Fossil fuel alternatives, such as solar energy, are moving to the forefront in a variety of research fields. Polymer-based organic photovoltaic systems hold the promise for a cost-effective, lightweight solar energy conversion platform, which could benefit from simple solution processing of the active layer. The function of such excitonic solar cells is based on photoinduced electron transfer from a donor to an acceptor. Fullerenes have become the ubiquitous acceptors because of their high electron affinity and ability to transport charge effectively. The most effective solar cells have been made from bicontinuous polymer–fullerene composites, or so-called bulk heterojunctions. The best solar cells currently achieve an efficiency of about 5 %, thus significant advances in the fundamental understanding of the complex interplay between the active layer morphology and electronic properties are required if this technology is to find viable application.

Polymer–Fullerene Composite Solar Cells

2.2. Materials 929 2.3. Factors Influencing Charge Mobility 931 2.3.1. Molecular Packing 931 2.3.2. Disorder 932 2.3.3. Temperature 933 2.3.4. Electric Field 934 2.3.5. Impurities 934 2.3.6. Pressure 934 2.3.7. Charge-Carrier Density 934 2.3.8. Size/molecular Weight 935 3. The Charge-Transport Parameters 935 3.1. Electronic Coupling 936 3.1.1. The Energy-Splitting-in-Dimer Method 936 3.1.2. The Orthogonality Issue 937 3.1.3. Impact of the Site Energy 937 3.1.4. Electronic Coupling in Oligoacene Derivatives 938

Charge transport in organic semiconductors.

Since the discovery of highly conducting polyacetylene by Shirakawa, MacDiarmid, and Heeger in 1977, π-conjugated systems have attracted much attention as futuristic materials for the development and production of the next generation of electronics, that is, organic electronics. Conceptually, organic electronics are quite different from conventional inorganic solid state electronics because the structural versatility of organic semiconductors allows for the incorporation of functionality by molecular design. This versatility leads to a new era in the design of electronic devices. To date, the great number of π-conjugated semiconducting materials that have either been discovered or synthesized generate an exciting library of π-conjugated systems for use in organic electronics. 11 However, some key challenges for further advancement remain: the low mobility and stability of organic semiconductors, the lack of knowledge regarding structure property relationships for understanding the fundamental chemical aspects behind the structural design, and realization of desired properties. Organic field-effect transistors (OFETs) are a kind of device consisting of an organic semiconducting layer, a gate insulator layer, and three terminals (drain, source, and gate electrodes). OFETs are not only essential building blocks for the next generation of cheap and flexible organic circuits, but they also provide an important insight into the charge transport of πconjugated systems. Therefore, they act as strong tools for the exploration of the structure property relationships of πconjugated systems, such as parameters of field-effect mobility (μ, the drift velocity of carriers under unit electric field), current on/off ratio (the ratio of the maximum on-state current to the minimum off-state current), and threshold voltage (the minimum gate voltage that is required to turn on the transistor). 17 Since the discovery of OFETs in the 1980s, they have attracted much attention. Research onOFETs includes the discovery, design, and synthesis of π-conjugated systems for OFETs, device optimization, development of applications in radio frequency identification (RFID) tags, flexible displays, electronic papers, sensors, and so forth. It is beyond the scope of this review to cover all aspects of π-conjugated systems; hence, our focus will be on the performance analysis of π-conjugated systems in OFETs. This should make it possible to extract information regarding the fundamental merit of semiconducting π-conjugated materials and capture what is needed for newmaterials and what is the synthesis orientation of newπ-conjugated systems. In fact, for a new science with many practical applications, the field of organic electronics is progressing extremely rapidly. For example, using “organic field effect transistor” or “organic field effect transistors” as the query keywords to search the Web of Science citation database, it is possible to show the distribution of papers over recent years as shown in Figure 1A. It is very clear

Semiconducting π-conjugated systems in field-effect transistors: a material odyssey of organic electronics.

Functionalized acenes and heteroacenes for organic electronics.

