Effect of Doping Copper-Phthalocyanine and Annealing Treatment on the Performance of Polymer Solar Cells

We have fabricated poly(3-hexylthiophene) (P3HT)/copper phthalocyanine (CuPc)/fullerene (PC71BM) ternary blend films. This photoactive layer is sandwiched between an indium tin oxide (ITO)/poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT/PSS) photoanode and a bathophenanthroline (Bphen)/Ag photocathode. The thin films have been characterized by atomic force microscope (AFM) and ultraviolet/visible spectroscopy in order to study the influence of CuPc doping on the morphological and optical properties of the photoactive layer. We have also compared the J-V characteristics of two different organic solar cells (OSCs): ITO/PEDOT: PSS/P3HT(0.5):PC71BM0.5/Bphen/Ag and ITO/PEDOT:PSS/P3HT(0.3):CuPc0.3:PC(71)BM(0.)4/Bphen/Ag with and without annealing. Both structures show good photovoltaic behavior. Actually, the incorporation of CuPc into P3HT:PC71BM thin film improves all the photovoltaic characteristics. We have also seen that thermal annealing significantly improves the optical absorption ability and stabilizes the OSCs making it more robust to chemical degradation.