Singlet exciton diffusion in MEH-PPV films studied by exciton-exciton annihilation

We report time-resolved photoluminescence studies in MEH-PPV films for a wide range of excitation intensities. The results fit well to a diffusion-limited exciton-exciton annihilation model with an annihilation constant gamma = (2.8 +/- 0.5) x 10(-8) cm(3) s(-1). This enables us to estimate the exciton diffusion coefficient to be D = (3 +/- 1) x 10(-3) cm(2) s(-1). This corresponds to a diffusion length between 5 and 8 nm for one-dimensional diffusion. (c) 2006 Elsevier B.V. All rights reserved.