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

https://pure.rug.nl/ws/files/6752508/2010OrganometallicsPonomarenkoSupp.pdf

Synthesis of monochlorosilyl derivatives of dialkyloligothiophenes for self-assembling monolayer field-effect transistors

Fullerene-containing macromolecules for materials science applications

Field-effect transistor comprising a gate electrode layer, a first dielectric layer, a source electrode, a drain electrode, an organic semiconductor and a second dielectric layer, wherein the first dielectric layer is located on the gate electrode layer, the source electrode, the drain electrode and the organic semiconductor are located above the first dielectric layer, the source electrode and the drain electrode are in contact with the organic semiconductor, wherein the second dielectric layer is placed upon the assembly of source electrode, drain electrode and organic semiconductor and wherein during operation of the field-effect transistor the capacitance of the assembly comprising the gate electrode layer and the first dielectric layer is lower than the capacitance of the second dielectric layer. Further a sensor system comprising such a field-effect transistor and the use of a sensor system for detecting molecules is disclosed.

Organic field-effect transistor for sensing applications

An iron (1), comprising: - a water reservoir (16), configured to hold liquid water; - a heatable soleplate (20); - at least one water outlet opening (24); - a water atomization and distribution unit (30), configured to atomize water from the water reservoir and to distribute the atomized water to the at least one water outlet opening; - at least one sensor (40,42), configured to monitor at least one motion dependent variable of the iron and to generate a reference signal reflecting said variable; - a control unit (50), operatively connected to both the water atomization and distribution unit (30) and the at least one sensor (40, 42), and configured to control a water outflow rate of the at least one water outlet opening (24) by controlling the operation of the water atomization and distribution unit in dependence of the reference signal generated by the at least one sensor.

Iron featuring liquid phase garment moisturization via soleplate

Photovoltaic cells have been prepared with blends of a polymerizable methanofullerene derivative bearing four butadiyne subunits and MDMO-PPV; annealing at 100 °C for 2 hours resulted in an improvement of the performances of the devices and AFM studies suggested that cross-linking polymerization of the fullerene derivative is capable of stabilizing the initially formed phases.

Sepas Setayesh

Papers

Synthesis of monochlorosilyl derivatives of dialkyloligothiophenes for self-assembling monolayer field-effect transistors

Fullerene-containing macromolecules for materials science applications

Organic field-effect transistor for sensing applications

Iron featuring liquid phase garment moisturization via soleplate

Towards polymerizable fullerene derivatives to stabilize the initially formed phases in bulk-heterojunction solar cells