Oligo(phenyl-ethynylene)s for electroluminescence and distributed feedbacklaser action

We investigated the electroluminescence (EL) and optically pumped laser emi ssion characteristics of oligo(phenyl-ethynylene)s end-capped with naphtyl groups and bearing dodecyloxy side-chains. Oligomers (oNPEx) made of 3- or 5-aryl groups are dispersed in poly(vinylcarbazole) (PVK) as a hole-transpo rting matrix to study EL properties. The emission spectrum of the trimer oN PE3 is centered at 460 nm, slightly blue shifted with respect to the pure p henyl derivative. The typical diode structure is composed of an indium tin oxide (ITO) anode ITO/oNPEx/PVK/and aluminium cathode. The EL spectrum matc hes photoluminescence (PL). Emission color changes with the concentration f rom violet to blue for oNPE3 and blue to blue-green for oNPE5 and oNPE5b. T hin film of oNPEx/PVK also show laser emission around 447 nm in a distribut ed feedback laser (DFBL) optical pumping scheme. PVK acts in this case as a n amorphous laser host matrix and oNPEx shows laser emission tunable by var ying the incidence angle of the pump beam onto the film. (C) 2001 Elsevier Science B.V. All rights reserved.