High performance green–yellow light copolymer electroluminescent devices have been fabricated by using a soluble copolymer material, poly(2,5-dimethoxy-p-phenylenevinylene-co-styrene) (DMeO-PPV-co-PS). A bilayer device of configuration ITO/DMeO-PPV-co-PS (70 nm)/BBOT (50 nm)/Al (100 nm) exhibited a maximum luminance of 1550 cd m−2 and a turn-on voltage of 6.2 V. Compared with the single-layer copolymer device ITO/DMeO-PPV-co-PS/Al, the turn-on voltage decreases from 13.0 to 6.2 V and the maximum luminance increases from 230 cd m−2 to 1550 cd m−2.