Efficiency enhancement of P3HT:PC₆₁BM bulk heterojunction solar cells by doping with a small molecule dye

In this study, we have enhanced the power conversion efficiency of polymer solar cell by physically doping with an organic dye into the active layer of polymer solar cells. The organic dye has complementary absorption wavelength against the polymer active layer and energy transfer effect to increase the photovoltaic current of polymer solar cells. We chose 2,3,9,10,16,17,23,24-octakis(octyloxy)-29H,31H-phthalocyanine (OPc) as an organic dye and analyzed OPc's characteristics with cyclic voltammetry (CV), UV-vis spectrometry and thermogravimetry analysis (TGA). The polymer solar cells were fabricated by blending of the organic dye into the active layer (P3HT/PC₆₁BM) with different concentrations (1.63 wt%, 3.22 wt%, 4.76 wt%, 6.30 wt%). The doped devices showed 19% increase in the power conversion efficiency (PCE). It was proved that the increase of efficiency was due to the increase of photovoltaic current based on the measurement of external quantum efficiency (EQE).