Comparison of mobility and hole current activation energy in the space charge trap-limited regime in a starburst amine

Using two complementary methods, we have investigated the individual contri bution of the space charge-limited hole transport in vapor-deposited films of 4,4('),4(')-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine (m-MTDA TA) to the temperature behavior of organic light-emitting diodes. In single -layer indium tin oxide/m-MTDATA/Ag structures, we have measured the activa tion energies of the current density and of the hole mobility as a function of the applied electric field. Both activation energies obtained under ste ady-state and pulsed conditions are comparable, which confirms that the tem perature behavior of the current density is predominantly governed by the h ole mobility. (C) 1999 American Institute of Physics. [S0003-6951(99)00328- 9].