The efficiency of light-emitting diodes based on poly[(2-methoxy)-5-(2'-ethyl-hexyloxy)-1,4-phenylenevinylene] increases upon formation of interlayers, on top of poly(3,4-ethylenedioxythiophene) doped with polystyrene sulfonic acid (PEDOT:PSS), made of acid-initiated cross-linkable polyfluorenes. The use of this type of polymers allows for the formation of thicker interlayers leading to higher efficiencies when comparing with similar devices with interlayers formed by the parent non-cross-linkable polymers. This efficiency increase is attributed to a combination of electron and exciton confinement away from PEDOT:PSS.