Pentacene

Pentacene is a polycyclic aromatic hydrocarbon consisting of five linearly fused benzene rings (chemical formula C22H14). It is the simplest of the longer acenes and is extensively studied as a model organic semiconductor.

Physically, pentacene is a crystalline solid that is insoluble in water and has limited solubility in common organic solvents. It is typically deposited as a thin film by thermal evaporation in high vacuum, yielding highly ordered, anisotropic crystals. The molecule is planar and highly conjugated, which supports dense pi-electron packing in the solid state.

Electronic properties: Pentacene is a p-type organic semiconductor with relatively high charge-carrier mobility in well-ordered films and single crystals. In optimized devices, field-effect mobilities can exceed 1 cm^2/Vs, making pentacene one of the best-performing organic semiconductors to date. It relies on efficient intermolecular interactions in the solid state to transport charges.

Stability and handling: Pentacene is sensitive to air and light; it readily oxidizes to pentacenequinone, and device performance degrades upon prolonged exposure to oxygen or UV light. For practical use, devices based on pentacene are typically encapsulated to limit exposure.

Derivatives and processing: To improve solubility and processability, various derivatives have been developed, notably bulky alkylsilylethynyl substituents such as 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene). These derivatives enable solution processing and printable electronics, while retaining high mobility in thin films and transistors.