Effect of electron withdrawing or donating substituents on the photovoltaic performance of polythiophenes

Polymers and copolymers from thiophenes and substituted thiophenes are of interest in the field of photovoltaics. This paper presents the results from investigations into the use of novel copolymers of bithiophene with para-substituted (E)-3-styrylthiophenes in photoelectrochemical cells. These new materials were electrosynthesised and characterised by cyclic voltammetry, UV–VIS spectrophotometry, elemental analysis, and four point probe conductivity measurements before being tested in photoelectrochemical cells. The effects of electron withdrawing groups (–NO2 and –CN) and the electron donating group –NMe2 on the copolymer properties, including photovoltaics, were investigated. In addition, the effect of the redox states of these materials on their photovoltaic responses was also considered.