Raman spectroelectrochemical study on the effect of solvent processing on the active layer morphology of polymer solar cells

Solution processing is an important advantage for polymer solar cells (PSCs). To study the effect of solvent processing on the active layer morphology and device performance of polymer solar cells, the relationship be-tween the active layer morphology and the device performance of a classical photovoltaic system (P3HT:PCBM) was studied by using steady-state absorption spectroscopy, atomic force microscopy, Raman spectroelec-trochemical and current-voltage measurements, etc. The results showed that P3HT polymer was mainly disor-dered aggregation feature in the P3HT:PCBM prepared from low-boiling-point solvent (CS2), which is bad for charge transport, leading to a low photoelectric conversion efficiency. In contrary, high-boiling-point solvent (o- DCB) processed active layer could be self-organized during the film-forming process, and P3HT ordered phase showed a good spatial distribution in the active layer, which is conducive to charge generation and transport, as well as reduction the charge recombination probability. Thus, it has higher power conversion efficiency.