The Discovery and Development of Conducting Polymers The Scope of This Historical Overview Introduction An Early Example: Polyaniline The First Electrically Conductive Poly(Heterocycle): Polypyrrole The Fundamental Breakthrough: Doped Polyacetylene Conductive Polymers versus Metals and Insulators Metals, Semiconductors, and Insulators Conjugated Polymers Temperature-Dependent Conductivity Order and Disorder Polythiophenes: A Chance for Maximum Conductivity? Oxygen-Substituted Polythiophenes A Short History of the PEDOT Invention The Synthesis of EDOT Monomer, and Its Physical and Chemical Properties Monomer Synthesis Physical Properties Chemical Properties From EDOT to PEDOT: Oxidative Polymerization and Other Routes Oxidative Polymerization and Doping "Self-Oxidation" of EDOT Halogen Derivatives The Organometallic Route to PEDOT Neutral, Undoped PEDOT by Oxidative Polymerization Counterions for PEDOT Counterions in Electrochemically Polymerized PEDOT Counterions in Chemically Polymerized PEDOT The In Situ Polymerization of EDOT to PEDOT Synthesis of In Situ PEDOT Properties of In Situ PEDOT In Situ Polymerization of EDOT Derivatives and Relatives PEDOT: PSS PEDOT: PSS Dispersions Properties of PEDOT: PSS Secondary Doping Applications Solid Electrolyte Capacitors Through Hole Plating for Printed Wiring Boards ITO Substitution Antistatic Coatings Electroluminescent Lamps Organic Light Emitting Diodes (OLEDs) PEDOT:PSS in Organic Solar Cells Electrochromic Behavior Organic Field-Effect Transistors Technical Use and Commercial Aspects EDOT and PEDOT Derivatives with Covalently Attached Side Groups EDOT-CH2OH and Its Derivatives EDOT-CH2Cl and Its Follow-Up Products Alkyl EDOTs Water Soluble, "Self-Doping" EDOT Derivatives XDOTs, EDXTs, EDOXs, and 2(5)-X(2)-EDOTs: Ring Size Variations, Heteroanalogs, and Derivatives of EDOT with Substituents at the Thiophene Ring 3,4-Methylenedioxythiophene (MDOT) ProDOT (Propylenedioxythiophene) Derivatives Vinylenedioxythiophene (VDOT) and Benzo-EDOT 3,4-Ethyleneoxythiathiophene (EOTT) 3,4-Ethylene dithiathiophene (EDTT) 3,4-Ethylenedioxypyrrole (EDOP) and Its Derivatives 3,4-Ethylenedioxyselenophene (EDOS) 2,5-Disubstituted EDOT Derivatives [2(,5)-X(2)-EDOTs] The Electrochemical Behavior of EDOT and PEDOT

PEDOT : Principles and Applications of an Intrinsically Conductive Polymer

The low-loss wide bandwidth capability of opto-electronic systems makes them attractive for the transmission and processing of microwave signals, while the development of high-capacity optical communication systems has required the use of microwave techniques in optical transmitters and receivers. These two strands have led to the development of the research area of microwave photonics. This paper reviews the development status of microwave photonic devices, describes their systems applications, and suggests some likely areas for future development

Microwave Photonics

Over the past three decades, significant research efforts have focused on improving the charge carrier mobility of organic thin-film transistors (OTFTs). In recent years, a commonly observed nonlinearity in OTFT current-voltage characteristics, known as the "kink" or "double slope," has led to widespread mobility overestimations, contaminating the relevant literature. Here, published data from the past 30 years is reviewed to uncover the extent of the field-effect mobility hype and identify the progress that has actually been achieved in the field of OTFTs. Present carrier-mobility-related challenges are identified, finding that reliable hole and electron mobility values of 20 and 10 cm2 V-1 s-1 , respectively, have yet to be achieved. Based on the analysis, the literature is then reviewed to summarize the concepts behind the success of high-performance p-type polymers, along with the latest understanding of the design criteria that will enable further mobility enhancement in n-type polymers and small molecules, and the reasons why high carrier mobility values have been consistently produced from small molecule/polymer blend semiconductors. Overall, this review brings together important information that aids reliable OTFT data analysis, while providing guidelines for the development of next-generation organic semiconductors.

