Improved power efficiency in blue phosphorescent organic light-emitting diodes using diphenylmethyl linkage based high triplet energy hole transport materials

Improved power efficiency in blue phosphorescent organic light-emitting diodes (PHOLEDs) was demonstrated by using new high triplet energy hole-transport materials based on the diphenylmethyl linkage. Two high triplet energy hole-transport materials with diphenylamine or ditolyamine moieties linked through a diphenylmethyl linkage, 4,4′-(diphenylmethylene)bis(N,N-diphenylaniline) (TCBPA) and 4,4′-(diphenylmethylene)bis(N,N-di-p-tolylaniline), were synthesized and evaluated as hole-transport materials for blue PHOLEDs. The power efficiency of TCBPA was superior to that of standard 1,1-bis[4-[N,N′-di(p-tolyl)amino]phenyl]cyclohexane.

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► Diphenylmethyl linkage based high triplet energy hole transport materials.
► High power efficiency in blue phosphorescent organic light-emitting diodes.
► High triplet energy over 2.75 eV.