Numerical simulation of charge carriers distribution and the relevant electric fields in host–guest systems of small molecules

Abstract

The Monte Carlo method has been used to simulate the average number of injected electrons and the related electric potential and field distributions in a single film of tris-(8-hydroxyquinoline) aluminum (Alq 3 ) and 8-hydroxyquinolinato lithium (Liq) blend which is sandwiched between two electrodes of Al. In our simulations, two correlated and uncorrelated states have been taken into account for the energy of the charge carriers which are located on a 3D simple cubic lattice of sites. The layer averaged number of charges is maximized near the injecting and collecting electrodes, and it decreases as the distance increases from the electrodes for the two states. Moreover, results show that the layer averaged number of charges is higher in pristine Alq 3 , as compared to other materials in the study, but no change is observed in the width of space charge regions in the materials. The electric field distribution related to the electrons injected into the materials is non-uniform, and it has higher values near the electrodes than other places. The electric field distribution shows a nonlinear behavior when the concentration of Liq increases in the Alq 3 host, although it moves towards a linear state, and the magnitude of electric field increases as the blending ratio decreases.