Impact of solution casting temperature on power conversion efficiencies of bulk heterojunction organic solar cells

• The ideal temperature of blend solution for spin casting is investigated in this study.
• P3HT:PCBM blends yield highest efficiency for the blend solutions spin coated at ∼60 °C.
• The surface morphology of films prepared at the ideal casting temperature changes little after annealing.

The power conversion efficiency (PCE) of P3HT:PCBM bulk heterojunction solar cells highly depend on the processing conditions of the blend film. Among many factors investigated, the effect of blend solution temperature for spin casting on PCE of solar cells is currently missing in the literature. In this work, we have systematically analyzed the effect of solution casting temperature on solar cell performance of P3HT:PCBM bulk heterojunction layer. We have found that the ideal casting temperature is ∼60 °C for the blends. Further annealing of the blend does not change the surface morphology substantially at the ideal temperature as opposed to the films prepared at other temperatures.