Optical and EPR spectroscopy in pure and blended films of a novel low band gap polymer

Abstract

Efficient charge transfer between a newly synthesized low band gap (LBG) conjugated polymer and the C-60 derivative PCBM is demonstrated. Spectral and time-resolved photoluminescence (PL) measurements show strong quenching and charge separation in the picosecond time range. The charge transfer is further confirmed by light-induced electron paramagnetic resonance (EPR) measurements of both the positive polarons and the fullerene radicals, which can be resolved in high-frequency EPR. The potential for the LBG polymer to act as acceptor was examined in blends with the para-phenylene-vinylene polymer MDMO-PPV. No charge transfer, but instead energy transfer from MDMO-PPV to LBG occurs in these blends, as shown by PL spectroscopy.