Flanking-Group Engineering Unlocks Emerging Functionalities in Diketopyrrolopyrrole Semiconductors.

Diketopyrrolopyrrole (DPP) is a cornerstone building block in high-performance organic semiconductors, valued for its strong π-conjugation, chemical robustness, and tunable optoelectronic characteristics. Conventional DPP synthesis relies on aromatic nitrile precursors, establishing a design paradigm in which flanking aromatic units govern energy levels, molecular packing, and charge transport. Although systematic variation of these flanking groups has enabled substantial performance gains, this strategy inherently constrains structural diversity and limits functional adaptability, particularly for emerging technologies requiring flexibility, biointegration, and multimodal responsiveness. Recent advances move beyond this conventional framework by reengineering DPP flanking architectures and molecular topologies. In addition to enabling new functionalities in established material systems, unconventional design strategies, such as naphthalene-based motifs, vinyl linkages, and fused DPP backbones, have been developed to reshape electronic coupling and intermolecular interactions. These approaches expand DPP functionality beyond traditional transistor and photovoltaic roles toward flexible electronics, intelligent skins, and (bio)sensing platforms. By establishing flanking-group engineering as a unifying design paradigm, this review provides a coherent structure-property-application framework for DPP-based semiconductors, offering generalizable guidelines for the development of next-generation multifunctional organic electronics.