Electroluminescence Enhancement with Gold Nanorods in Eu-Based Emission Organic Layer

Europium-based coordination compounds possessing narrow luminescence bands are promising emissive materials for organic light-emitting devices with high colour purity in the red spectral region. However, OLEDs with organic emissive layers based on lanthanides generally suffer from a slow recombination time (≈1 ms), which leads to a relatively low external quantum efficiency. Here, gold nanorods are employed with optimized resonant optical properties for the wavelength range 500–700 nm to modify photo- and electroluminescence from the Eu-based emission layer. Three different emissive europium complexes with a photoluminescence quantum yield of up to 100 % in powder and up to 63% in thin film are used. The experimental results supported by theoretical simulations show that the introduction of gold nanorods in the emission layer results in a 54% increase in the OLED performance. Thus, the highest brightness of solution-processed Eu-based OLEDs is obtained using the Eu(dbm)₃TDZP complex with incorporated gold nanorods.