The influence of molecular structural factors of covalently bound porphyrin-fullerene dyads and porphyrin—fullerene binary mixtures on photocurrent in model photoelectrochemical cells was studied. It was found that the photocurrent increased either by introducing solubilizing alkyl groups into the donor (porphyrin) or acceptor (fullerene) fragments, or by covalent binding porphyrin and fullerene into a donor-acceptor dyad.