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Recent Progress in High-Mobility Organic Transistors: A Reality Check.

This paper is divided into two major parts. Following a brief introduction that establishes some definitions and assumptions, Section II updates our earlier study on the limits of the RF performance of optical links. Section III reviews progress since our 1997 review paper in the development of devices enabling link performance closer to these limits, including (but not limited to): 1) cascade lasers that permit broad-band direct modulation links with gain >0 dB; 2) injection-locked edge- and surface-emitting lasers at 1300 and 1550 nm with modulation frequency responses as great as 40 GHz; 3) modulators with improved performance, especially electroabsorption modulators that now have switching voltages as low as 0.36 V, or handle optical powers as great as 60 mW, or have bandwidths as great as 50 GHz (but not all three of these in one device yet); and 4) high-speed photodetectors with high saturation currents, e.g., a 20-GHz device with a saturation current of 90 mA and a 55-GHz device with saturation at 50 mA. We conclude in Section IV by summarizing the component developments necessary for higher performance RF-over-fiber links, i.e.: 1) semiconductor lasers (for direct modulation) that have higher slope efficiency and bandwidth and lower relative intensity noise (RIN) at reasonable bias current levels; 2) continuous wave (CW) lasers (for external modulation) with higher fiber-coupled power and lower RIN; 3) higher frequency lower loss external modulators with more linear transfer functions and lower V/sub /spl pi// that can withstand larger CW optical powers; and 4) photodetectors with higher responsivity and bandwidth that respond linearly even when illuminated by greater average optical powers.

Limits on the performance of RF-over-fiber links and their impact on device design

A high-mobility organic semiconductor employed as the active material in a field-effect transistor does not guarantee per se that expectations of high performance are fulfilled. This is even truer if a downscaled, short channel is adopted. Only if contacts are able to provide the device with as much charge as it needs, with a negligible voltage drop across them, then high expectations can turn into high performances. It is a fact that this is not always the case in the field of organic electronics. In this review, we aim to offer a comprehensive overview on the subject of current injection in organic thin film transistors: physical principles concerning energy level (mis)alignment at interfaces, models describing charge injection, technologies for interface tuning, and techniques for characterizing devices. Finally, a survey of the most recent accomplishments in the field is given. Principles are described in general, but the technologies and survey emphasis is on solution processed transistors, because it is our opinion that scalable, roll-to-roll printing processing is one, if not the brightest, possible scenario for the future of organic electronics. With the exception of electrolyte-gated organic transistors, where impressively low width normalized resistances were reported (in the range of 10 Ω·cm), to date the lowest values reported for devices where the semiconductor is solution-processed and where the most common architectures are adopted, are ∼10 kΩ·cm for transistors with a field effect mobility in the 0.1-1 cm(2)/Vs range. Although these values represent the best case, they still pose a severe limitation for downscaling the channel lengths below a few micrometers, necessary for increasing the device switching speed. Moreover, techniques to lower contact resistances have been often developed on a case-by-case basis, depending on the materials, architecture and processing techniques. The lack of a standard strategy has hampered the progress of the field for a long time. Only recently, as the understanding of the rather complex physical processes at the metal/semiconductor interfaces has improved, more general approaches, with a validity that extends to several materials, are being proposed and successfully tested in the literature. Only a combined scientific and technological effort, on the one side to fully understand contact phenomena and on the other to completely master the tailoring of interfaces, will enable the development of advanced organic electronics applications and their widespread adoption in low-cost, large-area printed circuits.

Charge injection in solution-processed organic field-effect transistors: physics, models and characterization methods.

A variety of perylenetetracarboxy-3,4:9,10-diimide derivatives have been synthesized. Particular attention was paid to substituents in positions 1, 6, 7 or 12. The energy differences between the frontier orbitals have been determined using optical spectroscopy (UV and fluorescence). The energy of the lowest unoccupied orbitals (LUMOs) were obtained by cyclic voltammetry. From both studies, the energies of the highest occupied orbitals (HOMOs) were also been calculated. A Hammett-type relationship was observed for the reduction potentials (Ered11/2) when correlated with the σ−ortho parameter. The energies of the frontier orbitals define the domains of application of these compounds. They significantly depend on the substitution in positions 1, 6, 7, or 12.

