We present evidence of quantum confinement of the photo-generated states in a conjugated block copolymer consisting of regularly alternating thiophenic and phenylenic moieties of various lengths, thus giving rise to a sort of one-dimensional superperiodicity. CW photoinduced spectra (both in the infrared and in the visible) have revealed localization effects when the width of the potential well exceeds five thiophenic rings. A discussion of the new features in the copolymer photoexcitation spectrum with respect to the parent polymers is also presented.