An amphiphilic diblock-copolymer consisting of poly(3-hexylthiophene) and poly(4-vinylpyridine) has been synthesized and self-assembled from mixed selective solvents of tetrahydrofuran and methanol to produce nanostructures having photoluminescence spanning from the blue to the red. The emission decay times of the nanostructures have been found to increase with the fraction of methanol, suggesting that the probability of the nongeminate recombination of relaxed S-1 excitons decreases with the increase of medium polarity. The emission decay times are shorter at 690 nm than at 650 nm, indicating that two-dimensional interchain effect is more important for the 0-1 vibronic transition than for the 0-0 transition. The initial intensity percentage of the fast component of biphasic emission decay is much larger with excitation at 532 nm than with excitation at 355 nm, suggesting that other charge carriers such as polarons are generated rapidly from S-1 excitons in competition with vibrational relaxation. (C) 2016 Elsevier Ltd. All rights reserved.