Phenacenes are a class of

organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...

s consisting of fused aromatic rings. They are

polycyclic aromatic hydrocarbon A Polycyclic aromatic hydrocarbon (PAH) is any member of a class of organic compounds that is composed of multiple fused aromatic rings. Most are produced by the incomplete combustion of organic matter— by engine exhaust fumes, tobacco, incine ...

s, related to

acene In organic chemistry, the acenes or polyacenes are a class of organic compounds and polycyclic aromatic hydrocarbons made up of benzene () rings which have been linearly fused. They follow the general molecular formula . The larger represent ...

s and

helicene In organic chemistry, helicenes are aromatic ortho substituent, ortho-condensed Polycyclic compound, polycyclic Aromaticity, aromatic compounds in which Benzene, benzene rings or other aromatics are angularly annulation, annulated to give helix, ...

s from which they differ by the arrangement of the fused rings.

Relevance to organic electronic materials

Aromatic compounds with extended π-conjugated system have attracted attention because of their potential use in

organic electronics Organic electronics is a field of materials science concerning the design, Chemical synthesis, synthesis, characterization, and application of Organic compound, organic molecules or polymers that show desirable Electronics, electronic properties ...

organic semiconductor Organic semiconductors are solids whose building blocks are pi-bonded molecules or polymers made up by carbon and hydrogen atoms and – at times – heteroatoms such as nitrogen, sulfur and oxygen. They exist in the form of molecular crystals o ...

s. Of academic interest, pentacene has been widely used as an active layer in organic thin-film field-effect transistors (

OFET An organic field-effect transistor (OFET) is a field-effect transistor using an organic semiconductor in its channel. OFETs can be prepared either by vacuum evaporation of small molecules, by solution-casting of polymers or small molecules, or ...

). The main drawback of pentacene OFET is degradation upon exposure to light and air. On the other hand, henacenes, an isomeric form of cenes, has been known as a stable compound in which the benzene rings are fused in a zigzag structure. For the past several years, there is renewed interest in synthesis of henacene derivatives associated with electronic applications in emissive and semi- or superconducting materials.

Picene Picene is a hydrocarbon found in the pitchy residue obtained in the distillation of peat tar and of petroleum. This is distilled to dryness and the distillate repeatedly recrystallized from cymene. It may be synthetically prepared by the action ...

( henacene) can serve as an active layer of a high-performance p-channel organic thin-film FET with very high

field-effect mobility In solid-state physics, the electron mobility characterizes how quickly an electron can move through a metal or semiconductor when pushed or pulled by an electric field. There is an analogous quantity for holes, called hole mobility. The term ca ...

μ = 5 cm²/(V⋅s). henacene FET shows μ = 0.75 cm²/(V⋅s) and no sensitivity to air. Furthermore, picene doped with potassium and rubidium exhibit

superconductivity Superconductivity is a set of physical properties observed in superconductors: materials where Electrical resistance and conductance, electrical resistance vanishes and Magnetic field, magnetic fields are expelled from the material. Unlike an ord ...

with a maximum critical temperature ''T''_C ≈ 18 K. Thus, henacenes and their derivatives may play an important role in future fabrication of stable and high-performance electronic devices such as OFET,

OLED An organic light-emitting diode (OLED), also known as organic electroluminescent (organic EL) diode, is a type of light-emitting diode (LED) in which the emissive electroluminescent layer is an organic compound film that emits light in respon ...

and

organic solar cells An organic solar cell (OSC) or plastic solar cell is a type of photovoltaic that uses organic electronics, a branch of electronics that deals with conductive organic polymers or small organic molecules, for light absorption and charge transport t ...

. Substituted picenes may serve as an active layer of OFETs.Nakano, Y.; Saito, M.; Nakamura, H. , 2010.

References

{{PAHs Polycyclic aromatic hydrocarbons