The fact that C,, is a good acceptor has stimulated interest in covalently
linked complexes, including polymers and oligomers. Photoinduced charge tra
nsfer in these systems has great potential for use in photovoltaic devices.
In this study, an alternating conjugated oligomer of alkylated carbazole a
nd dialkoxyl-substituted phenylene, with pendant C-60 moieties, (PPV-AFCAR)
was prepared and characterized. The excited-state properties of PPV-AFCAR
were investigated with steady-state spectroscopy and lifetime measurements.
After photoexcitation, photoinduced energy transfer from the oligomer chai
n to the pendant moiety occurred in great proportion, but a charge-separati
on process did not. Whether the energy-transfer process was measurable or n
ot depended on the system temperature. At 77 K, a quantum yield of more tha
n 50% for energy transfer was found by the fitting of a linear combination
of the excitation spectra of the precursor oligomer, the alternating conjug
ated oligomer of alkylated carbazole and dialkoxyl-substituted phenylene PP
V-ACAR, and the absorption spectra of C-60. (C) 2001 John Wiley & Sons, Inc