Electroluminescent properties of functional π-electron molecular systems

Molecules with delocalized pi-electrons possess attractive electroluminescent properties, and have been recently incorporated as the active emissive layers in organic light-emitting devices. In particular, electroluminescent molecular composites using a highly fluorescent guest, with/without carrier trapping properties, and a host with dual luminescent and carrier transport properties are the focus of this study. Devices based on these luminescent functional pi-electron molecular systems exhibited high electroluminescence quantum efficiency, and good thermal and temporal stability, with ease of color tunability. The paper discusses the mechanisms of light-emission that lead to superior performance in these molecular devices. Efficient Forster energy transfer from the host to the guest molecules, and direct carrier recombination at the highly fluorescent guest molecules are proposed as the two mechanisms responsible for high efficiency.