Thermal Annealing Effect of Subphthalocyanine (SubPc) Donor Material in Organic Solar Cells

We report that the S-shaped kink of current density-voltage (J-V) characteristics, which reduce fill factor of organic photovoltaic cells, can be removed by substrate heating during donor layer deposition process. Subphthalocyanine (SubPc) donor film in combination with buckminsterfullerene (C60) acceptor film has been studied in a planar bilayer donor/acceptor heterojunction by J-V characterization under AM 1.5 simulated illuminations with various thicknesses of SubPc donor film. The substrate heating process enhances hole mobility of SubPc film, resulting 8.7% of efficiency enhancement with markedly improvement of S-shaped kink in J-V curves.