Bias and temperature dependent charge transport in solution-processed small molecular mixed single layer organic light emitting devices

The authors investigate bias and temperature dependent current density-voltage (J-V) characteristics in solution-processed small molecular mixed single layer organic light emitting devices using Au/MoO3 as hole and Al as electron injection electrode. Hole and electron injections are primarily ascribed to the Schottky thermionic emission mechanism. However, at high field of >9 x 10(5) V cm(-1), hole transport is found to be bulk trapped corresponding to space charge limited current with an exponential distribution of traps. The bulk trap density, about 10(18) cm(-3) in mixed organic layer, is evaluated by the differential method. (C) 2011 American Institute of Physics. [doi:10.1063/1.3554391]