Morphological Optimization of the Active Layer from Film Formation Kinetics in Organic Solar Cells

A deep understanding of the structural evolution is critical for the precise morphological optimization of the active layer in organic solar cells. This perspective systematically reviews the kinetic mechanisms of film formation and emphasizes that regulating processing parameters, such as deposition temperature, processing solvent, and additives, can effectively govern crystallization and phase separation during layer deposition. Advanced <i>in situ</i> characterization techniques are highlighted as indispensable tools for real-time decoding of these coupled kinetic pathways. We also summarize these techniques, covering their principles, detectable structural information, and inherent limitations and constraints, thereby guiding the selection of appropriate <i>in situ</i> tools. Finally, we outline the key challenges in the field and provide insights into future research aimed at advancing device performance through targeted morphological control.