Thiophene ring is a class of oxygen heterocyclic compounds containing sulfur element. Compared with the benzene ring, the thiophene ring has a larger electron cloud density (due to the presence of sulfur atoms), which is more favorable for hole injection. Organic semiconductor materials composed of thiophene as a structural unit are widely used. The benzothiophene derivatives can be obtained by conjugating a benzene ring with a thiophene ring, which are a class of fused ring compounds containing sulfur, a plane, and an extended π system. Such compounds have the following advantages: (1) Purification by means of extraction, adsorption and recrystallization can obtain high-purity materials; (2) The molecular planarity is regular, and the prepared electronic device has high carrier mobility; (3) It is easy to form a self-assembled polycrystalline film, with few lattice defects and a potential barrier for carrier migration, which can improve the field effect mobility of the device. These advantages make semiconductor materials prepared from such compounds widely used in field-effect transistors and thin-film devices.
Figure 1. Chemical structure of benzothiophene
- Organic Field Effect Transistor (OFET): Good π-π conjugation and efficient molecular packing properties resulting from strong intermolecular forces are necessary conditions for high mobility of OFETs. Substituting some carbon atoms of fused ring molecules with heteroatoms can make the material have more excellent field effect performance and stability. At room temperature, the benzothiophene derivatives obtained by introducing a thiophene ring into the benzene ring system exhibited good field-effect performance and stability, resulting in the fabricated OFETs with high mobility and high stability. Thin film field effect transistors need to use highly conjugated materials with good crystalline properties to improve the migration efficiency. Benzothiophene has good solubility, can form polycrystalline films, and can be prepared into thin-film semiconductor materials. Continuing to expand the π system in structure, such as thiophene and acene, can further improve the mobility and oxidative stability of the device.
- Chao He,Yaowu He,Xuncheng Liu,Aiyuan Li,Junwu Chen,Hong Meng. Enhancing the performance of solution-processed organic thin-film transistors by blending binary compatible small molecule semiconductors [J]. Org. Electron., 2018, 64, 104-109.