Continuous improvement in the materials, processing and device structu
re of light-emitting diodes based on fully conjugated PPV-type polymer
s has led to a performance level suitable for application. In this pap
er we report on the electrical characteristics of large area devices,
and show lifetime data at room temperature of several thousands of hou
rs. In order to come to a more convenient testing scheme, lifetimes ha
ve been measured at higher operational intensity as well as elevated t
emperature and relative humidity. From these data, device degradation
at normal operating conditions can be extrapolated. (C) 1997 Elsevier
Science S.A.