An organic semiconductor is an organic material

Organic chemistry

Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, composition, reactions, and preparation of carbon-based compounds, hydrocarbons, and their derivatives...

 with semiconductor

Semiconductor

A semiconductor is a material with electrical conductivity due to electron flow intermediate in magnitude between that of a conductor and an insulator. This means a conductivity roughly in the range of 103 to 10−8 siemens per centimeter...

 properties. Single molecule

Molecule

A molecule is an electrically neutral group of at least two atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their electrical charge...

s, short chain (oligomer

Oligomer

In chemistry, an oligomer is a molecule that consists of a few monomer units , in contrast to a polymer that, at least in principle, consists of an unlimited number of monomers. Dimers, trimers, and tetramers are oligomers. Many oils are oligomeric, such as liquid paraffin...

s) and organic polymer

Polymer

A polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...

s can be semiconductive. Semiconducting small molecules (aromatic hydrocarbons) include the polycyclic aromatic compounds pentacene

Pentacene

Pentacene is a polycyclic aromatic hydrocarbon consisting of five linearly-fused benzene rings. This highly conjugated compound is an organic semiconductor. The compound generates excitons upon absorption of ultra-violet or visible light; this makes it very sensitive to oxidation...

, anthracene

Anthracene

Anthracene is a solid polycyclic aromatic hydrocarbon consisting of three fused benzene rings. It is a component of coal-tar. Anthracene is used in the production of the red dye alizarin and other dyes...

, and rubrene

Rubrene

Rubrene is a red colored polycyclic aromatic hydrocarbon. Rubrene is used as a sensitiser in chemoluminescence and as a yellow light source in lightsticks....

. Polymeric organic semiconductors include poly(3-hexylthiophene), poly(p-phenylene vinylene)

Poly(p-phenylene vinylene)

Poly is a conducting polymer of the rigid-rod polymer host family.PPV is the only polymer of this type that has so far been successfully processed into a highly ordered crystalline thin film. PPV and its derivatives are conducting polymers of rigid-rod polymer family...

, as well as polyacetylene

Polyacetylene

Polyacetylene is an organic polymer with the repeat unit n. The high electrical conductivity discovered for these polymers beginning in the 1960's accelerated interest in the use of organic compounds in microelectronics...

 and its derivatives.

There are two major overlapping classes of organic semiconductors.