Effects of the processing variables on the optical properties of P3HT:PCBM absorber layer: A statistical point of view

The organic solar cells (OSCs) stand out due to their low cost and possibility to be flexible; however, it is well known that small deviations of the manufacturing variables could affect their performance. Therefore, in this work, we conducted a systematic study of the effects of the precursor solution (PS) processing and the post -deposition thermal treatment (TT) on the optical properties of P3HT:PCBM absorber-layer, by applying a Cen-tral Composite Design of Experiments. Results revealed that the temperature is the factor with the greatest in-fluence on material properties; while the stirring time by itself is the least significant; however, its interaction with high temperature promotes the structural disorder, inducing degradation of the absorber layer. The DoE showed that P3HT:PCBM layers with appropriate optical properties to be applied in OSCs are fabricated with a PS stirred at 53.5 degrees C for 18 h, and post-deposition TT below to 150 degrees C. These results were corroborated with X-ray diffraction, microscope optical images, and electrical and optical responses of manufactured solar cells.

Automated summary

Organic solar cells are cost-effective and flexible, but small deviations in manufacturing variables can affect their performance. This study systematically examined the effects of precursor solution processing and post-deposition thermal treatment on the optical properties of P3HT:PCBM absorber-layer. The results showed that temperature had the greatest influence on material properties, while stirring time alone was least significant. However, the interaction between stirring time and high temperature promoted structural disorder, leading to degradation of the absorber layer. Design of Experiments indicated that P3HT:PCBM layers with suitable optical properties for OSCs were fabricated with a precursor solution stirred at 53.5 degrees C for 18 hours and post-deposition thermal treatment below 150 degrees C. These findings were supported by X-ray diffraction, microscope optical images, and electrical and optical responses of manufactured solar cells.