Crosslinkable TAPC-Based Hole-Transport Materials for Solution-Processed Organic Light-Emitting Diodes with Reduced Efficiency Roll-Off



1-Bis[4-[N,N-di(4-tolyl)amino]phenyl]-cyclohexane (TAPC) has been widely used in xerography and organic light-emitting diodes (OLEDs), but derivatives are little known. Here, a new series of solution-processable, crosslinkable hole conductors based on TAPC with varying highest occupied molecular orbital (HOMO) energies from −5.23 eV to −5.69 eV is implemented in blue phosphorescent OLEDs. Their superior perfomance compared with the well-known N4,N4,N4′,N4′-tetraphenylbiphenyl-4,4′-diamine (TPDs) analogues regarding hole-injection and mobility, electron and exciton blocking capabilities, efficiency, and efficiency roll-off is demonstrated. Overall, the TAPC-based devices feature higher luminous and power efficiency over a broader range of brightness levels and reduced efficiency roll off. A systematic broadening of the emission zone is observed as the hole-injection barrier between the anode and the hole-transporting layer increased.