http://www.mdpi.com/journal/materials/special_issues/org-electr-mat/ Dear Colleagues, Since the discovery of conducting polymers more than forty years ago, organic electronic materials are making their way to everyday\'s life, promising tunable, cheap and flexible materials for displays, lighting, solar panels and microchips. To improve the performance in these devices, several processes have to be optimized, i.e optical absorption, exciton diffusion, charge generation, recombination and transport. These processes are governed by the electronic nature of the film-constituting molecules as well as by their mutual arrangement, which in turn is controlled by the intra-molecular geometrical and electronic properties. A full understanding of these processes to exploit the richness of organic synthesis thus demands intense collaboration of material science, theory, spectroscopy, device physics and engineering. To reflect the latest developments in the field, we feature a special issue on "Organic Electronic Materials", covering different aspects like synthesis, characterization, processes and devices. Johannes Gierschner, Ph. D. Guest Editor Submission All papers should be submitted to materials@mdpi.com. To be published continuously until the deadline and papers will be listed together at the special website. Submitted papers should not have been published previously, nor be under consideration for publication elsewhere. All papers are refereed through a peer-review process. A guide for authors is available on the Instructions for Authors page. Materials is an international peer-reviewed quarterly journal published by MDPI. Review manuscripts: Before writing their manuscripts, potential authors of review articles should forward the title and a short abstract to materials@mdpi.com. We will then provide feedback on the suitability of the topic. Open Access publication fees are 300 CHF per paper. English correction fees and/or formatting fees (250 CHF) will be added in certain cases (550 CHF per paper for those papers that require extensive additional formatting and/or English corrections). Starting 1 January 2010, Article Processing Charges are of 800 CHF per accepted article for Materials http://www.mdpi.com/1996-1944/3/8/4214/ Our goal in this review is three-fold. First, we provide an overview of a number of quantum-chemical methods that can abstract charge-transfer (CT) information on the excited-state species of organic conjugated materials, which can then be exploited for the understanding and design of organic photodiodes and solar cells at the molecular level. We stress that the Composite-Molecule (CM) model is useful for evaluating the electronic excited states and excitonic couplings of the organic molecules in the solid state. We start from a simple polyene dimer as an example to illustrate how interchain separation and chain size affect the intercahin interaction and the role of the charge transfer interaction in the excited state of the polyene dimers. With the basic knowledge from analysis of the polyene system, we then study more practical organic materials such as oligophenylenevinylenes (OPVn), oligothiophenes (OTn), and oligophenylenes (OPn). Finally, we apply this method to address the delocalization pathway (through-bond and/or through-space) in the lowest excited state for cyclophanes by combining the charge-transfer contributions calculated on the cyclophanes and the corresponding hypothetical molecules with tethers removed. This review represents a step forward in the understanding of the nature of the charge-transfer interactions in the excited state of organic functional materials. http://www.mdpi.com/1996-1944/3/8/4214/ Thu, 05 Aug 2010 00:00:00 CEST Materials 2010-08-05 3 8 Review 4214 4251 1996-1944 Charge-Transfer Interactions in Organic Functional Materials 2010-08-05 doi: 10.3390/ma3084214 Hsin-Chieh Lin Bih-Yaw Jin http://www.mdpi.com/1996-1944/3/5/3077/ This review is an overview of our previous work on the synthesis and properties of poly(p-phenylenevinylene)s (PPVs) selectively fluorinated in different positions of the conjugated backbone. Both the synthetic challenges and the effects of functionalization with fluorine atoms on the optical behavior are discussed, highlighting the peculiarities and the interest of this class of conjugated polymers. A general polymerization protocol for PPVs, that is based on the Pd-catalyzed Stille cross-coupling reaction of bis-stannylated vinylene monomers with aromatic bis-halides, has been successfully extended to the synthesis of selectively fluorinated poly(p-phenylenevinylene)s. The properties of a series of these PPVs differing in the number and positions of the fluorine atoms on the conjugated backbone have been studied, even in comparison with the non-fluorinated counterparts. The intriguing optical features of the resulting materials are discussed considering not only the role of the electronic and steric effects induced by the fluorine substituents, but also the impact of the fluorination on the solid state organization and intermolecular