Pyrimidines are aromatic heterocyclic compounds whose six-membered ring contains two nitrogen atoms at the 1 and 3 positions. They have a variety of electronic properties that make them suitable for electron-donating and electron-accepting roles in semiconductor materials. Pyrimidines can form stable hydrogen bonds, which facilitate the self-assembly and crystallization of semiconductor molecules and enhance charge transport. Their ability to be functionalized allows for the tuning of their optical and electronic properties, making them ideal for a variety of optoelectronic devices. Pyrimidines have been incorporated into small molecule semiconductors for use in OLEDs, OFETs, and solar cells.