Bright oligothiophene-based light emitting diodes

We demonstrate bright and efficient spin-coated yellow organic light emitting diodes (OLEDs) employing as active medium a novel thiophene-based compound, in which the conventional linear structure of the oligothiophenes has been replaced by a branched benzo[b]thiophene-based structure. Such a structure, combined with the oxygen functionalization of the core-thienyl sulphur atom and the cyclohexyl substitution of the lateral thienyl rings, allowed us to obtain a brightness up to 10,500cd/m(2) and an external quantum efficiency up to 0.48%, which are the highest values so far obtained by substituted oligothiophene-based compounds. (C) 2003 Elsevier Science B.V. All rights reserved.