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.