) at 10 -5 M were exposed to continuous irradiation from a 18W white LEDs lamp in presence of oxygen. After two hours, the absorption spectra of the solution remained unchanged, demonstrating an outstanding photostability (Figure and Figure to S47). All polymers were studied by CV (Figure to S41) to estimate their frontier orbital energy. All the polymers displayed excellent electrochemical stability. Combined with the spectroscopy measurements previously detailed, HOMO and LUMO level energies could be estimated. All BACD-based conjugated polymers are good electron acceptors with LUMO energies comprised between -3.72 and -3.96 eV (Table ) a Molar extinction coefficient of the most absorbing band (10 -4 M -1 .cm - 1 ). b Optical band gap in eV determined from the onset of the absorption spectrum recorded in thin films. c HOMO and d LUMO energies in eV.