High PL quantum efficiency of poly(phenylene vinylene) systems through exciton confinement

Photoluminescence (PL) quantum efficiency is a key issue in designing succe ssful light-emitting polymer systems. Exciton relaxation is strongly affect ed by exciton quenching at nonradiative trapping centers and the formation of excimers. These factors reduce the PL quantum yield of light-emitting po lymers. In this work, we have systematically investigated the effects of ex citon confinement on the PL quantum yield of an oligomer, polymer, and alte rnating block copolymer (ABC) PPV system. Time-resolved and temperature-dep endent luminescence studies have been performed. The ABC design effectively confine photoexcitations within the chromophores, preventing exciton migra tion and excimer formation. An unusually high (PL) quantum yield (above 90% ) in the solid state is reported for the alternating block copolymer PPV, a s compared to that of similar to 30% of the polymer and oligomer model comp ounds. (C) 2000 Elsevier Science S.A. All rights reserved.