Electronic and Light-Emitting Properties of Some Polyimides Based on Bis (2, 2': 6', 2''-terpyridine) Ruthenium (II) Complex
A series of novel aromatic polyimides that contain bis(2,2′:6′,2″-terpyridine) ruthenium(II) complex was synthesized, and their optoelectronic properties were studied. The absorption of the polymers at 500 nm was strongly enhanced by the ruthenium complex. As a result, the photosensitivity of the polymers in the visible region is increased, as can be seen from the increase in photoconductivity. The glass transition temperature of the polymers is approximately 220°C and they also exhibit modest thermal stabilities. The electron and hole carrier mobilities of polyimides are on the order of 10 -4 cm 2 V -1 s -1, which suggests that the electron-withdrawing diimide moieties play a role in the charge transport process. Emission from the metal complexes and charge transfer states were observed in these polymers. The polyimides also exhibited electroluminescent behavior when the polymer films were fabricated into single-layered light-emitting diodes. The external quantum efficiency and maximum luminance of the devices were found to be 0.1% and 120 cd/m 2, respectively. © 1999 American Chemical Society.