Properties of Highly Efficient Charge Generation and Transport of Multialternating Organic Heterojunctions and Its Application in Organic Light-Emitting Diodes

The highly efficient charge generation and transport is realized by simply stacking several 1,4,5,8,9,11-hexa-azatriphenylene hexacarbonitrile (HAT-CN)/4,4',4"-tris(N-3-methylphenyl-N-phenylamino) triph-enylamine (m-MTDATA) organic heterojunctions in series. Mechanism analysis confirms that the highly effective charge transport property benefits from the efficient charge generation and recombination processes at the HAT-CN/m-MTDATA interfaces. It is found that the efficient multialternating organic heterojunctions can be used not only as hole and electron transporters to supply large charge injection, but also as excellent charge generation layer (CGL) to fabricate high-performance tandem organic light-emitting diodes (OLEDs). The resulting red phosphorescent OLEDs by simultaneously using the multialternating organic heterojunctions as hole and electron transporters realize the power efficiency (PE) of 36.7 lm W-1, current efficiency (CE) of 28.0 cd A(-1), and external quantum efficiency (EQE) of 15.4%, whereas the PE, CE, and EQE, respectively, reach 37.1 lm W-1, 56.0 cd A(-1), and 31.8% when simultaneously using the multialternating organic heterojunctions as hole and electron transporters and CGL to fabricate tandem red phosphorescent OLEDs, indicating the validity of the multialternating organic heterojunctions as the charge generator and transporters. The results provide us a totally new way of fabricating high-performance OLEDs.