The different exfoliation routes of graphite to produce graphene by sonication in solvent, chemical oxidation and electrochemical oxidation are compared. The exfoliation process and roughening of a flat graphite substrate is directly visualized at the nanoscale by scanning probe and electron microscopy. The etching damage in graphite and the properties of the exfoliated sheets are compared by Raman spectroscopy and X‐ray diffraction analysis. The results show the trade‐off between exfoliation speed and preservation of graphene quality. A key step to achieve efficient exfoliation is to couple gas production and mechanical exfoliation on a macroscale with non‐covalent exfoliation and preservation of graphene properties on a molecular scale.

New low-gap thiophene-based regular copolymers are produced by anodic coupling of 3,4ethylenedioxythiophene-2,5-substituted thieno [3,4-b]pyrazine (TP), cyclopenta[2,1-b;3,4-b′]dithiophen-4-one (CO), and 4-dicyanomethylene-4H-cyclopenta [2,1-b;3,4-b′]dithiophene (CN). The copolymers are characterized by cyclic voltammetry, FTIR reflection-absorption and UV-vis spectroscopy, electrochemical quartz crystal microbalance analysis, and in situ pand n-conductivity measurement. The copolymers show low optical gaps (measured at the maximum absorption) and electrochemical gaps (measured from redox potentials) in the range 0.8-1.3 eV. The CN-based polymer displays the lowest reported electrochemical gap (0.8 V). Random copolymers of CO and 3,4-ethylenedioxythiophene (EDT) have also been produced and compared with the relevant regular copolymer. Copolymerization of CO with increasing amounts of EDT decreases the gap. From an analysis of redox potential as a function of EDT fraction, it is found that the gap is limited by the redox potentials of the individual homopolymers. Localization of n-doping carriers in the polythiophene chains is progressively increased by donor-acceptor alternation and then by copolymerization till the expected intrinsic conductivity is made completely p-type.

Functional supramolecular architectures for bottom-up organic nano- and microtechnology are a high priority research topic. We discovered a new recognition algorithm, resulting from the combination of thioalkyl substituents and head-to-head regiochemistry of substitution, to induce the spontaneous self-assembly of sulfur overrich octathiophenes into supramolecular crystalline fibers combining high charge mobility and intense fluorescence. The fibers were grown on various types of surfaces either as superhelices or straight rods depending on molecular structure. Helical fibers directly grown on a field effect transistor displayed efficient charge mobility and intrinsic 'memory effect'. Despite the fact that the oligomers did not have chirality centers, one type of hand-helicity was always predominant in helical fibers, due to the interplay of molecular atropisomerism and supramolecular helicity induced by terminal substituents. Finally, we found that the new sulfur overrich oligothiophenes can easily be prepared in high yields through ultrasound and microwave assistance in green conditions.

Several types of lithium ion conducting polymer electrolytes have been synthesized by hot-pressing homogeneous mixtures of the components, namely, poly(ethylene oxide) (PEO) as the polymer matrix, lithium trifluoromethane su.lfonate (LiCF3SO3), and lithium tetrafluoborate (LiBF4), respectively, as the lithium salt, and lithium gamma-aluminate -y-LiA1O2, as a ceramic filler. This preparation procedure avoids any step including liquids so that plasticizer-free, composite polymer electrolytes can be obtained. These electrolyte have enhanced electrochemical properties, such as an ionic conductivity of the order of i0 S cm' at 80-90°C and an anodic breakdown voltage higher than 4 V vs. Li. In addition, and most importantly, the combination of the dry feature of the synthesis procedure with the dispersion of the ceramic powder, concurs to provide these composite electrolytes with an exceptionally high stability with the lithium metal electrode. In fact, this electrode cycles in these dry polymer electrolytes with a very high efficiency, i.e., approaching 99%. This in turn suggests the suitability of the electrolytes for the fabrication of improved rechargeable lithium polymer batteries.

The design, synthesis and structure-property investigation of a new thienopyrrolyl dione substituted oligothiophene material showing reduced band gap energy, low lying LUMO energy level and ambipolar semiconducting behaviour is described.

