Singlet Excitation Energy Transfer in the Vinyl Polymers with Pendant Carbazolyl Groups

Abstract

Abstract The migration of electronic excitation energy in films of poly(N-vinylcarbazole) (PVCz) prepared by the radical and cationic polymerizations(PVCz(r) and PVCz(c) respectively), poly[2-(9-carbazolyl)ethyl vinyl ether] (PCz-EVE), brominated PVCz(BPVCz), and poly(9-acryloylcarbazole) (PACz) has been studied by means of fluorescence-quenching experiments, using dimethyl terephthalate or perylene as a guest molecule. No clear difference in the concentration of the effective intrinsic trap sites was observed between PVCz(r) and PVCz(c) films. The concentration of the sandwich-like excimer site(cE) in a PVCz(r) film was nearly equal to that in a PVCz(c) film, while the concentration of the second excimer site (cS) in a PVCz(r) film was higher than that in a PVCz(c) film by a factor of about 1.6. The value of cE was much larger than that of cS for both films. The second excimer site seems to be a shallow trap. The number of carbazolyl chromophores covered by a singlet exciton during the lifetime was in the following order: PCzEVE>PVCz(r)≈PVCz(c)>PACz≈BPVCz. This order was explained by the concentration of the intrinsic trap sites depending on the distance between neighboring Cz chromophores, the lifetime of the singlet exciton, and the concentration of extrinsic trap sites.