Ethynylene‐Linked Oligomers Based on Benzodithiophene: Synthesis and Photoelectric Properties

Two conjugated ethynyl‐linked oligomers, oligo(benzodithiophene‐ethynylene‐benzothiadiazole) (O1) and oligo(benzodithiophene‐ethynylene‐carbazole) (O2), were synthesized by Sonogashira coupling reaction. Their degrees of polymerization were 7 and 10, respectively. Their photophysical and electrochemical properties were investigated. O1 exhibitd two strong absorption bands at 404 nm and 483 nm, and O2 at 401 nm and 429 nm. The results of UV‐Vis, cyclic voltammetry (CV) and theoretical calculations showed that O1 has a narrower band gap than O2. The conductivities of O1 and O2 were 1.05×10^?15 and 6.98×10^?16 S/cm, respectively, and would increase to 1.23×10^?10 and 1.05×10^?10 S/cm after doping with iodine.