New air-stable aromatic polyazomethines with triphenylamine or phenylenevinylene moieties towards photovoltaic application

Two air-stable, donor-type aromatic polyazomethines (PAZ) containing triphenylamine (TPA-3B) or phenylenevinylene (PPV-3B) moieties were synthesized and characterized by 1H, 13C NMR, FTIR, TGA, UV–vis, photoluminescence, electrochemical and spectroelectrochemical measurements, X-ray diffraction (XRD) and atomic force microscopy. The main goal is focused on the electronic application of the two polyazomethines in bulk heterojunction (BHJ) polymeric solar cells. The BHJ solar cells were fabricated with the configuration of ITO/PEDOT:PSS/PAZ:PCBM(or PC71BM)/Al, and the best performance was obtained for the active layer with PC71BM, applied as an acceptor. The device constructed with TPA-3B:PC71BM showed the power conversion efficiency 25 times of magnitude higher than PPV-3B:PC71BM measured using AM 1.5G solar simulator at 100 mW/cm2 light illumination. In addition, in order to control the electrical properties of PAZ on the performance of organic solar cells impedance spectroscopy experiments were done before and after illumination. Moreover, the morphology of PAZ blended with PCBM (and PC71BM) was investigated by AFM. It was confirmed that both the polymer and fullerene derivatives structure plays an important role in the development of air-stable polymer solar cells.