@article{JaroszQuinnStephanetal.2005,
  author    = {Jarosz, Grazyna and Quinn, P. D. and Stephan, Niels and Brehmer, Ludwig},
  title     = {Dielectric properties of zinc phthalocyanine thin films : effects of annealing in air and in N-2},
  issn      = {0040-6090},
  year      = {2005},
  abstract  = {This work presents the effects of ambient conditions, in particular oxygen and humidity, on the dielectric spectra of thin zinc phthalocyanine (ZnPc) films equipped with interdigitated electrodes and the effect of annealing in dry N-2 or in ambient air. The measurements were performed in the frequency range 10(-2)-10(5) Hz. The results indicate that the electric properties of ZnPc films are not only affected by oxygen but also by water vapour the presence of which always leads to the drop in alternating current conductance (ac-conductance). Moreover, at room temperature, the ac-conductance of ZnPc films previously exposed to air exhibits a reversible change with humidity, which makes these films attractive for humidity sensing applications. (C) 2004 Elsevier B.V. All rights reserved},
  language  = {en}
}
@article{PenacoradaSoutodeSajaetal.2005,
  author    = {Penacorada, Florencio and Souto, Jorge and de Saja, J. A. and Brehmer, Ludwig},
  title     = {Brewster angle microscopy and surface potential measurements of Langmuir-Blodgett films of zinc tri(tert-butyl)- 4-sulphophthalocyanine},
  issn      = {0169-4332},
  year      = {2005},
  abstract  = {The formation of a Langmuir monolayer of an amphiphilic derivative of zinc phthalocyanine (Na[(ZnPcSO3)-S-t]) has been studied by means of surface potential technique and Brewster angle microscopy. The experiments were undertaken in order to understand the behaviour of this monolayer with a well-defined surface pressure isotherm. The floating film is described as a truly monomolecular layer formed by very rigid islands in which the phthalocyanine units tend to take on a preferential orientation with their planes perpendicular to the air-water interface, for high values of the surface pressure. (c) 2004 Elsevier B.V. All rights reserved},
  language  = {en}
}
@article{JaroszSignerskiBrehmer2006,
  author    = {Jarosz, Grazyna and Signerski, Ryszard and Brehmer, Ludwig},
  title     = {On dielectric spectra of thin copper phthalocyanine films},
  issn      = {0040-6090},
  doi       = {10.1016/j.tsf.2006.02.035},
  year      = {2006},
  abstract  = {The work presents low signal dielectric spectra of gold/copper phthalocyanine/magnesium and gold/copper phthalocyanine/gold sandwich systems in the 25 Hz-1 MHz frequency range. The performed analysis enables us to distinguish the electrode resistance and the lattice polarization from processes related with electric transport, such as charge carrier relaxation at space charge region of a barrier and charge carrier injection in dielectric response.},
  language  = {en}
}
@book{MuzikanteFonavsBrehmeretal.2005,
  author    = {Muzikante, I. and Fonavs, E. and Brehmer, Ludwig and Stiller, Burkhard},
  title     = {Photoinuced phenomena in corona poled polar organic films},
  year      = {2005},
  abstract  = {Organic materials have received considerable attention because of their large dipole moments and optical nonlinearities. The optically induced switching of material properties is important for studying the optoelectronic effects including second harmonic generation. Organic materials for photonic applications contain chromophore dipole which consist of acceptor and donor groups bridged by a delocalized pi-electron system. Both theoretical and experimental data show a reversible highly dipolar photoinduced intra molecular charge transfer in betaine type molecules accompanied by change of the sign and the value of the dipole moment. The arrangement of polar molecules in films is studied both by atom force microscopy and surface potential measurements. To understand the photo response of these materials, their spectroscopic and electrical properties are studied. The morphology and photoinduced surface potential switching of the self-assembled monolayers and polymer films are investigated. (c) 2005 Elsevier B.V. All rights reserved},
  language  = {en}
}
@book{SmertenkoFenenkoBrehmeretal.2005,
  author    = {Smertenko, P. and Fenenko, L. and Brehmer, Ludwig and Schrader, Sigurd},
  title     = {Differential approach to the study of integral characteristics in polymer films},
  year      = {2005},
  abstract  = {The differential approach is based on the determination of dimensionless differential slope, for instance, of current-voltage characteristics (IVC), I=f(V). This slope (a) is given by formula alpha=d(lgI)/d(lgV). With such definition the ranges of constancy of the a(V) dependency correspond to the part of IVC characterized by the power behaviour (I similar to V-alpha). The differential slope of alpha(V) dependency gamma = d(lg alpha)/dlgV determines the exponent behaviour of curve (I similar to exp {eV(y)/kT}). Processing by the differential approach of the investigated theoretical or experimental characteristics permits us to determine the peculiarity of charge flow mechanisms, temperature behaviour of conductivity, etc. The theoretical base and some applications of differential approach to the investigation of the current-voltage, temperature and degradation characteristics of the polyaniline and poly(p- phenilenevinilene) based structures have been shown. (c) 2005 Elsevier B.V. All rights reserved},
