Plasmons excited in a large dense silver nanoparticle layer enhance the luminescence intensity of organic light emitting diodes

We observe that a layer of large (∼300 nm in diameter) closely packed (∼15 nm interparticle separation) silver nanoparticles separated by a spacer layer at least 50-nm thick from a 30-nm-thick Alq3 layer results in the enhancement of bulk luminescence efficiency in the Alq3 layer. To study the potential for practical application of this long-range luminescence enhancement, an organic light-emitting diode (OLED) was fabricated with the silver nanoparticle layer serving as the enhancement element. This device exhibits a luminescence efficiency 4.5 times stronger than that of a similar device with no silver nanoparticle layer. If such an enhancement is applied to deep-blue emissive materials, the efficiency should reach the levels required for practical use. This combination could lead to the broad use of OLEDs in displays and lighting.