Light-emitting multifunctional rhenium (I) and ruthenium (II) 2,2′-bipyridyl complexes with bipolar character

A series of multifunctional molecules consisting of hole transport, electron transport, and light-emitting moieties were synthesized and fabricated into single-layer organic light-emitting devices. The light-emitting units were based on 2,2'-bipyridine complexes of rhenium and ruthenium. It was found that, due to the bipolar character of the molecules, the charge carrier mobilities, charge injection barrier, and the device performance were improved. The electron carrier mobilities are on the order of 10(-4) cm(2) V-1 s(-1) and a maximum luminescence of 730 cd/m(2) was observed. (C) 1999 American Institute of Physics. [S0003- 6951(99)04251-5].