A Hybrid Acceptor-Modulation Strategy: Fluorinated Triple-Acceptor Architecture for Significant Enhancement of Electron Transport in High-Performance Unipolar n-Type Organic Transistors

The development of unipolar n-type semiconducting polymers with electron mobility (mu(e)) over 5 cm(2) V-1 s(-1) remains a massive challenge in organic semiconductors. Diketopyrrolopyrrole (DPP) has proven to be a successful unit for high-performance p-type and ambipolar polymers. However, DPP's moderate electron-accepting capability leads to the shallow frontier molecular orbital (FMO) levels of the resultant polymers and hence limit the mu(e) in unipolar n-type organic transistors. Herein, this issue has been addressed by using a hybrid acceptor-modulation strategy based on DPP-containing fluorinated triple-acceptor architecture, namely DPP-difluorobenzothiadiazole-DPP (DFB). Compared with DFB's non-fluorinated counterpart, DFB features deeper FMO levels and a shape-persistent framework. Therefore, a series of DFB-based polymers demonstrate planar backbones and lowered FMO levels by approximate to 0.10 to 0.25 eV versus that of the control polymer. Intriguingly, all DFB-polymers exhibit excellent unipolar n-type transistor performances. Notably, a full-locked backbone conformation and high crystallinity with crystalline coherence length of 524 angstrom are observed for pDFB-TF, accounting for its high mu(e) of 5.04 cm(2) V-1 s(-1), which is the highest mu(e) value for DPP-based unipolar n-type polymers reported to date. This work demonstrates that the strategy of fluorinated triple-acceptor architecture opens a new path towards high-performance unipolar n-type semiconducting polymers.

Automated summary

In this study, a hybrid acceptor-modulation strategy based on a fluorinated triple-acceptor architecture was used to address the issue of low electron mobility in unipolar n-type organic transistors. The resulting polymers demonstrate high electron mobility and open up a new path towards high-performance unipolar n-type semiconducting polymers.