Simulation of Pentacene/Alq3 Bilayer OLET to Analyze the Effect of Alq3 Layer Thickness and Asymmetric Contacts on Device Performance

This study presents, device simulation of top contact bottom gate Pentacene/tris-(8-hydroxyquinolinato) aluminum (Alq3) bilayer Organic Light Emitting Transistor (OLET) on ATLAS 2-D device simulator. The electrical response of the device is successfully simulated and the effect of different thickness of Alq3 layer on device performance is also studied. During the simulation symmetrical source and drain contacts were considered. The device shows unipolar operation in p-type accumulation mode. However, no signs of light emission observed with symmetrical contacts. It has been demonstrated that the electrical behavior of the simulated device agree well with the experimental results. It is witnessed that the device current drops with increase in Alq3 thickness from 10nm to 20nm, thus degrading device field-effect performance. The dependence of emission on type of contacts and thickness of Alq3 layer has also been studied. It is found that the Langevin Recombination rate used for observing light emission, increases with increase in Alq3 thickness in a Pentacene/Alq3 bilayer OLET with asymmetric contacts, implying that optimisation of Alq3 thickness for light emission is essential.