Synthesis and characterization of 1,7-disubstituted and 1,6,7,12-tetrasubstituted perylenetetracarboxy-3,4:9,10-diimide derivatives

A waveguide AlInAs/AlGaInAs superlattice avalanche photodiode with a record 3 dB bandwidth of >20 GHz is reported at a wavelength of 1.55 /spl mu/m. A large gain-bandwidth product of >160 GHz is obtained. These devices are suitable for 20 Gbit/s long wavelength photoreceivers.

Waveguide AlInAs/GaAlInAs avalanche photodiode with a gain-bandwidth product over 160 GHz

The design, fabrication, and performance of double-stage taper photodiodes (DSTPs) are reported. The objective of this work is to develop devices compatible with 40-Gb/s applications. Such devices require high efficiency, ultrawide band, high optical power handling capability, and compatibility with low-cost module fabrication. The integration of mode size converters improves both the coupling efficiency and the responsivity with a large fiber mode diameter. Responsivity of 0.6 A/W and 0.45 A/W are achieved with a 6-/spl mu/m fiber mode diameter and cleaved fiber, respectively, providing relaxed alignment tolerances (/spl plusmn/1.6 /spl mu/m and /spl plusmn/2 /spl mu/m, respectively), compatible with cost-effective packaging techniques. DSTPs also offer a wide bandwidth greater than 40 GHz and transverse-electric/transverse-magnetic polarization dependence lower than 0.2 dB. Furthermore, a DSTP saturation current as high as 11 mA results in optical power handling greater than +10 dBm and a high output voltage of 0.8 V. These capabilities allow the photodiode to drive the decision circuit without the need of a broad-band electrical amplifier. The DSTP devices presented here demonstrate higher responsivities with large fiber mode diameter and better optical power handling capabilities and are compared with classical side-illuminated photodiodes.

Evanescently coupled photodiodes integrating a double-stage taper for 40-Gb/s applications-compared performance with side-illuminated photodiodes

A semiconductor opto-electronic device including at least one electronic function component (62), at least one optical function component (60) and a mode transformer associated with the optical function component. At least some layers of semiconductor material constituting the electronic function component also form optical layers in the mode transformer zone and, at least in the mode transformer zone, these semiconductor material layers are non-absorbent at the operating wavelength. The mode transformer is preferably etched in the shape of an hourglass.

Opto-electronic semiconductor device including an integrated mode transformer

We describe the design, optimization and fabrication of side-illuminated p-i-n photodetectors, grown on InP substrate, suitable for surface hybrid integration in low-cost modules. The targeted functionalities of these photodetectors were a very high responsivity at 1.3- and 1.55-/spl mu/m wavelengths and quasi-independent on the optical polarization, and had a high alignment tolerance. Moreover, in order to avoid any reliability problem, the principle of evanescent coupling was adopted. Two photodetectors were optimized, fabricated, and tested; the first was for classical cleaved fiber, and the second was for lensed fiber. Because the considered epitaxial structures were complicated to optimize, the method of the genetic algorithm was used, associated with a beam propagation method (BPM). The photodetectors are based on multimode diluted waveguides, which are promising structures in the field of optoelectronics and integrated optics. Starting from the presented comparisons between experimental and theoretical results, the interest of the design method is discussed and the complete performances of newly fabricated devices are presented. The aspect of the cutoff frequency is also considered.

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Design, optimization, and fabrication of side-illuminated p-i-n photodetectors with high responsivity and high alignment tolerance for 1.3and 1.55-/spl mu/m wavelength use

Louis Giraudet

Papers

Synthesis and characterization of 1,7-disubstituted and 1,6,7,12-tetrasubstituted perylenetetracarboxy-3,4:9,10-diimide derivatives

Waveguide AlInAs/GaAlInAs avalanche photodiode with a gain-bandwidth product over 160 GHz

Evanescently coupled photodiodes integrating a double-stage taper for 40-Gb/s applications-compared performance with side-illuminated photodiodes

Opto-electronic semiconductor device including an integrated mode transformer

Design, optimization, and fabrication of side-illuminated p-i-n photodetectors with high responsivity and high alignment tolerance for 1.3and 1.55-/spl mu/m wavelength use