Recent progress of pyrimidine derivatives for high-performance organic light-emitting devices

Pyrimidine is an electron-deficient azaaromatic compound containing two nitrogen atoms at 1, 3-positions that plays a key role as an organic semiconductor or semiconducting material. Because of the high electron-accepting property induced by C═N double bonds and due to its coordination ability, pyrimidine has been incorporated as a building block in phosphorescent emitters, fluorescent emitters, bipolar host materials, and electron transporting materials in organic light-emitting devices (OLEDs). Recently, pyrimidine-based thermally activated delayed fluorescent emitters combined with various electron donors have been developed, and their device performances were far better than those based on conventional fluorescent emitters. In this review, recent progress of pyrimidine-based OLED materials is presented and accompanied by a historical overview, current status, key issues, and outlook for the next generation of high-performance OLED materials.