Organic semiconductor

About: Organic semiconductor is a research topic. Over the lifetime, 15905 publications have been published within this topic receiving 533881 citations.

Fabrication of surface-supported low-dimensional polyimide networks.

Abstract: Interest in thermal and chemical stability of surface-supported organic networks has stimulated recent attempts to covalently interlink adsorbed molecular species into extended nanostructures. We show, using low-temperature scanning tunneling microscopy, that imidization of anhydrides and amines adsorbed on Au(111) can be thermally initiated under controlled ultrahigh vacuum conditions. Using two types of amine-functionalized polyphenyl molecules together with the organic semiconductor PTCDA, monolayer thick linear polymeric strands and a porous polymeric network with nanoscale dimensions are obtained.

Improved morphology and charge carrier injection in pentacene field-effect transistors with thiol-treated electrodes

Abstract: The influence of chemical surface modifications of gold electrodes on the morphology and the electrical properties has been studied for pentacene based thin-film transistors with channel lengths of L⩽4μm. Self-assembled monolayers (SAMs) of various aliphatic and aromatic organothiols have been used to selectively modify the metallic source and drain electrodes and are further compared with reference samples with untreated electrodes. For all SAM-treated devices a reduced roughness of the pentacene film is observed which is accompanied by a reduction of the threshold voltage from about VT=2V for untreated transistors to −0.9V for transistors with SAM modified electrodes. Using aliphatic SAMs a poor on/off ratio of about 102 was obtained which is attributed to their low conductivity. In contrast, the on/off ratio is enhanced by four orders of magnitude if the surface is modified by an aromatic SAM. In this case a subthreshold swing as low as 0.55V/decade is achieved which corresponds to a trap density reduc...

Bulky end-capped [1]benzothieno[3,2-b]benzothiophenes: reaching high-mobility organic semiconductors by fine tuning of the crystalline solid-state order.

Abstract: A series of bulky end-capped [1]benzothieno[3,2-b]benzothiophenes (BTBTs) are developed in order to tune the packing structure via terminal substitution. A coupled theoretical and experimental study allows us to identify 2,7-di-tert-butylBTBT as a new high-performance organic semiconductor with large and well-balanced transfer integrals, as evidenced by quantum-chemical calculations. Single-crystal field-effect transistors show a remarkable average saturation mobility of 7.1 cm(2) V(-1) s(-1) .

Organic solar cells of hydroxy squarylium

Abstract: The photovoltaic properties of Schottky barrier solar cells made from thin films (100–1000 A) of the organic dye hydroxy squarylium have been studied. Amorphous and polycrystalline films, prepared by evaporation and solution casting, have strong absorption over the entire visible spectrum. The highest power conversion efficiency measured under AMO white light was 0.1% (0.14 mW/cm2 input intensity); this decreased to 0.02% at 135 mW/cm2. The decrease in η with intensity is characteristic of organic materials, but is usually much more pronounced. For 8500‐A monochromatic light the quantum efficiency was as high as 2.3% and the conversion efficiency was 0.2% (1 mW/cm2).

Electronic traps in organic transport layers

Abstract: The knowledge about properties of electronic traps in organic semiconductors is one of the major keys for the understanding and optimization of charge transport in organic devices. In the present article the density of occupied states of the most prominent pristine small molecule systems and selected polymers are reported determined, by fractional thermally stimulated current and luminescence techniques. In order to distinguish between impurity and structurally based traps, model systems of doped as well as differently deposited layers were studied. In addition, the influence of detected traps on steady state I–V and dynamic time-of-flight characteristics are reported. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)