Pyrimidine-based thermally activated delayed fluorescent materials with unique asymmetry for highly-efficient organic light-emitting diodes

Role of the Intramolecular‐Locking Strategy in the Construction of Organic Thermally Activated Delayed Fluorescence Emitters with Rotation‐Restricted Acceptors

“…For example, TADF emitters based on quinoxaline, [153][154][155] dibenzo-[a,j] phenazine/pyrazino phenanthrene, [139,156] and acenaphtho[1,2b]pyrazine-8,9-dicarbonitrile [157,158] Since Kido et al first reported a pyrimidine-based TADF material in 2016, [141] scientists have performed many structural modifications on pyrimidine-based TADF materials, and the maximum EQEs of the OLED devices based on some of these TADF materials have exceeded 30%. [16,148,[159][160][161] Throughout the development of pyrimidine TADF materials, except for the use of polycyclic-fused pyrimidines to obtain novel pyrimidine-based TADF acceptor units (such as quinazoline) and corresponding high-efficiency TADF materials, [30,162,163] the use of the intramolecular-locking strategy is also an important and effective method. This not only strengthens the rigidity of the molecule, but also reduces the LUMO energy level of the corresponding acceptors, thereby providing a broader space for the design and performance regulation of pyrimidine-based TADF materials.…”