Regioregular poly(3-hexylthiophenes) (P3HTs) and its blends were studied regarding their structural and photo-physical properties using fullerene as an electron acceptor material. Photo-physical and structural characteristics of the polymer blends were studied using UV-vis spectroscopy, photoluminescence (PL), Fourier transform infrared absorption (FTIR) spectroscopy and Raman spectroscopy analysis. Films based on the polymer blends with C-60 showed photo-induced absorption characteristic for charged excitations. The absorption spectra of the rr-P3HT exhibit a shift to higher energies (blue shift) of the pi-pi* inter-band transition upon mixing with C-60. A distinctive photoluminescence quenching effect is observed indicating photo-induced electron transfer. The complete reduction of PL of P3HT after mixing with C-60 in a 1:1 weight ratio indicates an effective charge transfer from P3HT to C-60. (C) 2009 Elsevier B.V. All rights reserved.