The effect of TiCl4-treated TiO2 compact layer on the performance of dye-sensitized solar cell

In order to prevent the charge recombination at the interface between the transparent-conducting oxide (TCO) substrate and electrolyte, a TiO₂ compact layer was deposited on the substrate by hydrolysis of TiCl₄ aqueous solution. Optimum thickness of the compact layer was found to be ∼25 nm, which showed ∼24% increase in the power-conversion efficiency compared with the bare cell. Impedance spectra indicated that the interfacial charge-transfer resistance of TCO/electrolyte interface was increased by more than a factor of three with the TiO₂ compact layer at 0.4 V. Moreover, the electron-carrier lifetime of the 25 nm-deposited cell was improved by a factor of five compared with the bare cell.     

The Associative Algebras of Conformal Field Theory

Modulo the ideal generated by the derivative fields, the normal ordered product of holomorphic fields in two-dimensional conformal field theory yields a commutative and associative algebra. The zero mode algebra can be regarded as a deformation of the latter. Alternatively, it can be described as an associative quotient of the algebra given by a modified normal ordered product. We clarify the relation of these structures to Zhu's product and Zhu's algebra of the mathematical literature.     

The f-electron contribution to the elastic property of Ce3S4

The elastic constant, C’, of Ce₃S₄ has been measured as a function of temperature. It is shown that the curve is markedly different from that of La₃S₄. Since the only basic difference between the two compounds is the existence of a f-electron in Ce, we propose a theoretical scheme in which the f-electron plays a crucial role. It is shown that the existence of the f-electron in Ce₃S₄ prevents the band Jahn–Teller type structural transition when the temperature is lowered. The theory is consistent with the experiment and also with the theoretically predicted instability of cubic f-electronelements at zero temperature. Received: 5 October 1999 / Accepted: 11 October 1999 / Published online: 24 March 2000     

Electronic transport and carrier concentration in conductive ZnO:Ga thin films

Transparent and conductive Ga-doped ZnO (ZnO:Ga) films were post-annealed after sputter deposition, and their structural and electrical properties were investigated. Post-annealing led to an improvement of crystallinity along the [001] direction, but did not change lateral grain size. Therefore, carrier concentration and electron mobility of films were analyzed as a function of crystallinity. The electrical parameters were obtained with both optical reflectance based on the Drude free-electron model and the Hall method, and similar tendencies were observed within the two methods. Even though the lowest resistivity was demonstrated by the film annealed at 550 °C, the optimum values for carrier concentration and mobility were observed in films with different post-annealing temperatures.     

Fabrication and electro chemical properties of poly vinyl alcohol/para toluene sulfonic acid membranes for the applications of DMFC

The novel acid–base membranes composed of para toluene sulfonic acid (pTSA) as an acidic compound, and poly vinyl alcohol (PVA) as a basic compound were fabricated. The morphological and structural properties of the prepared membranes were analyzed by scanning electron microscopy and Infra red spectroscopy. Inclusion of Glutaraldehyde (GLA) and para toluene sulfonic acid (pTSA) promotes the amorphous character of a polymer which causes the free volume for the movement of ions. Thermal and mechanical stability of the acid–base membranes were influenced by the crosslinking agent glutaraldehyde. By the suitable charge carriers of pTSA, hydrophilic channels were promoted for the composite membranes which ensure the ionic conductivity. A high ionic conductivity-methanol permeability selectivity ratio obtained for the prepared PVA/pTSA membrane influences its viable application in direct methanol fuel cells.     

A simple formalism for the BPS monopole

A simple formalism for the BPS monopole is obtained by generalizing the ADHM construction of multi-instantons to a Hilbert space. Both the potential itself and the Green's functions for different isospin can be obtained with very little effort from the instanton formulae.     

Mass spectra of dual strings

Dual strings seem to correspond uniquely to certain subgroups of the modular group. From three axioms, one of which is a tentative simplicity assumption, a finite number of possible mass spectra is derived, but not yet the corresponding amplitudes. Above space-time dimension 8, this approach yields just the mass spectra of the known models, plus one additional candidate for 10 dimensions. Further models exist probably for dimensions 8, 6, and 4, and perhaps for dimensions 5 and 3. The mass spectrum of one candidate for the “correct model” is determined. It yields only mesons of charge zero, but otherwise the agreement with experiment is amazing.