Peng Sheng, Shota Takahashi, Koki Kanemitsu, Takayuki Kiba, Midori Kawamura
Abstract We demonstrate a plasmon-enhanced photoluminescence platform based on Ag/MgO/Ag nanocavities formed by simple thermal annealing. A 5 nm MgO spacer preserves the flatness and reflectivity of the bottom Ag layer while enabling nanoparticle formation in the top Ag film. The resulting hybrid plasmon–cavity modes are modified by an overlaid Alq 3 layer, producing spectral matching around 520 nm. Consequently, Alq 3 emission is enhanced six-fold, exceeding the four-fold enhancement obtained with Ag nanoparticles alone. This lithography-free nanocavity provides a robust route toward efficient plasmon-enhanced light-emitting structures.