Manipulating Film Morphology of All‐Polymer Solar Cells by Incorporating Polymer Compatibilizer

Morphology control in multiblend all‐polymer solar cells is crucial for improving charge generation processes. Herein, it is demonstrated that the film morphology of the light‐harvesting layer of all‐polymer solar cells can be manipulated by incorporating a copolymer as the compatibilizer. Through in situ grazing‐incidence wide‐angle X‐ray scattering characterization, the insights of the crystallization kinetics of the polymer blends from solution to thin‐film state are provided. Of particular importance is that by kinetic and thermodynamic control of the film‐processing conditions, an optimal morphology with appropriate nanoscale fibrillar structure in a well‐mixed matrix is achieved. These findings indicate that the interplay between the crystalline regions and weakly/noncrystalline regions that are induced by the compatibilizer polymer plays a critical role in determining the morphology in multicomponent blend all‐polymer solar cells.