Unlocking functional potentials: Nanofibril networks in organic semiconductors

Organic semiconductors, including π-conjugated polymers and small molecules, find potential applications across a wide range of scenarios, including organic field-effect transistors (OFETs), organic photovoltaics (OPVs), organic photodetectors (OPDs), and more. A crucial factor in optimizing the performance of these devices is the charge carrier transport properties, which is closely related with the structural organization of organic semiconductors at various length scales. The fibrillar texture, typically comprising structures with tens of nanometers in width and extending into microscale in length, is an important morphology linked to high-performance outcomes. These fibrils often exhibit semi-ordered domain and are well-dispersed within amorphous matrices, enabling efficient charge transport pathways. This review summarizes the origins and advantages of optoelectronic fibrillar thin films, elucidating their role in enhancing device performance. We further highlight how fibrillar structures not only boost performance in OFETs, OPVs and OPDs, but also offer unique advantages for practical device applications, such as stretchable electronics and polarization-sensitive detectors. Finally, we identify key challenges and propose future research directions, including the transition from solution assembly into fibrils, cooperative interactions with amorphous domains, advanced structural characterization, scalability and industrial potential, and emerging functionalities. This review aims to advance the understanding of fibrillar morphology, positioning it as a key factor in achieving better performance in the field of organic semiconductors.