title: Photoinduced charge separation and charge recombination in [60]fullerene-ethylcarbazole and [60]fullerene-triphenylamines in polar solvents.
abstract: Molecules of C60 covalently connected with N-ethylcarbazole (EtCz) and triphenylamine (TPA) have been synthesized. Photoinduced electron transfer in C60-EtCz and C60-TPA has been studied in polar and nonpolar solvents using time-resolved transient absorption and fluorescence measurements. From the fluorescence lifetimes, the excited singlet state of the C60 moiety (1C60) of C60-TPA generates predominantly C60*--TPA*+, which decays quickly to the ground state within 6 ns even in polar solvents. In the case of C60-EtCz, on the other hand, about half of the 1C60 moiety generates short-lived C60*--EtCz*+, while the other half of the 1C60 moiety is transferred to the 3C60 moiety via intersystem crossing in dimethylformamide, in which the energy level of C60*--EtCz*+ is lower than that of 3C60. Thus, the charge separation takes place via 3C60 generating C60*--EtCz*+, having a lifetime as long as 300 ns, probably because of the triplet spin character of C60*--EtCz*+. A special property of the EtCz moiety to stabilize the hole in the charge-separated state was revealed.
authors.affiliation: Institute of Functional Molecular, South China University of Technology, Guangzhou 510641, People's Republic of China. zenghp@scnu.edu.cn
authors.forename: He-Ping
authors.initials: HP
authors.lastname: Zeng
authors.forename: Tingting
authors.initials: T
authors.lastname: Wang
authors.forename: Atula S D
authors.initials: AS
authors.lastname: Sandanayaka
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Araki
authors.forename: Osamu
authors.initials: O
authors.lastname: Ito