Unraveling the Morphological Evolutions during Solvent Vapor Annealing for Organic Solar Cells Using in situ Resonant Soft X-Ray Scattering

Solvent vapor annealing (SVA) is one of the most effective pre-electrode deposition techniques, which has been applied in many efficient organic solar cells. In current research, we used a customized in situ multimodal system to reveal the dynamics of phase separation inside the bulk-heterojunction thin films during SVA via resonant soft x-ray scattering (RSoXS). Solvent-vapor-induced molecular crystallization is of importance to provide the driving force of the domain generation and evolution processes. However, with the introduction of solvent vapor for a long time, coarsening of the film appeared at the film surface, which led to the deteriorating of the device performances. These results indicated that in situ RSoXS is a quite useful technique to bridge the gap to understand the relationship of film growth mechanisms and device efficiency.