A series of novel carbazole-based soluble copolymers of different composition was synthesized by Suzuki coupling reaction. Efficient energy transfer from the wide-band-gap segment polycarbazole due to excition trapping on narrow-band-gap bis(thienyl)benzothiadiazole sites has been observed. Maximum electroluminescence wavelengths of the copolymers varied between 668 nm and 716 nm, and the external quantum efficiency for copolymer devices is 0.3% for copolymers with 20% benzothiadiazole content.