Natural resin shellac as a substrate and a dielectric layer for organic field-effect transistors

2013 ◽  
Vol 15 (6) ◽  
pp. 1473 ◽  
Author(s):  
Mihai Irimia-Vladu ◽  
Eric Daniel Głowacki ◽  
Günther Schwabegger ◽  
Lucia Leonat ◽  
Hava Zekiye Akpinar ◽  
...  
Keyword(s):  
Dielectric Layer ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Organic Field Effect Transistors ◽  
Natural Resin

Flexible organic field-effect transistors fabricated by the electrode-peeling transfer

2003 ◽  
Vol 769 ◽  
Author(s):  
Takeshi Yasuda ◽  
Katsuhiko Fujita ◽  
Tetsuo Tsutsui
Keyword(s):  
Dielectric Layer ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Flexible Substrate ◽  
Chemical Vapor ◽  
Solid Substrate ◽  
Semiconductor Material ◽  
Organic Field Effect Transistors ◽  
Gate Electrode ◽  
Micro Patterning

AbstractWe report a simple and mild fabrication of flexible organic field-effect transistors (OFETs) by an electrode-peeling transfer method. Firstly, fine patterns of source-drain metal electrodes were formed on a solid substrate, where a micro-patterning process such as photolithography is applicable. An organic dielectric layer (poly-chloro-p-xylylene) was deposited by a chemical vapor deposition. Then patterned gate electrode was deposited using a shadow mask. On the top surface of the gate electrode, another adhesive flexible substrate was fixed and the stack of the flexible substrate/gate electrode /dielectric layer /source-drain electrode was peeled away from the solid substrate. The peeling-transfer was completed with a help of a self-assembled monolayer of n-decyl mercaptan as a connecting buffer layer between the gold electrodes and the dielectric layer. Then an organic semiconductor material was deposited on the fresh peeled-off surface on the flexible substrate. When pentacene was used as the semiconductor material, the OFETs exhibited a hole mobility of 0.1 cm2/Vs and a current on/off ratio of 105.

scholarly journals Polarization-induced transport in ferroelelctric organic field-effect transistors

2019 ◽  
Author(s):  
◽  
Amrit Prasad Laudari
Keyword(s):  
Organic Semiconductors ◽  
Small Molecule ◽  
Dielectric Layer ◽  
Field Effect ◽  
Polyvinylidene Fluoride ◽  
Carrier Mobility ◽  
Field Effect Transistors ◽  
Organic Field Effect Transistors ◽  
Sensing Applications ◽  
Organic Fets

In this research we study the role of ferroelectric dielectrics in organic field-effect transistors (FETs) to understand the mechanism of charge transport in organic semiconductors. The ferroelectric nature of the polymer, poly(vinylidene fluoride) (PVDF)), has been known for over 45 years. However, its role in interfacial transport in organic/polymeric FETs is not that well understood. PVDF and its copolymer, polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE), as a dielectric in organic FETs is a perfect test-bed for conducting transport studies where a systematic tuning of the dielectric constant with temperature may be achieved. By choosing small molecule organic semiconductors -- pentacene and 6,13 bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene) -- along with a copolymer PVDF-TrFE as the dielectric layer, the FET characteristics are monitored as a function of temperature. Pentacene FETs show a weak temperature dependence of the charge carrier mobility in the ferroelectric phase of PVDF-TrFE, which is attributed to polarization fluctuation driven transport resulting from a coupling of the charge carriers to the surface phonons of the dielectric layer. A negative coefficient of carrier mobility is observed in TIPS-pentacene upwards of 200 K with the ferroelectric dielectric, while an activated transport is observed with non-ferroelectric dielectrics. We show that this behavior is correlated with the nature of the trap states in TIPS-pentacene. We also developed the method of dipole engineering of the PVDF-TrFE films to enhance the properties of organic FETs. PVDF-TrFE, despite its applications in a vast range of work (including as a gate dielectric in organic FET and sensing applications) poses concerns such as higher conductivity compared to other polymer non-ferroelectric dielectrics. We have come up with new methods of electrical poling the dielectric layer to enhance FET performance as well as reduce gate leakage issues. We demonstrate the effect of polarization rotation in PVDF-TrFE on the performance of small-molecule-based organic FETs. The subthreshold swing and other transistor parameters in organic FETs can be controlled in a reversible fashion by switching the polarization direction in the PVDF-TrFE layer. We further demonstrate a novel method of selective poling of the dielectric layer. By using solution processed TIPS-pentacene as the organic semiconductor, it is shown that textured poling of the PVDF-TrFE layer dramatically improves FET properties compared to unpoled or uniformly poled ferroelectric films. The texturing is achieved by first vertically poling the PVDF-TrFE film and then laterally poling the dielectric layer close to the gate electrode. TIPS-pentacene FETs show on/off ratios of 105 and hole mobilities of 1 cm2/Vs under ambient conditions with operating voltages well below-4 V. This research opens prospects of achieving low-operating FETs without any expensive patterning techniques.

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