A new diamine as the hole-transporting material for organic light-emittingdiodes

A new diamine, N,N-diphenyl-N,N'-bis-biphenyl-(1,1'-biphenyl)-4,4'-diamine (PTPD), has been synthesised to be applied as a hole-transporting material for multilayer organic light-emitting diodes (LEDs), Electrical and optical characteristics of a series of double-layer (DL) LEDs using PTPD as hole-t ransporting layers (HTL) and Alq(3) and Znq(2) as electron-transporting lay ers have been measured and compared with those for DL LEDs based on other H TLs (TPD and NTPD), The differences are discussed in terms of charge inject ion at the electrodes and electron-hole recombination processes at the orga nic interfaces. The prerequisites based on the molecular structure of the c ompound, confirmed by preliminary experimental observations, suggest PTPD t o be a stable hole-transporting material for high-durability organic LEDs, Copyright (C) 2000 John Wiley & Sons, Ltd.