The function of a conjugated oligoelectrolyte (COE) as the electron transport layer (ETL) in polymer light emitting diodes is demonstrated. Current density-luminance-voltage characteristics demonstrate that insertion of the COE adjacent to an At electrode yields higher device efficiencies than those obtained using the low work function cathode Be. Furthermore, the temporal response of the electroluminescence is faster than that observed when using conjugated polyelectrolytes as the ETL. That COEs have better defined structures than their polymeric counterparts may make them more attractive materials for the fabrication of efficient PLEDs prepared by spin coating methods.