composition’ in the proposed series. Also the activation energies of conduction of these glassy alloys have been calculated in higher and lower temperature range using the Arrhenius equation.

Effective thermal conductivity and diffusivity of GeSeSb glasses measured simultaneously as a function of temperature and fit to empirical equations

Abstract Thermal transport properties like effective thermal conductivity (λe) and effective thermal diffusivity (ke) of Ge–Se–Sb chalcogenide glassy alloys were measured simultaneously using transient plane source (TPS) technique from room temperature to 260 °C at normal pressure. Twin pellets of the sample, prepared under a load of 5 ton, were used for these measurements. In the studied temperature range, both λe and ke initially remain almost constant from room temperature to 160 °C and then increase to maxima with further increase of temperature, and thereafter decrease with increasing temperature. This variation has been explained phenomenologically on the basis of variation of phonon mean free path with temperature. An effort has been made to predict this behavior by an empirical relation obtained from polynomial fit of the experimental data. The calculated values of λe and ke are in good agreement with the experimental results over the entire range of temperatures under investigation.