Spectroscopical evidences of photoinduced charge transfer in blends of C60 and thiophene-based copolymers with a tunable energy gap

We report a study of the photoinduced charge transfer in the blends of buckminsterfullerene (C-60) and thiophene-based copolymers with tunable energy gap. The photolumiescence and steady state photoinduced absorption spectra evidence the electron transfer from the photoexcited copolymer to C-60 The efficiency of the charge transfer depends on the degree of miscibility of the two components which is easily controlled by the copolymer composition. In the blends obtained with a copolymer with an high energy absorption onset, the spectral signatures of the photoinduced hole transfer to the polymer, arising from the selective excitation of the Coo, are also detected. (C) 2001 Elsevier Science B.V. All rights reserved.