Benzo/Naphthodifuranone-Based Polymers: Effect of Perpendicular-Extended Main Chain π-Conjugation on Organic Field-Effect Transistor Performances

For polymer semiconductors, the backbone structure plays an essential role in determining their physicochemical properties and charge transport behaviors. In this work, two donor-acceptor-type polymers (P-BDF and P-NDF) based on benzodifuranone (BDF) and naphthodifunarone (NDF) as electron-deficient moieties and indaceno-dithiophene as electron-rich groups are designed, synthesized and, for the first time, applied in organic field-effect transistor. P-BDF and P-NDF differ from their backbone structures while P-BDF has a more planar backbone conformation due to its smaller conjugated core size and P-NDF features a perpendicular-extended main chain structure. As a result, P-BDF polymer exhibits bathochromic optical absorption, deeper molecular orbital energy levels, and more importantly, closer pi-stacking and stronger aggregation in the solid state and thus affords a more promising hole mobility of up to 0.85 cm(2) V-1 s(-1) in OFET devices, while that of the P-NDF-based devices is only 0.55 cm(2) V-1 s(-1). The results suggest the great potential of BDF/NDF-type chromophores in constructing novel organic semiconductors and also indicate that the main chain coplanarity of polymer semiconductors is more essential than the sole extension of pi-conjugations (especially at the perpendicular direction of polymer main chains) for the design of high-performance OFET materials.

Automated summary

In this study, two donor-acceptor-type polymers (P-BDF and P-NDF) based on benzodifuranone (BDF) and naphthodifunarone (NDF) were designed and synthesized with different backbone structures. It was found that the planar backbone conformation of P-BDF led to superior charge transport performance compared to P-NDF. The results suggest that the main chain coplanarity of polymer semiconductors is more essential than the sole extension of pi-conjugations.