Poly(9,9-di-n-octylfluorene-2,7-vinylene)s (PFVs) containing an oligo(thiophene) moiety at the chain ends have been prepared and identified. Fluorescence spectra of PFVs containing 3 or 4 thiophene repeat units at the chain ends showed significant difference in their intensities at ca. 500 and 530 urn from those containing others (2 or 5 thiophene repeat units, etc.). The emission intensities were dependent upon the degree of fluorene-2,7-vinylene repeat unit (PFV conjugation length); the observed differences are thus attributed to an energy transfer from the PFV conjugated main chain to the oligo(thiophene) moieties.