Natural dye-based photoelectrode for improvement of solar cell performance

In the present paper, photovoltaic studies of dye-sensitized solar cells (DSSCs) based on betacyanin/TiO₂ and betacyanin/WO₃–TiO₂ have been done. The cell performances were compared through I–V curves and wavelength dependant photocurrent measurements for the two new types of DSSCs. The TiO₂-coated DSSC showed the photovoltage and photocurrent of 300 mV and 4.96 mA/cm², whereas the cell employing WO₃–TiO₂ photoelectrode showed the values 435 mV and 9.86 mA/cm², respectively. The conversion efficiency of TiO₂ based dye-sensitized solar cell was found to be 0.69 %, while WO₃–TiO₂-based cell exhibited a higher conversion efficiency of 2.2 %. The better performance of the WO₃–TiO₂ dye-sensitized solar cell photoelectrode is thought to be due to an inherent energy barrier at the electrode/electrolyte interface leading to the reduced recombination of photoinduced electrons.     

Radiation grafting of acrylonitrile on ethylene-propylene diene terpolymer rubber: Optimization of grafting parameters and oil resistance properties

Radiation induced grafting of acrylonitrile (ACN) on ethylene-propene diene terpolymer (EPDM) rubber film was investigated by mutual radiation grafting technique. Effect of experimental variables viz. radiation dose, dose rate, type of solvent and monomer content on extent of grafting was studied. From the kinetic studies a mathematical relation R _g α[M]^0.7 D ^0.68 showing non-linear relationship for rate of grafting with monomer concentration and dose was deduced. The grafted samples showed increased hardness and oil resistance.     

Information patterns and Nash equilibria in extensive games — II

In Part I of this paper we introduced extensive games with a non-atomic continuum of players. It was shown that the Nash plays (outcomes) are invariant of the information patterns on the game, provided that no player's unilateral change in moves can be observed by others. This led to an enormous reduction in the Nash plays of the these games, as exemplified in the anti-folk theorem. Our concern in this sequel is to develop a finite version of these results.     

Peripheral phonons and phonon conductivity of the doped semiconductor

The percentage contribution of the peripheral phonons towards the total phonon conductivity of P-doped Ge has been studied with the help of the Ziman expression of the electron-phonon scattering relaxation rate and the Callaway integral of the lattice thermal conductivity. It is found that the percentage contribution of the peripheral phonons increases with the increase of temperature. The entire study is limited to the temperature range 1–5 K.     

On the uniqueness of the Shapley value

L.S. Shapley [1953] showed that there is a unique value defined on the classD of all superadditive cooperative games in characteristic function form (over a finite player setN) which satisfies certain intuitively plausible axioms. Moreover, he raised the question whether an axiomatic foundation could be obtained for a value (not necessarily theShapley value) in the context of the subclassC (respectivelyC′, C″) of simple (respectively simple monotonic, simple superadditive) gamesalone. This paper shows that it is possible to do this. Theorem I gives a new simple proof ofShapley's theorem for the classG ofall games (not necessarily superadditive) overN. The proof contains a procedure for showing that the axioms also uniquely specify theShapley value when they are restricted to certain subclasses ofG, e.g.,C. In addition it provides insight intoShapley's theorem forD itself. Restricted toC′ orC″, Shapley's axioms donot specify a unique value. However it is shown in theorem II that, with a reasonable variant of one of his axioms, a unique value is obtained and, fortunately, it is just theShapley value again.     

Diffusion-induced modulational instability in magnetised semiconductor plasmas: effect of carrier heating

The present paper is aimed to the exploration of modulational amplification in transversely magnetised diffusive semiconductors. By considering that the origin of modulational interaction lies in the third-order optical susceptibility c⁽³⁾\chi^{(3)} arising from the nonlinear diffusion current density and using coupled mode theory, an analytical investigation of frequency modulational interaction between co-propagating laser beams and internally generated acoustic mode is presented. We have studied the steady state and transient amplification characteristics of modulated waves arising in the transversely magnetised semiconductor plasmas. The effect of carrier heating adds new dimensions to the present study. The heating effect reduces the required threshold amplitude of wave and enhances steady-state as well as transient gain of the generated acoustic mode.     

Coherence characteristics of light-emitting diodes

We report the measurement of coherence characteristics of light-emitting diodes (LEDs). Experiments were performed using red and green color LEDs directly illuminating the Young's double slit kept in the far-zone. Fourier transform fringe analysis technique was used for the measurement of the visibility of interference fringes from which the modulus of degree of spectral coherence was determined. Low degree of spectral coherence, typically 0.4 for red and 0.2 for green LED with double-slit separation of 400 μm was observed. A variable slit was then kept in front of the LEDs and the double slit was illuminated with the light coming out of the slit. Experiments were performed with various slit sizes and the visibility of the interference fringes was observed. It was found that visibility of the interference fringes changes drastically in presence of variable slit kept in front of LEDs and a high degree of spectral coherence, typically 0.85 for red and 0.8 for green LED with double-slit separation of 400 μm and rectangular slit opening of 500 μm was observed. The experimental results are compared with the theoretical counterparts. Coherence lengths of both the LEDs were also determined and it was obtained 5.8±2 and 24±4 μm for green and red LEDs, respectively.