Metal-induced photoluminescence quenching of tri-(8-hydroxyquinoline) aluminum

Abstract

Metal-induced photoluminescence (PL) quenching of organic thin film [tri-(8-hydroxyquinoline) aluminum (Alq)] has been investigated both experimentally and theoretically. By doing experiments in situ in high vacuum, we have measured the PL intensity of Alq film deposited on metal-doped Alq film or metal film as a function of its thickness. For the case of metal-doped Alq film, exciton diffusion length of Alq is derived as $L_D=8.6\pm 0.1\mathrm{nm}$ by analyzing experimental results and using a model based on diffusion and interface dissociation of excitons. For the case of metal film, another model considering exciton diffusion, interface dissociation, and nonradiative energy transfer to the metal is suggested to explain the experimental observation. Good agreement is achieved between theory and experiment.