2017, vol. 38

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http://hdl.handle.net/11652/2836

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Przeglądaj 2017, vol. 38 wg Data wydania

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  • Pozycja
    Comparative study of the influence of the reorganization energy on the hole transport of two four-cyclic arenes
    (Wydawnictwo Politechniki Łódzkiej, 2017) Kania, Sylwester; Kuliński, Janusz; Sikorski, Dominik
    Application of the method of quantum-mechanical calculations allowed the determination of the reorganization energy of the molecules of tetracene and p-quaterphenyl and the estimation of the transfer rate integral between neighbouring molecules present in the solid state. Comparison of the transfer rates for holes with the values of the mobility, obtained experimentally for the polycrystalline tetracene layers and p-quaterphenyl layers vaporized in the vacuum in the similar conditions indicate that the molecule’s structure possess the dominate impact on the conductivity of the thin layers of these compounds.
  • Pozycja
    Comparison of methods for simulation of the optical properties of VCSELs
    (Wydawnictwo Politechniki Łódzkiej, 2017) Więckowska, Marta; Dems, Maciej; Czyszanowski, Tomasz
    This paper presents the differences arising from the use of scalar (Effective Frequency Method) and vector (Fourier’s and Bessel’s Admittance Methods) calculation methods in optical analysis of arsenide Vertical-Cavity Surface-Emitting Lasers (VCSELs). Discussed results demonstrate that the vector methods are more accurate than the scalar one, but also they are more time consuming. By comparing two vector methods, it can be seen that the Bessel’s Admittance Method allows to obtain similar qualitatively and quantitatively results in a slightly shorter time. The calculations were performed for structures with varied aperture radius and its location in the resonant cavity. Moreover, this paper includes the comparison of calculation results for a structure in which there are layers with gradually changing refractive index, and the structure in which these layers are replaced by a layer with a constant average refractive index.
  • Pozycja
    Current dependence of resistances and capacitances in a vertical-cavity surface-emitting laser
    (Wydawnictwo Politechniki Łódzkiej, 2017) Komar, Paulina; Śpiewak, Patrycja; Gębski, Marcin; Lott, James A.; Wasiak, Michał
    Based on the model of impedance and modulation time constants for vertical-cavity surface-emitting lasers (VCSELs) we study the resistances and capacitances of an equivalent circuit as a function of the current flowing through the VCSEL. We observe reduction of some components of the resistance and the capacitance, as well as the modulation time constants for increasing current.
  • Pozycja
    The effect of the dipole moment on hole conductivity of polycrystalline films of two anthracene derivatives
    (Wydawnictwo Politechniki Łódzkiej, 2017) Kania, Sylwester; Kościelniak-Mucha, Barbara; Kuliński, Janusz; Słoma, Piotr; Wojciechowski, Krzysztof
    Hole mobility in the polycrystalline layers of anthrone and anthraquinone differs in one order of magnitude in spite of nearly the same crystalline structure. The origin of this difference was determined with use of the quantum-mechanical calculations carried out at the density functional theory level using the B3lYP functional in conjunction with the 6-311++G(d,p) basis set. Based on theses calculations, we suppose that these difference can result from the presence of the dipol moment in the anthrone molecules.
  • Pozycja
    Subwavelength high contrast gratings as optical sensing elements
    (Wydawnictwo Politechniki Łódzkiej, 2017) Marciniak, Magdalena; Gębski, Marcin; Dems, Maciej; Czyszanowski, Tomasz
    Subwavelength high contrast gratings (HCG) can be used as high reflective mirrors and can be used as mirrors of vertical-cavity surface-emitting lasers. HCG mirrors can be designed in such a way that they are extremely sensitive to environmental changes - changes in the refractive index of ambient substance or changes in the absorption coefficient may cause changes in mirror reflectivity. This phenomenon can be used to detect liquids and gases. In this paper we present analysis of HCG properties. We consider the various HCG mirror designs and the possibilities of detecting gases and liquids.
  • Pozycja
    Scientific Bulletin. Physics No. 1219, vol. 38 (2017)
    (Lodz University of Technology Press, 2017) Lodz University of Technology; Politechnika Łódzka
  • Pozycja
    Sensitivity of tetracene layer as an effect of entanglement
    (Wydawnictwo Politechniki Łódzkiej, 2017) Kania, Sylwester; Kościelniak-Mucha, Barbara; Kuliński, Janusz; Słoma, Piotr; Wojciechowski, Krzysztof
    Application of the method of quantum-mechanical calculations allowed for studies of variability of interactions between molecules of ethanol and tetracene. Entanglement of quantum states is seen during calculations in two ways: as a change of electric dipole moment and as an increase of the basis set superposition error (BSSE) with decreasing distance between molecules under study. There are observed the dependences of the total energy of the system due to the mutual arrangement of the long axes of the molecules and due to the orientation of the bond of the oxygen atom to the carbon atom with respect to the plane of benzene skeleton of tetracene molecule.
  • Pozycja
    Verification of one-dimensional models describing anisotropy of step growth
    (Wydawnictwo Politechniki Łódzkiej, 2017) Izdebski, Marek; Ledzion, Rafał
    Models that allow to obtain directional dependencies of normal velocity of a straight step on the (001) face of Kossel crystal and its edge free energy are reviewed. The dependencies were considered in a wide range of crystal growth conditions, which showed some significant discrepancies between the models and limitations in the scope of their applicability. The results presented concern on one-dimensional kinetic and thermodynamic models of a single step.
  • Pozycja
    Influence of tilted surface alignment on flexoelectric domains in twisted nematic layers
    (Wydawnictwo Politechniki Łódzkiej, 2017) Buczkowska, Mariola; Derfel, Grzegorz
    The small deformations induced by electric field in twisted flexoelectric nematic layers were simulated numerically. The onedimensional (i.e. homogeneous over the whole area of the layer) and two-dimensional (i.e. spatially periodic flexoelectric domains) deformations were considered. It was shown that the periodic deformations do not arise if sufficiently high pretilt angle is imposed by the boundary conditions. The value of pretilt angle necessary for elimination of domains increases with the flexoelectric coefficient e33. This result is of practical meaning because the flexoelectric domains are undesirable from an applicative point of view since they destroy the homogeneous appearance of the area of an excited pixel of a display.