Adjusting the emission color of organic light-emitting diodes through aluminum nanodisc arrays

Abstract

With the introduction of phosphorescent and thermally activated delayed fluorescence emitter materials, organic light-emitting diodes (OLEDs) with internal quantum yields of up to 100% can be realized. Still, light extraction from the OLED stack is a bottleneck, which hampers the availability of OLEDs with large external quantum efficiencies. Many different strategies to enhance the outcoupling of the light have been suggested, for instance, the use of collective lattice resonances induced by arrays of plasmonic nanodiscs. Here, we investigate the usability of these nanodisc arrays to tune the emission color of an organic blue-emitting material. By means of extinction and photoluminescence spectroscopy, we show a correlation of the sharp features observed in extinction with a selective fluorescence enhancement. At the same time, the nanodisc array also modifies the microcavity of an OLED stack. For one exemplarily lattice constant of an aluminum nanodisc array directly integrated into an OLED stack, we show that a combination of these effects allows the modification of the emission color from CIE1931 (x,y) chromaticity coordinates of (0.149, 0.225) to (0.152, 0.352). Importantly, the OLED exhibited a similar emission color modification under optical as well as electrical excitation.