Abstract

Semiconducting and luminescent π-conjugated polymers offer a number of important advantages over conventional inorganic semiconductors for light-emitting-diode (LED) applications. The ability to after the π-π^* energy gap through controlled changes in the molecular structure promises to provide colors that span the visible spectrum, the ability to fabricate the LEO structure by casting the active luminescent polymer layer from solution promises a significant manufacturing advantage, and the ability to construct plastic LED’s promises to permit the fabrication of flexible light sources in a variety of unusual shapes. Initial results from such polymer LED’s have already demonstrated that various colors (red, yellow, green, and blue) can be realized with impressive efficiency, brightness, and uniformity. The unique processing advantages and mechanical properties of polymers have been demonstrated through the fabrication of flexible LED structures in which the hole-injecting polymer electrode and the semiconducting luminescent polymer layer are spin cast from solution onto a transparent polymer substrate. Switching on and off is RC limited; polymer LED’s have been fabricated with on and off transients in the 10–50-ns regime. The fast response plus the linearity of the light output with current implies that multiplexing will be possible.

© 1993 Optical Society of America