Low-voltage organic electroluminescent devices using pin structures

We have realized a small-molecule organic light-emitting diode where the intrinsic emitter layer is sandwiched by n- and p-doped transport layers with appropriate blocking layers. The diodes based on this pin concept have exponential forward characteristics up to comparatively high current densities. The diodes reach high brightness at very low operating voltage: for instance, 1000 cd/m(2) at a voltage of 2.9 V. Despite the highly doped transport layers, the devices reach very high efficiency for the given emitter system up to high brightness. (C) 2002 American Institute of Physics.