Poly(3-butylthiophene) nanowires inducing crystallization of poly(3-hexylthiophene) for enhanced photovoltaic performance

Poly(3-butylthiophene) nanowires (P3BT-nws) were incorporated into poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) to modulate the morphology of the active layer for enhanced photovoltaic performance. The P3BT-nws were found to induce the crystallization of P3HT as revealed by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Furthermore, the existence of P3BT-nws facilitated the aggregation of PCBM molecules into larger clusters as revealed by grazing-incidence small angle X-ray scattering (GISAXS). The power conversion efficiency of the ternary blend device could reach the highest value of 4.2% at a P3BT-nw weight percentage of 7 wt%, in comparison with the pristine P3HT: PCBM system of 3.0%. The improved performance should be associated with the enhanced hole and electron mobilities, due to the formation of interconnected pathways along the crystallites of P3HT and P3BT-nws for efficient long-range charge transport.