A combinational molecular design to achieve highly efficient deep-blue electrofluorescence

A deep-blue emitter 1-(10-(4-methoxyphenyl) anthracen-9-yl)-4-(10-(4-cyanophenyl) anthracen-9yl) tetraphenylethene (TPEA) has been successfully prepared by a combinational molecular design, which contains triplet-triplet fusion (TTF) and hybridized local charge transfer (HLCT) characteristics to increase the ratio of triplet excitons used. The tetraphenylethene (TPE) moiety contributes the emitter with an aggregation-induced emission (AIE) property to enhance the solid-state luminescence efficiency. The crystallographic structure shows that the two anthracene groups are twisted from the central TPE moiety, which effectively prevents a bathochromic shift of the emission. In addition, we adopted a donor-acceptor (D-A) structure to improve the charge balance in organic light-emitting diodes (OLEDs). The material possesses high thermal stability with a glass transition temperature (Tg) of 155 1C. Based on all these advantages, a high performance of the non-doped device was achieved with a turnon voltage (Von) of 2.6 V at a luminance of 1 cd m(-2), a maximum power efficiency (ZPE, max) of 11.1 lm W-1, a maximum current efficiency (ZCE, max) of 9.9 cd A(-1), and a low current efficiency roll-off even at 1000 cd m(-2). Moreover, a deep-blue emission with Commission Internationale de l'E ' clairage (CIE) coordinates of (0.15, 0.09), a maximum external quantum efficiency (Zext, max) of 8.0% and the highest ZPE, max of 7.3 lm W-1 among all the TTF and HLCT deep-blue emitters were obtained by doping TPEA into the host of bis-4-[(N-carbazolyl) phenyl]-phenylphosphine oxide (BCPO). These results indicate that the combinational molecular design is promising for highly efficient deep-blue emitters.