High triplet energy exciplex forming hole type host for high performance in deep-blue phosphorescent organic light-emitting diodes

We designed and synthesized hole type host, N,N-bis(4-(tert-butyl)phenyl)-3,5-bis(3,6-di-tert-butyl-9H-carbazol-9-yl)aniline (t-DCDPA) to use as an exciplex host with 2,8-bis(4,6-diphenyl-1,3,5-triazin-2-yl)dibenzo[b,d]furan (DBFTrz) electron type host material in deep-blue phosphorescent organic light-emitting diodes (PhOLEDs). To evaluate ability of t-DCDPA, other hole type host materials were used as reference materials, which are tris(4-(9H-carbazol-9-yl)phenyl)amine (TCTA) and 3,5-di(9H-carbazol-9-yl)-N,N-diphenylaniline (DCDPA). Three pairs showed red-shifted emission compared to that of each host emission, which means that they formed exciplex. t-DCDPA:DBFTrz pair showed triplet energy of 2.94 eV, which is similar to that of DCDPA:DBFTrz pair (2.95 eV) and higher than TCTA:DBFTrz (2.83 eV). In deep-blue PhOLEDs, t-DCDPA:DBFTrz host pair showed the highest performance among three pairs, which proved that the newly synthesized host is efficient in deep-blue PhOLEDs.