Abstract
We prepare two layers organic light-emitting diodes (OLED) composed of small molecular materials. Organic multilayers are accumulated by spin-coat method on polyethylene terephthalate/indium-tin oxide (PET/ITO) substrate. The multilayer is investigated by measurement of current density as a function of applied voltage at three different positions. Among these points, at the one farthest from the rotating center in the spin-coat process, the largest current density of 1.1 mA/cm2 is observed under a bias voltage of 20 V. For this point linear relationship in lnJ versus V1/2 and lnJ/V versus V1/2 indicate that the electronic conduction originates from Schottky and a hopping mechanism of carriers. At the other positions, where film thickness is thinner, tunneling current is expected.
