Organic light-emitting diodes with a bipolar transport layer

A structure based on a bipolar transport/emitting layer is proposed and imp lemented for making organic light-emitting diodes. Compared to the conventi onal heterojunction organic light-emitting diodes, more than a factor of si x improvement in device reliability (a projected operating lifetime of 70 0 00 h) is achieved in the structure. The significant improvement in device l ifetime is attributed to the elimination of the heterointerface present in the conventional devices which greatly affects the device reliability. (C) 1999 American Institute of Physics. [S0003-6951(99)04324-7].