Two pure hydrocarbon molecules of 1,3,5-tris(9-phenyl-9H-fluoren-9-yl)benzene (mTPFB) and 1,3,5-tris(2-tert-butyl-9-phenyl-9H-fluoren-9-yl)benzene (tBu-mTPFB) were synthesized. Due to the conjugation blocked connection mode and rigid/bulky substitutions, these two materials possess high triplet energy, enabling them as good hosts for blue phosphor in PhOLEDs. By studying their thermal, electrochemical, electronic absorption and photoluminescent properties, it was found that the influence of the inert tert-butyl group on material photoelectrical properties is negligible. For instance, mTPFB and tBu-mTPFB showed very similar absorption and emission profiles, with almost the same bandgap, triplet energy and energy levels. However, the encapsulation of tert-butyl on the 2-position of 9-phenylfluorene enhanced material thermal stability. Most importantly, carrier transport properties were improved dramatically, as proved by the mono carrier device. Blue phosphorescent OLEDs hosted by tBu-mTPFB showed external quantum efficiency of 15.2% and current efficiency of 23.0 cd/A, which were much higher than that of the OLEDs based on mTPFB with the analogous structure.

Four pure hydrocarbon molecules of 1,3,5-tris(9-phenyl-9H-fluoren-9-yl)benzene (mTPFB), 4,4′-bis(9-phenyl-9H-fluoren-9-yl)biphenyl (pDPFBP), 1,4-bis(9-phenyl-9H-fluoren-9-yl)benzene (pDPFB) and 1,3-bis(9-phenyl-9H-fluoren-9-yl)benzene (mDPFB), with different connecting modes and cores were prepared in a one-pot reaction. Among them, mTPFB and pDPFDB were newly designed for the study of the structure–property relationship and developing good blue hosts for phosphorescent organic light-emitting devices (PhOLEDs). The four materials show very similar photophysical properties in solution, with almost the same bandgap and triplet energy, as well as similar energy levels. However, their device behavior is quite different with the best performance coming from mTPFB. The conjugation blocked connection mode in the starburst mTPFB molecule with rigid and bulky substituents results in a high triplet energy coupled with good and balanced electron and hole transport, as proved by the internal reorganization energy calculation and mono charge device study, which makes it a good host for a blue phosphor in a PhOLED. The device shows an external quantum efficiency of 15.7% and a current efficiency of 30.6 cd A−1, which is among the best for pure hydrocarbon host based devices.

A new route to various substituted fluoren-9-ones has been developed via an efficient Pd-catalyzed carbonylative multiple C–C bond formation. Under a CO atmosphere, using commercially available aryl halides and arylboronic acids as substrates, this three-component reaction proceeded smoothly in moderate to excellent yields with good functional-group compatibility. The mechanistic investigations suggested a sequential process for the reaction that forms o-bromobiaryls in the first stage followed by a cyclocarbonylation reaction. This chemistry has been successfully extended to construct ladder-type oligo-p-phenylene cores.

A novel Pd-catalyzed C–H functionalization reaction was developed to construct a quaternary carbon center with high yield. This reaction provides an efficient method for the synthesis of 9,9′-diarylfluorenes by direct arylation of monoarylfluorene.

Four pure hydrocarbon molecules of 1,3,5-tris(9-phenyl-9H-fluoren-9-yl)benzene (mTPFB), 4,4′-bis(9-phenyl-9H-fluoren-9-yl)biphenyl (pDPFBP), 1,4-bis(9-phenyl-9H-fluoren-9-yl)benzene (pDPFB) and 1,3-bis(9-phenyl-9H-fluoren-9-yl)benzene (mDPFB), with different connecting modes and cores were prepared in a one-pot reaction. Among them, mTPFB and pDPFDB were newly designed for the study of the structure–property relationship and developing good blue hosts for phosphorescent organic light-emitting devices (PhOLEDs). The four materials show very similar photophysical properties in solution, with almost the same bandgap and triplet energy, as well as similar energy levels. However, their device behavior is quite different with the best performance coming from mTPFB. The conjugation blocked connection mode in the starburst mTPFB molecule with rigid and bulky substituents results in a high triplet energy coupled with good and balanced electron and hole transport, as proved by the internal reorganization energy calculation and mono charge device study, which makes it a good host for a blue phosphor in a PhOLED. The device shows an external quantum efficiency of 15.7% and a current efficiency of 30.6 cd A−1, which is among the best for pure hydrocarbon host based devices.