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Surface Morphology of Polyimide Thin Film Dip-Coated on Polyester Filament for Dielectric Layer in Fibrous Organic Field Effect Transistor

Rambausek L., Bruneel E., Van Driessche I., Van Langenhove L.

Autex Research Journal

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2014

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Vol. 14, no. 3

152--160

EN

The idea of wearable electronics automatically leads to the concept of integrating electronic functions on textile substrates. Since this substrate type implies certain challenges in comparison with their rigid electronic companions, it is of utmost importance to investigate the application of materials for generating the electronic functions on the textile substrate. Only when interaction of materials and textile substrate is fully understood, the electronic function can be generated on the textile without changing the textile’s properties, being flexible or stretchable. This research deals with the optimization of the dielectric layer in a fibrous organic field effect transistor (OFET). A transistor can act as an electrical switch in a circuit. In this work, the polyimide layer was dip-coated on a copper-coated polyester filament. After thoroughly investigating the process conditions, best results with minimal thickness and roughness at full insulation could be achieved at a dip-coating speed of 50 mm/min. The polyimide solution was optimal at 15w% and the choice for the solvent NMP was made. In this paper, details on the pre-treatment methods, choice of solvent and dip-coating speed and their effect on layer morphology and thickness, electrical properties and roughness are reported. Results show that the use of polyimide as a dielectric layer in the architecture of a fibrous OFET is promising. Further research deals with the application of the semiconductor layer within the mentioned architecture, to finally build an OFET on a filament for application in smart textiles.

2

Hole transport in organic field-effect transistors with active poly(3-hexylthiophene) layer containing CdSe quantum dots

Bielecka U., Lutsyk P., Nyk M., Janus K., Samoc M., Bartkowiak W., Nespurek S.

Materials Science Poland

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2013

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Vol. 31, No. 2

288--297

EN

Hybrid field-effect transistors (FETs) based on poly(3-hexylthiophene) (P3HT) containing CdSe quantum dots (QDs) were fabricated. The effect of the concentration of QDs on charge transport in the hybrid material was studied. The influence of the QDs capping ligand on charge transport parameters was investigated by replacing the conventional trioctylphosphine oxide (TOPO) surfactant with pyridine to provide closer contact between the organic and inorganic components. Electrical parameters of FETs with an active layer made of P3HT:CdSe QDs blend were determined, showing field-effect hole mobilities up to 1.1×104 cm2 /Vs. Incorporation of TOPO covered CdSe QDs decreased the charge carrier mobility while the pyridine covered CdSe QDs did not alter this transport parameter significantly.

3

Comparative study on different annealing methods and choice of solvent in organic field effect transistors based on Poly(3-hexylthiophene)

Chua C. L.

Materials Science Poland

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2013

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Vol. 31, No. 3

325--330

EN

A simple approach to study the effect of processing on the charge carrier mobility in an organic field effect transistor (OFET) based on regioregular poly(3-hexylthiophene) (RR P3HT) is investigated in this paper. It is found that different processing conditions can induce different degrees of hysteresis, which is well correlated with the charge mobility where lower hysteresis represents higher stability and hence higher charge mobility. Solvent annealing tends to create large nano-scale pinholes in P3HT which degrade the mobility.

4

Ambipolar injection into pentacene field effect transistor observed by time-resolved optical second harmonic generation imaging

Manaka T., Nakao M., Lim E., Iwamoto M.

Materials Science Poland

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2009

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Vol. 27, No. 3

709--717

EN

Ambipolar carrier injection from gold electrode into pentacene was investigated by time-resolved optical second harmonic generation (TRM-SHG) imaging. Smooth hole injection is verified by rapid decrease of the SHG intensity at the electrode edge, indicating the absence of an injection barrier. In contrast, TRM-SHG results clearly indicated the presence of electron injection from the high-work function metal into the electrode, though after injection electrons were trapped in the channel and could not contribute to the conduction. Transient electric field distribution due to the injected holes and electrons were evaluated based on the SHG intensity distribution.

5

Alternate Copolymer of 3,4-Dioctyloxythiopheneand 2,2'-Bithiophene: Synthesis, Electronic and Spectroelectrochemical Properties

Pokrop R., Kasprzyk-Młynarczyk I., Zagorska M., Wielgus I., Mieczkowski J., Verilhac J., Wery J., Louarn G., Pron A.

Polish Journal of Chemistry

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2007

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Vol. 81, nr 5-6

731-744

EN

Anew electroactive polymer has been prepared by oxidative (electrochemical or chemical) polymerization of 3,4-dioctyloxy-2,2':5',2''-terthiophene. The polymer (PDOTT) is photoluminescent, emitting green light in solution and red light in the solid state. It can be used for the fabrication of organic field effect transistors, however the measured charge carriersmobilities in the transitor configuration ( = 7×10–6 cm2 V–1s–1) are lower than those found for the best polymers reported in the literature. PDOTT is much more promising for electrochemical and electrochromic applications since it shows perfectly reversible spectral response to potential switching. Moreover, in its doped state PDOTT is a strong near infrared absorber.

6

Organic field effect transistor with zinc phthalocyanine

Metel E., Jarosz G.

Scientific Bulletin. Physics / Lodz University of Technology

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2006

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Vol. 26

67-71

EN

Output characteristics of an organic field effect transistor with zinc phthalocyanine are presented. As a substrate highly conductive silicon wafers with an insulation layer of silicon dioxide (SiO2) on the top and gold source-drain electrodes on the SiO2 have been used. The field effect mobility of holes estimated from the lower range of source-drain voltage (linear regime) was 9x10-4 cm2/(Vs).

PL

W pracy przedstawiono wyniki badań doświadczalnych organicznego tranzystora polowego z warstwą ftalocyjaniny cynku. Jako podłoża zastosowano wysoko domieszkowane wafle krzemu pokryte warstwą tlenku krzemu (IV) o grubości 100 nm, na którą techniką fotolitograficzną była naniesiona struktura elektrod (tzw. geometria dolnych kontaktów). Złote elektrody źródła i drenu tworzyły kanał o długości 5 µm (jest to odległość między elektrodą źródła i elektrodą drenu) i szerokości 1048 µm. Warstwy ftalocyjaniny cynku o grubości 60 nm naparowywano na podłoże ze średnią szybkością 0.1 Å/s pod wysoką próżnią (10-6 mbar). Pomiary prowadzono w temperaturze pokojowej w atmosferze powietrza. Obejmowały one zależności natężenia prądu źródło-dren w funkcji napięcia źródło-dren przy różnych stałych wartościach napięcia źródło-bramka. W obszarze liniowym charakterystyk wyznaczono kondunktację kanału tranzystora, na podstawie której następnie oszacowano ruchliwość dziur w badanych warstwach ftalocyjaniny cynku.