Fig. 5: Energy diagram of the PBHM-plasmonic coupled system. Multi-fold Enhancement of Phosphorescence Luminescence in a Plasmonic Structure Xiaolong Zhu,1 Fengxian Xie,2 Lei Shi,1 Xiaohan Liu,1 Jian Zi,1 Wallace Choy,2 Department of Physics and National Laboratory of Surface Physics, Fudan University Department of Electrical and Electronic Engineering, The University of Hong Kong We have experimentally demonstrated multi-fold enhancement and substantial spectral broadening of photoluminescence from organic phosphorescence bulk heterojunction material (PBHM) resulting from resonant coupling to a plasmonic structure. We have also shown that the intensity enhancement and spectral width of the photoluminescence in the combined system are controlled by the spectral overlap of the emission peaks of unmodified PBHM and the structural plasmonic resonances, and thus this effect is linked to exciton-plasmon coupling between PBHM and plasmonic structure. The observed photoluminescence enhancement provides the well-defined demonstration of the cavity Purcell effect in plasmonic structures. (b) (a) (c) (d) (f) (e) Pump light λ = 320 nm Glass substrate PS spheres D = 600 nm Gold film (60nm) CBP:Ir(piq)3 / MoO3 (80 nm / 20 nm) Photo- luminescence Fig. 1: (a) Self-assembly process; (b) SEM of monolayer array of PS spheres; (c) schematic of deposition processes; (d) top-view SEM photo of plasmonic structure functionalized with PBHM; (e) side-view SEM photo of Au/spheres plasmonic structure; (f) side-view SEM photo of plasmonic structure functionalized with PBHM. Fig. 2: Schematic diagram of plasmonic structure functionalized with PBHM and the set-up of phosphorescence photoluminescence of this composite structure. e-h pairs CBP:Ir(piq)3 Exciton-Plasmon Coupling Plasmonic structure Inhomogeneously broadened exciton ensemble Homogeneously plasmon resonances Coupled System Luminescence 1st order 2nd order Fig. 3: Normal-incidence reflection (red solid curve) and emission (bule solid curve) from a PBHM-plasmonic composite structure. The emission spectra from CBP:Ir(piq)3 / MoO3 grown on a glass substrate (black dashed curve) and a plain Au film (red dashed curve) are plotted for comparison. Fig. 5: Energy diagram of the PBHM-plasmonic coupled system. Theory: Prospective application: SPR modulated OLED Phase-match condition: Purcell factor enhancement of luminescence: Q: q-factor; V: mode volume Fig. 4: FDTD simulated reflection spectrum and field distributions of two different SPR modes