Photoinduced electron-transfer processes of the newly synthesized fullerene-diphenylbenzothiadiazoletriphenylamine (C60-PBTDP-TPA) triad in polar and nonpolar solvents have been studied by using time-resolved transient absorption and fluorescence measurements from picosecond to microsecond regions. By fluorescence lifetime measurements in picosecond time regions, excitation of the charge-transfer transition of the PBTDP-TPA moiety in C60-PBTDP-TPA induces energy transfer to the C60 moiety generating 1C60*-PBTDP-TPA, competitively with charge separation generating C60̇--PBTDP-TPA ̇+. From 1C60*-PBTDP-TPA, which is generated directly and indirectly, charge separation occurs generating C 60̇--PBTDP-TPȦ+ in polar solvents. The C60̇--PBTDP-TPȦ+ formed via the singlet excited states decayed within a few nanoseconds as revealed by the picosecond transient absorption spectra. In the nanosecond time region, C 60̇- PBTDP-TPȦ+ is produced slowly, probably via 3C60*-PBTDP-TPA. Lifetimes of such slowly generated C60̇--PBTDP-TPȦ+ were longer than 1 μs, which are the longest values among the C 60-bridge-TPA triad systems reported hitherto at room temperature. Roles of the PBTDP-TPA moiety with twisted intermolecular charge-transfer character playing as energy donor and electron donor in addition to the bridge have been disclosed.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films
- Materials Chemistry