Molecular engineering of pyrimidine-containing thermally activated delayed fluorescence emitters for highly efficient deep-blue (CIE y < 0.06) organic light-emitting diodes

Diazine-based thermally activated delayed fluorescence chromophores

“…Following this line, Zhang and coworkers have designed derivatives 13 and 14 using 5H-benzofuro-and 5H-benzothieno[3,2-c]carbazole ED groups (Chart 5). 51 Both derivatives exhibit similar photophysical properties, with slightly lower DE ST , PLQY and delayed emission lifetime for the oxygen derivative 13 (Table 1). Deep blue emitting…”

“…In this case, however, the central pyrrole ring of carbazole is not always able to induce sufficiently large steric effect to maintain a quasi-perpendicular arrangement with the EA part of the push-pull structure upon excitation necessary to observe spatially separated HOMO and LUMO orbitals and small enough DE ST . 47,48 The carbazole fragments can be connected directly to the pyrimidine core by simple nucleophilic substitution or by Buchwald-Hartwig Pd-catalyzed cross-coupling reaction from chloropyrimidine derivatives, 49 whereas 9-phenyl-9H-carbazole fragments can be grafted onto the pyrimidine core by Pd-catalyzed Suzuki cross-coupling reaction from chloropyrimidine derivatives and the corresponding boronic acids/esters, 50 by Ullman coupling from the corresponding bromophenylpyrimidine 51 or by nucleophilic substitution from the corresponding fluorophenylpyrimidine. 52 Serevičius and coworkers have designed a couple of 4,6-di(9H-carbazol-9-yl)pyrimidine derivatives 1 (Chart 1).…”

Molecular Engineering of Isomeric Benzofurocarbazole Donors for Photophysical Management of Thermally Activated Delayed Fluorescence Emitters

“…Amongt he many carbazole-derived donors, the benzofurocarbazole moiety has proved to be effective as a donori nT ADF materials,a si tm oderates the donorc haracter of the carbazole moiety. [27][28][29][30] The benzofurocarbazole donori s also known as as table donorm oiety,e nabling high efficiency and stable driving of TADF emitters. However,o nly one benzofurocarbazole donor,5 H-benzofuro[3,2-c]carbazole (34BFCz), has hitherto been reported in the literature, [31][32][33] although several benzofurocarbazole isomers are potentially available for TADF emitters.T herefore, the synthesis of benzofurocarbazole isomersa nd further study of their application as donors in TADF emitters is needed to achievee nhanced TADF device performance.…”

“…TADF device performances using carbazole‐derived electron‐donor moieties are shown in Table S1. Among the many carbazole‐derived donors, the benzofurocarbazole moiety has proved to be effective as a donor in TADF materials, as it moderates the donor character of the carbazole moiety . The benzofurocarbazole donor is also known as a stable donor moiety, enabling high efficiency and stable driving of TADF emitters.…”

Pyrazine-Based Blue Thermally Activated Delayed Fluorescence Materials: Combine Small Singlet–Triplet Splitting With Large Fluorescence Rate

“…Cyano (Uoyama et al, 2012; Li B. et al, 2014; Lee and Lee, 2015; Taneda et al, 2015; Zhang et al, 2016; Chan et al, 2018; Sommer et al, 2018) and aromatic imines [i.e., triazine (Endo et al, 2011; Lee et al, 2012; Tanaka et al, 2012; Hirata et al, 2015; Kaji et al, 2015; Cha et al, 2016; Lin et al, 2016; Zhu et al, 2016; Chen X.-K. et al, 2017; Cui et al, 2017; Shao et al, 2017; Liu Z. et al, 2018; Oh et al, 2018; Zhang Q. et al, 2018; Wang Q. et al, 2019; Zhang et al, 2019) pyrimidine (Gómez-Bombarelli et al, 2016; Komatsu et al, 2016; Pan et al, 2016; Wu et al, 2016; Ganesan et al, 2017; Nakao et al, 2017; Park et al, 2017; Xiang et al, 2017; Zhang Q. et al, 2018; Zhang et al, 2019), and pyridine (Tang et al, 2015; Pan et al, 2016; Rajamalli et al, 2017; Sasabe et al, 2017; Chen et al, 2018)] are the most used groups for the construction of acceptor moieties in TADF molecules. The electron-withdrawing capability of an aromatic imine increases with an increase in the number of nitrogen atoms in the ring.…”