Experimental and theoretical study of tris-(8-hydroxyquinoline) aluminum (Alq3) photoluminescence enhanced by self-assembled silver films

Abstract

Alq3 photoluminescences (PL) enhanced by self-assembled silver films are investigated experimentally and theoretically. The experimental results show that both the apparent enhancement factor (AEF) and the emission enhancement factor (EEF) of Alq3 PL increase with the increase of density of average 70 nm diameter silver nanoparticles on the substrate. The maxima of AEF and EEF are about 3.2 and 13, respectively. Based on the optical antenna theory, the theoretical maxima of both quantum efficiency enhancement factor and EEF of Alq3 PL are about 1.4 and 15, respectively. By comparing of the experimental results with the theoretical results, we can conclude that the near-field enhancement of silver nanoparticles makes a major contribution to Alq3 PL emission enhancement, and the emission enhancement is dependent on the Alq3-silver nanoparticle distance and the area coverage ratio of silver nanoparticles to substrate.