Poly -coated transistor

By 1988, a number of devices such as a MOSFET transistor had been developed by the use of poly(acetylene) (Burroughes et al. 1988), but further advances in the following decade led to field-effect transistors and, most notably, to the exploitation of electroluminescence in polymer devices, mentioned in Friend s 1994 survey but much more fully described in a later, particularly clear paper (Friend et al. 1999). The polymeric light-emitting diodes (LEDs) described here consist in essence of a polymer film between two electrodes, one of them transparent, with careful control of the interfaces between polymer and electrodes (which are coated with appropriate films). PPV is the polymer of choice. 

The bridging polymer is a conducting poly(3-methyIthiophene) or polyaniline and the solid state redox conduction between all electrodes is accomplished by a common coating with poly(ethyleneoxide)/Li" CF3S03- or poly(vinyl alcohol)/ The polyaniline based molecular transistor proved as a very sensitive moisture detector it works well in a dry argon atmosphere but in water saturated argon the device cuts out... 

Cui, T. Liang, G. Varahramyan, K. 2003. An organic poly(3,4-ethylenedioxythio-phene) field-effect transistor fabricated by spin coating and reactive ion etching. IEEE Trans. Electron Dev. 50 1419-1422. 

Recently, several molecule-based microelectrochemical devices have been developed by the Wrighton group.(14.15.21-22) A microelectrode array coated with poly(I) results in a microelectrochemical transistor with the unique characteristic that shows "turn on" in two gate potential, Vq, regimes, one associated with the polythiophene switching from an insulator to a conductor upon oxidation and one associated with the v2+ + conventional redox centers. 

The liquid crystallinity of poly(3-alkylthiophene) has been pointed out [121]. Enhancement of crystallinity by molecular alignment in a liquid crystal phase is prominent in poly(2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b] thiophene) exhibiting a lamellar mesophase. When a thin film of the polymer fabricated by the spin-coating method is annealed at 100 °C, domain size remarkably extends from several tens of nanometers to a several micrometers, maintaining molecular alignment within domains because of the thermal motion of the polymer chains. The hole mobility of the thin film transistors based on this polymer reached 0.7 cm2 V-1 s 1 [122]. 

Recently, n-channel transistors of poly(9,9-di-n-octylfluorene-alt-benzothiadia-zole) (51d) have been reported using thin films fabricated by spin-coating.[298] Electron mobilities ranging from 6 x lO. S x 10 cm V s were observed with the use of a 50 nm BCB polymer layer on top of the Si02 dielectric and Ca electrodes. Alternating copolymers containing 1,3,4-heterodiazoles and fluorenes have also been synthesized and show very low n-channel mobilities (2.2 x 10 cm V s for compound 51e).[299]... 

In this work, an ionophore-based solvent polymeric membrane is cast on top of the PEDOT PSS channel in order to obtain an ion-selective organic electrochemical transistor (IS-OECT). The polymeric membrane is composed of 2-nitrophenyl octyl ether (o-NPOE, 57.2% ww), poly(vinyl chloride) (PVC, 27.9% ww), V.. V.. V. . V -i( I i i( ycloli( xyl-3-oxapentanedianii(le (ETH 129, 9.6% ww) and potassium tetrakis(4-chlorophenyl)borate (KTpCIPB, 5.4% ww), where ETH 129 is a Ca2+-selective ionophore. The channel region of the transistor that is coated by the Ca2+-selective membrane is immersed in an aqueous solution containing 0.1 M KC1 as a background electrolyte and... 

Thin film field-effect transistors have been prepared of poly(3-alkyl-thiophenes) by using spin-coating techniques. The devices are used in the determination of the charge carrier mobility p, dc conductivity a, and the carrier concentration p. Poly(3-hexylthiophene) is characterized in a wide temperature range T = 130 - 430 and possible transport mechanisms are discussed. ... 

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