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 (similar to 300 nm in diameter) closely packed (similar to 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. (C) 2015 Elsevier B.V. All rights reserved.