24 research outputs found
Photosensitive in wide spectral region composites based on polyphenylenevinylene
Optical and photovoltaic properties of polyphenylenevinylene derivative –
poly(2-methoxy-5-(3-,7-dimethyl-octyloxy)-1,4-phenylenevinylene (MDMO-PPV) and
its composites with high (40 %) concentration polymethine dyes (PD) – meso-Cl and
hexaindoletricarbocyanine (HITC) films have been studied. Two H-aggregates of dyes
with different energies that weakly depend on the molecular structure of dyes, is formed
in MDMO-PPV with PD in composites films. The efficiency of photogeneration of
charge carrier by these aggregates is greater than the efficiency of photogeneration of
charge carriers by the quasi-isolated molecules of dye. It results in substantial expansion
of the absorption region (in comparison with the absorption region of molecules in
solution) and photosensitivity in the side of higher energies. The presence of PD
aggregates in the films MDMO-PPV influences on their photosensitivity that depends on
PD molecular structure. This dependence can be caused by interaction between the
molecules of MDMO-PPV and dye. In composites MDMO-PPV/HITC, the value of
interaction is low and practically does not influence the efficiency of photogeneration of
charge carriers by MDMO-PPV molecules, which give a considerable contribution to
formation of the photovoltage in 2-3 eV regions. The interaction of meso-Cl and
MDMO-PPV molecules is stronger, and this, probably, results in considerable decrease
of photovoltage in the region of the excitation of MDMO-PPV
Fabrication and characterization of solution-processed methanofullerene-based organic field-effect transistors
A differential method of analysis of steady‐state space‐charge‐limited currents: An extension
Electroactive Polysilanes: Metastability of Electronic States in Poly[methyl(phenyl)silylene]
Fabrication and characterization of solution-processed methanofullerene-based organic field-effect transistors
The fabrication and characterization of high-mobility, n-channel organic field-effect transistors (OFET) based on methanofullerene [6,6]-phenyl C61-butyric acid methyl ester using various organic insulators as gate dielectrics is presented. Gate dielectrics not only influence the morphology of the active semiconductor, but also the distribution of the localized states at the semiconductor-dielectric interface. Spin-coated organic dielectrics with very smooth surfaces provide a well-defined interface for the formation of high quality organic semiconductor films. The charge transport and mobility in these OFET devices strongly depend on the choice of the gate dielectric. The electron mobilities obtained are in the range of 0.05-0.2 cm2 V-1 s-1. Most of the OFETs fabricated using organic dielectrics exhibit an inherent hysteresis due to charge trapping at the semiconductor-dielectric interface. Devices with a polymeric electret as gate dielectric show a very large and metastable hysteresis in its transfer characteristics. The observed hysteresis is found to be temperature dependent and has been used to develop a bistable memory element
Reversible Formation of Charge Carrier Traps in Poly(Phenylenevinylene) Derivative due to the Phototransformation of a Photochromic Additive
Charge carrier mobility in sulphonated and non-sulphonated Ni phthalocyanines: experiment and quantum chemical calculations
The objective of this interdisciplinary paper was to study theoretically and
experimentally the electronic part of charge carrier transport in the class
of sodium salts of sulphonated Ni phthalocyanine as candidates for p-type
channels in organic field-effect transistors. These materials were selected
because of their enhanced solubility as compared to their non-sulphonated
counterparts. The values of the field-effect charge carrier mobility
determined on the OFET structures using NiPc(SO3Na)x films were
much higher than the charge carrier mobility obtained on the respective
device prepared from non-substituted phthalocyanine. In order to explain
differences between charge carrier mobility of sulphonated and
non-sulphonated Ni phthalocyanines, quantum chemistry studies of molecular
aggregates were performed. Quantum chemistry modeling of the semiconductive
molecular systems is new and progressive – we highlighted factors at the
molecular level which led to the enhancement of the charge carrier mobility
in systems containing SO3Na groups