Sulfone and methoxy substituted block co-polymers of poly-phenlyenevinylene (PPV) have been synthesized and the optical properties of both the oligomers and the combined block co-polymers have been examined. The substitution on the phenylene ring leads to small energy shifts in both the optical band gap as well as shifts in the valence and conduction band energies. When the oligomers are combined in a block co-polymer either with or without an aliphatic bridge unit, a space charge field is formed which can be used to quench the luminescence intensity in these materials by separating optically generated excitons and electron-hole pairs. PPV materials with this internal field have potential applications as solar energy converters and photodetectors. The absorption and emission spectra and the time dependence of the emission of donor and acceptor derivatized block co-polymers was measured and the quenching of the luminescence was observed and quantified.