OBSERVATION OF THE TEMPERATURE DEPENDENCE OF THE DYNAMICS OF PHOTOEXCITED STATES IN PRISTINE TRIS(8-HYDROXYQUINOLINE) ALUMINUM (ALQ_3)

摘要

We have investigated the temperature dependence of the dynamics of radiative excited states in pristine thin films of tris(8-hydroxyquinoline) aluminum (Alq_3). By measuring the transient photoluminescence (PL) response with subnanosecond resolution, our results revealed an increase in the radiative excited state lifetime and fluorescence quantum yield with decreasing temperature from 300K to 77K. At low temperature we observed a decrease in the bimolecular recombination rate constant, singlet exciton diffusion coefficient and diffusion length. A singlet exciton trapping model is used to explain these results.