This category includes a range of compounds that do not fall into the above categories but are still important building blocks of small molecule semiconductors. These compounds may exhibit unique electronic, optical or thermal properties that make them suitable for specific applications in organic electronics. They can be synthesized with a variety of substituents and functional groups to tune their properties for use in OLEDs, OPVs, organic field effect transistors (OFETs) and other organic electronic devices. Examples of these compounds include thiophenes, pyrroles and quinolines, which have been widely used to develop high-performance organic semiconductors. Their diverse properties and structures offer a wide range of opportunities for the design and synthesis of new organic electronic materials.