Organic photovoltaics (OPVs) represent a promising renewable energy technology, due to being lightweight and flexible, and enabling fabrication by low-cost solution techniques over large substrate areas. Nevertheless, this technology still faces challenges to become viable on the energy market, namely concerning device lifetimes and efficiency levels, these being only at moderate levels. Furthermore, solution-processed OPVs use toxic aromatic solvents for depositing the active layer, which are not sustainable for mass production.
In this communication, new conjugated polymers, based on electron accepting moieties and with solubility in solvents of low toxicity (e.g. ethanol), are presented. The solubility in such solvents is provided by lateral hydrophilic groups (oligoether chains) attached to conjugated units based on quinoxaline and benzothiadiazole moieties. New electron-donor polymers with analogous solubilizing chains were also synthesised. The synthesis of the new materials, their opto-electronic properties, and applications in OPV devices, as the active layer, are reported.