The influence of CuPc nanoparticles adding on the performances of photovoltaic cells based on P3HT:PC71BM polymeric blend

In this study, we report the fabrication and characterization of innovative photovoltaic cells prepared by adding small molecules of copper phthalocyanine (CuPc) either into the hole transport layer (HTL) or to the active layer. The active layer of the conventional photovoltaic cell was grown as a 1:1, wt% ratio mixture between a conductive polymer, poly (3-hexylthiophene-2,5-diyl (P3HT) as donor (D), and a fullerene derivative, [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) as acceptor (A). The contribution of the CuPc adding was investigated by its participation to the photogeneration process into the D1:D2:A, type ternary absorber layer P3HT(D1):CuPc(D2):PC71BM(A) or by the improvement of the hole transport properties as blending with the (3,4-etylenedioxylenethiophene):polystyrene sulphonic acid (PEDOT:PSS), used frequently as a conventional HTL. The individual layers PEDOT:PSS, P3HT:PC71BM and customized layers PEDOT:PSS + CuPc (0.75:0.25, wt%), P3HT:CuPC:PC71BM at three different concentrations, 0.75:0.25, 0.50:0.50, 0.25:0.75 wt%, were deposited by spin-coating, at room temperature. The electrical and photo-electrical properties of prepared structures were investigated by current-voltage characteristics in the dark and at illumination, in AM 1.5 conditions (100 mW/cm2), respectively. This study showed that the presence of CuPc small molecules in the active layer of a photovoltaic device, for a certain weight ratio, significantly improves the diode-like behavior.