Organic semiconductors have been the subject of active research for over a decade now, with applications emerging in light-emitting displays and printable electronic circuits. One characteristic feature of these materials is the strong trapping of electrons but not holes1: organic field-effect transistors (FETs) typically show p-type, but not n-type, conduction even with the appropriate low-work-function electrodes, except for a few special high-electron-affinity2,3,4 or low-bandgap5 organic semiconductors. Here we demonstrate that the use of an appropriate hydroxyl-free gate dielectric—such as a divinyltetramethylsiloxane-bis(benzocyclobutene) derivative (BCB; ref. 6)—can yield n-channel FET conduction in most conjugated polymers. The FET electron mobilities thus obtained reveal that electrons are considerably more mobile in these materials than previously thought. Electron mobilities of the order of 10-3 to 10-2 cm2 V-1 s-1 have been measured in a number of polyfluorene copolymers and in a dialkyl-substituted poly(p-phenylenevinylene), all in the unaligned state. We further show that the reason why n-type behaviour has previously been so elusive is the trapping of electrons at the semiconductor–dielectric interface by hydroxyl groups, present in the form of silanols in the case of the commonly used SiO2 dielectric. These findings should therefore open up new opportunities for organic complementary metal-oxide semiconductor (CMOS) circuits, in which both p-type and n-type behaviours are harnessed.

General observation of n-type field-effect behaviour in organic semiconductors

This invention relates to a device (100) to be worn by or attached to an animal (102) for indicating the physiological status of the animal. At least one measuring device is used for measuring the physiological state of said animal . The resulting physiological data are regularly compared to at least one threshold value when evaluating the current physiological status of said animal. Based thereon, indication means indicates the current physiological status of said animal.

A device to be attached to or to be worn by an animal for indicating the physiological status of the animal

An electronic device comprising a heterojunction, wherein the heterojunction comprises a blend comprising an electron donor and an electron acceptor; and wherein the blend is treated so as to form one or more linkages between the electron donor and/or electron acceptor in the treated blend.

Heterojunction with linkages between an electron donor and an electron acceptor in a blend

The present invention provides a method of forming a semiconducting device comprising an organic semiconducting material, which method comprises: heating a composition comprising the organic semiconducting material to a temperature at or above the melting point or glass transition temperature of the composition to form a melt; cooling the melt to a temperature below the melting point or glass transition temperature of the composition; and wherein a first substance or object capable of inhibiting and/or preventing dewetting is adjacent the composition before or during heating, or the composition further comprises an agent capable of inhibiting and/or preventing dewetting.

Composition and Method of Forming a Device

A device for performing an action on a surface comprises at least one movably arranged functional body (21, 22), driving means for driving the functional body (21, 22), main safety means for decoupling the driving means from the functional body (21, 22) when a load exerted by the functional body (21, 22) in the direction of the driving means under the influence of resistance forces experienced by the functional body (21, 22) exceeds a predetermined maximum value, and additional safety means (40) which are movably arranged in the vicinity of the functional body (21, 22), and which are capable of exerting loads on the main safety means to different extents in different positions, at a side of the main safety means associated with the functional body (21, 22). The additional safety means may comprise a bar (40) having a non-circular cross-sectional area, which is rotatable about its longitudinal axis (41).

Device Comprising a Movably Arranged Functional Body and a Safety Mechanism for Stopping Movement of the Functional Body

A composition for forming a semiconducting device includes an organic semiconducting material, an agent capable of inhibiting and/or preventing dewetting, and an additional substance, wherein the additional substance is provided in an amount capable of preventing initial crystallization of the composition and reducing the melting point or glass transition temperature of the composition below the melting point or glass transition temperature of the organic semiconducting material. The additional substance may be naphthalene, phenylnaphthalene, anthrance, or diphenylanthrance.

Sepas Setayesh

Papers

A device to be attached to or to be worn by an animal for indicating the physiological status of the animal

Heterojunction with linkages between an electron donor and an electron acceptor in a blend

Composition and Method of Forming a Device

Device Comprising a Movably Arranged Functional Body and a Safety Mechanism for Stopping Movement of the Functional Body

Composition for forming an organic semiconducting device