P-I-N-P top-emitting organic light-emitting diodes with MoOx as the electrical and optical modification layers

We report a P-I-N-P top-emitting organic light-emitting diode (TEOLED) that contains an additional p-doped hole transporting layer between the conventional n-doped electron transporting layer and the top cathode. The TEOLED comprises MoOx in different positions of the device stack (i) as a buffer layer and a p-dopant to improve the hole injection efficiency from the anode side and to form an abrupt tunnel junction at the cathode side and (ii) a capping layer to tailor the out-coupling efficiency. The N-P tunnel junction provides a simple approach for balancing charge injection and thus results in simultaneous improvements on current, power and external quantum efficiencies (maxima of 39, 35, and 45%, respectively).