We demonstrate that mixing insulating oxide nanoparticles into electroluminescent polymer materials results in increased current densities, radiances, and power efficiencies in polymer light emitting diode devices. For low driving voltages, an order of magnitude increase in current density and light output is achieved with minimal loss in device lifetime. At 5 V, we achieve radiances of 10 000cd/m2with external quantum efficiencies ∼1&percent; for nanoparticle/MEH–PPV composite films. ©1997 American Institute of Physics.