Current-induced chain migration in semiconductor polymer blends

Abstract

We have used the technique of neutron reflectometry in order to evaluate the changes that occur within polymer light-emitting devices as they are operated. The devices examined consisted of an indium-tin-oxide, anode, a deuterated-poly(styrene sulfonate)/poly(3,4 ethylenedioxythiophene), ($d$-PSS/PEDT), charge injection layer, poly(fluorene), (F8), and a low work-function cathode. We found clear evidence for segregation of $d$-PSS to the $d$-PSS:PEDT/F8 interface in a device driven until its brightness had fallen to 10% of its initial value. We suggest that this effect is due to Joule heating of the device during operation.