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The question of designing high electron mobility polymers by increasing the planarization using diffusive nonbonding heteroatom interactions in diketopyrrolopyrrole polymers is addressed in this. For this, three different diketopyrrolo[3,4‐c]pyrrole (DPP) derivatives with thienyl‐, 2‐pyridinyl‐, and phenyl‐flanked cores are copolymerized with an electron‐rich thiophene unit as well as an electron‐deficient 3,4‐difluorothiophene unit as comonomer to obtain diverse polymeric DPPs which vary systematically in their structures. The crystallinity differs significantly with clear trends on varying both flanking unit and comonomer. The optical gap and energy levels depend more on the nature of the flanking aryl units rather than on fluorination. Additionally, the charge transport properties are compared using different methods to differentiate between interface or orientation effects and bulk charge carrier transport. In organic field effect transistor devices with very high electron as well as hole mobilities (up to 0.6 cm2 V−1 s−1) are obtained and fluorination leads to a more pronounced n‐type nature in all polymers, resulting in ambipolar behavior in otherwise p‐type materials. In contrast, space‐charge limited current measurements show a strong influence of the flanking units only on electron mobilities. Especially, the elegant synthetic strategy of combining pyridyl flanking units with difluorothiophene as the comonomer culminates in a record bulk electron mobility of 4.3 × 10−3 cm2 V−1 s−1 in polymers.

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In thin films of semiconductor polymers, the polymer chains often exhibit distinct orientation with respect to the substrate. The planar π-face of the backbone typically orients either in an edge-on or face-on manner. Generally, an edge-on alignment is thought to be favorable for transport in thin film transistors, whereas face-on alignment is considered to improve vertical transport as desired in solar cells. However, molecular orientation is among the very few parameters that usually cannot be controlled when tailoring new semiconducting polymers. Here we show for an important class of semiconducting polymer that both the mode of orientation as well as the degree of alignment can be well-controlled by exploiting diffusive noncovalent interactions along the backbone. Studying polydiketopyrrolopyrroles (PDPPs) as a case study, by strategically varying chemical structure, we demonstrate systematic variation in molecular orientation with degree of chain planarization resulting from different degrees of diffusive noncovalent interactions. This observation opens the possibility of controlling and optimizing the orientation of semiconducting polymer chains in thin films by rational design. We anticipate our findings to open the door to new high-performance organic semiconductors with the additional benefit of tailored orientation that fits the desired application.