Supercapacitors are battery-complementary devices for applications demanding high operating power levels. [1][2][3] The increasing interest in such devices is stimulated by the prospect of their use as secondary power sources in electric vehicles (EVs) to provide peak power for acceleration and hill climbing. For EV supercapacitors, the U.S. Department of Energy (DOE) has set the following goals for specific power and energy of a fully packaged device: 500 W kg Ϫ1 and 5 Wh kg Ϫ1 (near-term goals, 1998-2003) and 1500 W kg Ϫ1 and 15 Wh kg Ϫ1 (advanced goals) 4 with a device cycle-life of 10 5 cycles. 1 Two types of supercapacitors are under development: the doublelayer and the redox supercapacitors. In the former, energy storage arises mainly from the separation of electronic and ionic charges at the interface between high-specific-area electrode materials and electrolyte solution, i.e., it is electrostatic in origin. 5 In the latter, fast faradaic reactions take place at the electrode materials at characteristic potentials, as in batteries, and give rise to what is called pseudocapacitance. 6 The targets are the same for both device types: the development of electrode materials with high specific capacitance, for maximizing specific energy, and with low electric resistance, for maximizing specific power, and of high stability to repeated chargedischarge cycles for a long cycle life. Additional requisites include electrolytes with high breakdown potential for greater energy storage and low resistivity for greater power, and for market success, materials with a high performance-to-cost ratio.Electrode materials for double-layer supercapacitors are essentially activated carbon of high specific area up to 2500 m 2 g Ϫ1 ; high performance C/C supercapacitors are already on the market. 1,7 For redox supercapacitors, two classes of electrode materials are being developed: the noble metal oxides for use in aqueous electrolytes, with ruthenium oxide as the best performing, 8 and electronically conducting polymers (ECPs) for use in both aqueous 9 and organic electrolytes. 10 The latter class is the most promising for EV supercapacitors, particularly because it enables devices to work at potentials as high as from 3.0 to 3.2 V, and also because of the lower cost of ECPs with respect to RuO 2 .The faradaic reactions occurring in ECPs are the p-doping and ndoping processes (Scheme 1 with polythiophene as an example).

A facile and efficient method based on electrochemistry for the production of graphene‐based materials for electronics is demonstrated. Uncharged acetonitrile molecules are intercalated in graphite by electrochemical treatment, owing to the synergic action of perchlorate ions dissolved in acetonitrile. Then, acetonitrile molecules are decomposed with microwave irradiation, which causes gas production and rapid graphite exfoliation, with an increase in the graphite volume of up to 600 %. Upon further processing and purification, highly dispersible nanosheets are obtained that can be processed into thin layers by roll‐to‐roll transfer or into thicker electrodes with excellent capacitance stability upon extensive charging/discharging cycles. The good exfoliation yield (>50 % of monolayers), minimal oxidation damage and good electrochemical stability of the nanosheets obtained were confirmed by scanning force and electron microscopy, as well as Raman spectroscopy and galvanostatic analyses.

Organic molecular semiconductors are key components for a new generation of low cost, flexible, and large area electronic devices. In particular, ambipolar semiconductors endowed with electroluminescent properties have the potential to enable a photonic field-effect technology platform, whose key building blocks are the emerging organic light-emitting transistor (OLET) devices. To this aim, the design of innovative molecular configurations combining effective electrical and optical properties in the solid state is highly desirable. Here, we investigate the effect of the insertion of a thieno(bis)imide (TBI) moiety as end group in highly performing unipolar oligothiophene semiconductors on the packing, electrical, and optoelectronic properties of the resulting materials. We show that, regardless of the HOMO–LUMO energy, orbital distribution, and molecular packing pattern, a TBI end moiety switches unipolar and nonemissive oligothiophene semiconductors to ambipolar and electroluminescent materials. Remarkably, the newly developed materials enabled the fabrication of single layer molecular ambipolar OLETs with optical power comparable to that of the equivalent polymeric single layer devices.