Synthesis of dual-emissive polymers based on ineffective energy transfer through cardo fluorene-containing conjugated polymers

We describe here the design and synthesis of the conjugated polymers containing dye-modified cardo fluorenes for the dual emissions. Mono and di-substituted cardo fluorenes with boron dipyrromethene (BODIPY) were introduced into alternating conjugated polymers using bis-thienyl-benzothiadiazole as a comonomer for constructing the donor (D)-acceptor (A) pairs through the main-chains. The polymeric products showed good solubility in the common organic solvents and good film-formability. Strong emissions were obtained from the synthesized polymers in both solution and film states. In particular, multi-color emissions in green and red regions derived from each component were observed from the solutions containing the synthesized polymers. From the emission lifetime measurements, it was found that the energy transfer should be suppressed between the side and the main-chains, leading to the dual emission from the polymers. Furthermore, we also observed that the synthesized polymers have the light-harvesting antenna (LHA) effects and the color tunability by changing the number of BODIPY dyes tethered to the cardo fluorene.