Fig. 15. (a) Absorption spectra of anthracene (light blue), pyrene (dark blue), and perylene (green) dispersed in a PMMA matrix with a concentration of 0.01 mol% as well as of CDs in aqueous solution (black dashed line). (b) Normalized PL spectra of the same samples as in (a) excited at 337 nm. (c) Normalized PL spectra of pyrene in PMMA films excited at 337 nm, as a function of pyrene concentration with the CD PL spectrum (black dashed line) for comparison. (d) Scheme of the exciton self-trapping process in a pyrene molecule pair: a free exciton (blue spot) may be self-trapped on a molecule pair as a self-trapped exciton (red spot), causing the reduction of energy and mobility. Figure reproduced from ref. 208 with permission from American Chemical Society, copyright 2015.