Blue double layer devices obtained by spin-coating

Double spin-coated electroluminescent (EL) devices have been prepared by combining a blue EL arylamine-based hole transport polymer (STPD-QP) in the first spin-coated layer with a blue EL oxadiazole-based electron transport polymer (SP-OX) in the second layer. The luminance and efficiency of these devices are improved by adding PBD, a low molecular weight electron transport oxadiazole derivative, as a solute in the SP-OX layer. Doing so, maximum luminance of ∼1500 cd/m2 and quantum efficiencies up to 0.5% are obtained. Similar luminances cannot be reached by using only solid solutions of PBD in A435, a rather insulating host polymer