Plasmonic Enhancement and Angular Control of Narrow-Emitting Europium-Based Luminescence

Eu-based emitters are known to offer narrow-band red luminescence, making them ideal for use as OLEDs. However, their long excited-state lifetime limits device efficiency compared to other materials. This paper aims to demonstrate that the integrating plasmonic resonances can reduce the lifetime and enable the directional emission outcoupling of various kinds of luminescent materials. Here, we employ one-dimensional aluminum plasmonic crystals (PCs) to control the directionality of photoluminescence in Eu(dbm)₃(TDZP) (dbm = dibenzoylmethanate, TDZP = thiadiazolophenanthroline). The PCs with tailored periodicity were fabricated to achieve spectral overlap between surface plasmon resonances and the electric dipole transition of europium at 612 nm. Tuning periodicity directed the emission to near ±7° with a narrow angular divergence of 5°. At the resonance, the 4-fold enhancement in photoluminescence intensity was observed. Coupling the emission with surface plasmons and outcoupling it to the far-field decreased the lifetime of Eu(dbm)₃(TDZP) by 1.7 times. This study therefore demonstrates the potential of plasmonic engineering to overcome the limitations of lanthanide emitters.