Search

Organic thin-film field-effect transistors (OTFTs) are emerging as attractive candidates for low-price, large-area, and flexible circuit applications. A variety of organic compounds have been utilized as active semiconductor materials for OTFTs, among which phthalocyanine compounds have attracted considerable attention owing to their remarkable chemical and thermal stability as well as good field-effect performance. Here, we review recent results on the phthalocyanine-based OTFTs. The correlation between the crystal packing structure and the charge transport property is discussed, and we conclude with a description of the future prospects for phthalocyanine-based OTFTs. [ABSTRACT FROM AUTHOR]

We present the synthesis and characterization of a fused-ring compound, dithieno[2,3-d:2',3'-d']thieno[3,2-b:4,5-b']dithiophene (pentathienoacene, PTA). In contrast to pentacene, PTA has a larger band gap than most semiconductors used in organic field-effect transistors (OFETs) and therefore is expected to be stable in air. The large π-conjugated and planar molecular structure of PTA would also form higher molecular orders that are conductive for carrier transport. X-ray diffraction and atomic force microscopy experiments on its films show that the molecules stack in layers with their long axis upright from the surface. X-ray photoelectron spectroscopy suggests that there are no chemical bonds at the PTA/Au interlace. OFETs based on the PTA have been constructed, and their performances as p-type semiconductors are also presented. A high mobility of 0.045 cm²/V s and an on/off ratio of 10³ for a PTA OFET have been achieved, demonstrating the potential of PTA for application in future organic electronics. [ABSTRACT FROM AUTHOR]

We report on the fabrication and characterization of field-effect transistor based on an individual multiwalled nitrogen-doped carbon nanotube. Our measurements show that the N-doped carbon nanotubes have n-type properties. The contact properties of the tube and Pt electrodes are also studied in detail. Temperature dependence of two-terminal transport experiments suggests that transport is dominated by thermionic emission and tunneling through a 0.2 eV Schottky contact barrier. [ABSTRACT FROM AUTHOR]

The authors report on the organic field-effect transistors based on copper phthalocyanine with a inserted layer of molybdenum oxide (MoO3). After applying a positive gate voltage of 100 V, the threshold voltage had a large shift from -11.8 to +66.2 V and the device operating model was changed from the enhancement model into the depletion one. A possible mechanism is believed to be originated from the stored charges in the interface between the thin MoO3 layer and the active layer. Largely reversible shift in the threshold voltage and retention time were also obtained in the devices by the programs used. [ABSTRACT FROM AUTHOR]

Employing 5,5′-bis-biphenyl-dithieno[3,2-b:2′,3′-d]thiophene (BPDTT) as semiconducting layer and poly(vinyl alcohol) (PVA) as gate dielectric layer, we have fabricated organic thin-film transistors. These devices exhibit excellent field-effect performances with a high mobility of up to 0.6 cm2/V s and a very low operating voltage (<1 V) at room temperature. The single crystal of BPDTT was grown and analyzed. The high performances are mainly attributed to the close herringbone packing of BPDTT molecules and the high homogeneity between PVA and BPDTT molecules. [ABSTRACT FROM AUTHOR]

We fabricate single-walled carbon nanotube field-effect transistors (SWNT FETs) with a simple, low-cost, high-efficiency, and solution-based orientational self-assembly method. The SWNT was first functionalized with thiol groups, then suspended in an N,N-dimethylformamide solution, and finally self-assembled on predefined gold contact pads by an orientational N2 blow. A relatively high mobility of 9.2×102 cm2/V s and an on/off ratio greater than 105 at a bias voltage of -1 V have been achieved as a result of directly covalent interaction between end-thiolated SWNT and gold contacts, which favors the fabrication of SWNT FETs as compared to the SWNT FETs bearing the similar geometry but relies on random deposition. Therefore, this orientational self-assembly approach should be a valuable tool in the mass fabrication of high-performance SWNT FETs and SWNT-based molecular-scale electronic devices. [ABSTRACT FROM AUTHOR]

The article discusses the research on the excellent electrical properties of low-cost organic transistors and inverters with chemical modified bottom electrodes. Study reveals, compatibility on energy of electrodes and organic semiconductors were important on forming a ohmic contact for efficient charge injection. However, semiconductors and gate dielectrics must be stable to prevent chemical reactions which could interfere.

Two trifluoromethyltriphenodioxazines were efficiently synthesized as active materials for n-type organic field-effect transistors, and their optical and electrochemical properties were characterized. Air-stable and high-performance thin film transistors based on the two compounds were fabricated. [ABSTRACT FROM AUTHOR]

This article focuses on a self-assembled nano optical switch and transistor based on a rigid conjugated polymer, thioacetyl-end-functionalized Poly(para-phenylene ethynylene) (PPE). Nanometer-scale devices, as the next generation devices of electronics, have experienced worldwide attention and rapid development recently. However, few reports have dealt with the fabrication of nanometer-scale devices by using conjugated polymers, although the combination of nanometer-scale devices and polymers will not only extend conjugated polymers to nanoelectronics but also elucidate the behaviors of polymer molecules at the nano/molecular level such as electron transport through polymer molecules. PPE is expected to possess not only ideal conductivity but also ideal rigidity. The authors have synthesized a derivative of PPEs with thioacetyl end groups and demonstrated its ideal rigidity and connectivity.