Composite metal-oxide polymer-based electroluminescent diodes are designed to obtain air stable operation along with sub-volt turn on and high brightness. We investigate different structures (mesoporous and compact) and different materials (TiO2 and ZnO) for electron injecting layers, and employ MoO3 for hole injecting layers. The highest efficiencies, close to 3 Cd A(-1), are achieved using compact ZnO.