Dynamics of photoexcited states and charge carriers in organic thin films: Alq3

We demonstrate a method for observing and analyzing the dynamics of photoexcited molecular states and charge carriers in organic thin films, by measuring simultaneously the transient photoluminescence and photoconductivity. We show experimentally in tris-(8-hydroxyquinoline) aluminum (Alq3) that exciton–exciton annihilation dictates the behavior of the photoluminescence and photoconductivity at high excitation intensities. The experimental results are corroborated by calculations based on an exciton-exciton annihilation model.