interactions. http://www.mdpi.com/1996-1944/3/5/3077/ Fri, 07 May 2010 00:00:00 CEST Materials 2010-05-07 3 5 Review 3077 3091 1996-1944 Fluorinated Poly(p-phenylenevinylene)s: Synthesis and Optical Properties of an Intriguing Class of Luminescent Polymers 2010-05-07 doi: 10.3390/ma3053077 Farinola Cardone Babudri Martinelli Naso Bruno Losurdo http://www.mdpi.com/1996-1944/3/4/2668/ A computational study was carried out to examine the electronic and optical properties of the experimentally proposed ferrocene-based molecular diode that used 2,5-diethynylpyridine as a bridging unit. Density functional theory, time-dependent density functional theory, and constrained density functional theory were applied to investigate various aspects of the underlying electron transfer mechanism. The results not only advance our understanding of the experimental observations, but also demonstrate the usefulness of computational approaches for the design of new electronic materials. http://www.mdpi.com/1996-1944/3/4/2668/ Tue, 13 Apr 2010 00:00:00 CEST Materials 2010-04-13 3 4 Article 2668 2683 1996-1944 Computational Study of Ferrocene-Based Molecular Frameworks with 2,5-Diethynylpyridine as a Chemical Bridge 2010-04-13 doi: 10.3390/ma3042668 Ding Chen Wang http://www.mdpi.com/1996-1944/3/3/2027/ The charge ordered organic salt θ-(BEDT-TTF)2CsZn(SCN)4 exhibits a giant nonlinear conduction at low temperatures. The voltage-current characteristics of this compound are similar to those of a thyristor device, after which we named it the organic thyristor. This material shows current oscillation in the presense of dc voltage, which arises from a mechanism different from conventional oscillating circuits, because the oscillation appears in a sample that does not show negative derivative resistance. We have performed a standard circuit analysis, and show that the voltage-current curve is “blurred” in the high current region, and the oscillation occurs in the blurred region. This type of oscillation has never been reported, and a possible origin for this is suggested. http://www.mdpi.com/1996-1944/3/3/2027/ Fri, 19 Mar 2010 00:00:00 CET Materials 2010-03-19 3 3 Article 2027 2036 1996-1944 A Mechanism of DC-AC Conversion in the Organic Thyristor 2010-03-19 doi: 10.3390/ma3032027 Suko Terasaki Mori Mori http://www.mdpi.com/1996-1944/3/3/1640/ A lot of molecular (magnetic) conductors are prepared largely using charge-transfer (CT) salts of donor molecules with acceptor molecules or nonmagnetic or magnetic anions such as metal halides and oxides; their CT salts are usually obtained as bulk crystals, which are used to elucidate the electrical conducting (magnetic) properties. In contrast, a small number of micro/nano-crystals of the molecular (magnetic) conductors, especially micro/nano-wires, are known, of which highly conducting nanowires are necessary as a key component in the development of the next generation of nano-size transistors and spin-transistors. Very recently, we succeeded in preparing highly conductive micro/nano-wires of CT salts between bent donor molecules developed by one of the author’s group and magnetic FeX4– (X = Cl, Br) ions: (1) by electrochemical oxidation of the bent donor molecules with a silicon wafer electrode coated with a phospholipid multi-lamellar structure as well as, (ii) by electrochemical oxidation of the bent donor molecules with a large arc structure, in the presence of NBu4FeX4 supporting electrolytes. This article reviews template-free and template-assisted methods developed so far for the preparation of micro/nano-wires of molecular (magnetic) conductors along with our new methods. The conducting properties of these micro/nano-wires are compared with those of the corresponding bulk crystals. http://www.mdpi.com/1996-1944/3/3/1640/ Mon, 08 Mar 2010 00:00:00 CET Materials 2010-03-08 3 3 Review 1640 1673 1996-1944 New Development in the Preparation of Micro/Nano-Wires of Molecular (Magnetic) Conductors 2010-03-08 doi: 10.3390/ma3031640 Toyonari Sugimoto Hisashi Tanaka Dominique De Caro Lydie Valade http://www.mdpi.com/1996-1944/3/3/1533/ In the organic electronics research field, several strategies have been used to modulate the transport properties of thiophene-derived semiconductors via sequential functionalization of their π-conjugated cores. This review summarizes the major design and synthetic strategies for tuning thiophene-containing small molecule and polymer properties by introducing electron-deficient nitrogen-containing azine and azole moieties. Several examples are presented which elucidate the structural, optical, and electronic consequences of incorporating these electron-deficient fragments in the conjugated skeletons, particularly relating to applications in organic thin-film transistors. http://www.mdpi.com/1996-1944/3/3/1533/ Wed, 03 Mar 2010 00:00:00 CET Materials 2010-03-03 3 3 Review 1533 1558 1996-1944 Azine- and Azole-Functionalized Oligo´ and Polythiophene Semiconductors for Organic Thin-Film Transistors 2010-03-03 doi: 10.3390/ma3031533 Rocío Ponce Ortiz He Yan Antonio Facchetti Tobin J. Marks