  language  = {en}
}
@article{DimitrievSmertenkoStilleretal.2005,
  author    = {Dimitriev, O. P. and Smertenko, P. S. and Stiller, Burkhard and Brehmer, Ludwig},
  title     = {Polyaniline-transition metal salt complexes: insight into formation mechanisms},
  issn      = {0379-6779},
  year      = {2005},
  abstract  = {Two basic morphologies of emeraldine base of polyaniline-transition metal salt complex films cast from N- methylpyrrolidinone solutions are described. The first morphology consists of grains and the other consists of loose aggregates, respectively. The correlation of the film morphology with formation of precipitate in the complex solution, kinetics of solvent evaporation from the cast film, amount of solvent entrapped in the film, film conductivity, and IR absorption spectra is shown. Two different mechanisms of the complex formation as a result of competition in the polymer- inorganic salt-solvent trio interactions are discussed; the first mechanism results in folding of macromolecules into compact coils being then a core of grains in the complex films, and the second mechanism leads to blending of the polymer chains with solvent giving rise to formation of loose aggregates. (c) 2005 Elsevier B.V. All rights reserved},
  language  = {en}
}
@article{MuzikanteFonavsTokmakovetal.2005,
  author    = {Muzikante, I. and Fonavs, E. and Tokmakov, A. and Cepite, D. and Stiller, Burkhard and Brehmer, Ludwig and Neilands, O.},
  title     = {Optical and electrical properties of oriented thin films of oligomer containing betaine-type moiety in side chain},
  issn      = {0370-1972},
  year      = {2005},
  abstract  = {Non-linear optical and electrical properties of polymer films obtained by dipole orientation of active units are reported. Novel polar oligomer with N-(indan-1,3-dion-2-yl)pyridinium betaine (IPB) as a side group is studied. Orientation of polar groups in oligomer thin films causes an increase of the photo-induced change of surface potential on irradiation in the region of photo-induced electron transfer (PIET) where the IPB group exhibits a reversible change of the value and sign of the dipole moment. At longer wavelengths, the value of the surface potential of the oligomer may be determined by transport of photo-generated charge carriers},
  language  = {en}
}
@article{WongDetertBrehmeretal.2005,
  author    = {Wong, J. E. and Detert, H. and Brehmer, Ludwig and Schrader, Sigurd},
  title     = {Green light-emitting devices based on soluble oligo(phenylenevinylenes)},
  issn      = {0169-4332},
  year      = {2005},
  abstract  = {In this work, we report our investigations on the film-forming properties as well as the optical and electroluminescent characterisations of a series of lateral-substituted soluble oligo(phenylenevinylenes) of various conjugation length. Preliminary investigations show that these materials are potential candidates for use in organic light-emitting devices (OLEDs). Two types of OLEDs were fabricated: single layer (SL) and single heterostructure (SHS), with poly(p-phenylenevinylene) (PPV) as hole transporting layer. Our best results were obtained with single layer device emitting green light with a luminance of 0.18 cd m(-2) and 0.24 cd m(-2) at a driving voltage of 10 V. (c) 2004 Elsevier B.V. All rights reserved},
  language  = {en}
}
@article{BochenkovKarageorgievBrehmeretal.2004,
  author    = {Bochenkov, V. and Karageorgiev, Peter and Brehmer, Ludwig and Sergeev, G. B.},
  title     = {Quenched growth of nanostructured lead thin films on insulating substrates},
  issn      = {0040-6090},
  year      = {2004},
  abstract  = {Lead island films were obtained via vacuum vapor deposition on glass and ceramic substrates at 80 K. Electrical conductance was measured during vapor condensation and further annealing of the film up to room temperature. The resistance behavior during film formation and atomic force microscopy of annealed films were used as information sources about their structure. A model for the quenched growth, based on ballistic aggregation theory, was proposed. The nanostructure, responsible for chemiresistive properties of thin lead films and the mechanism of sensor response are discussed. (C) 2003 Elsevier B.V. All rights reserved},
  language  = {en}
}
@article{WangNespurekRakusanetal.2004,
  author    = {Wang, G. and Nespurek, S. and Rakusan, J. and Karaskova, M. and Schauer, F. and Brehmer, Ludwig},
  title     = {Polarized electrolumineseence from bilayer structures},
  issn      = {1022-1360},
  year      = {2004},
  abstract  = {The photoalignment ability of poly[methyl(phenyl)silylene] (PMPSi) films makes it possible to use them as hole- transporting substrates for the preparation of organic oriented films. A PMPSi layer prepared by spin coating was irradiated, after drying, with linearly polarized UV light. Then, water-soluble hydroxyaluminium phthalocyaninesulfonate [Al(OH)Pc(SO3Na)(1-2)] was deposited by casting. The cell ITO/PMPSi/AI(OH)Pc(SO3Na)(1-2)/Al showed non-linear current- voltage characteristics. For applied voltages higher than 10 V, polarized electroluminescence was observed. Its spectral characteristic consisted of two peaks with maxima at about 320 and 700 nm; their polarized anisotropies R-EL = Phi(parallel to) / Phi(perpendicular to) were ca. 15 and 0.5, respectively},
  language  = {en}
}