Hole Mobility Enhancement in Benzo[1,2-b:4,5-b']Dithiophene-Based Conjugated Polymer Transistors through Directional Alignment, Perovskite Functionalization and Solid-State Electrolyte Gating

Tunability in electronic and optical properties has been intensively explored for developing conjugated polymers and their applications in organic and perovskite-based electronics. Particularly, the charge carrier mobility of conjugated polymer semiconductors has been deemed to be a vital figure-of-merit for achieving high-performance organic field-effect transistors (OFETs). In this study, the systematic hole carrier mobility improvement of benzo[1,2-b:4,5-b']dithiophene-based conjugated polymer in perovskite-functionalized organic transistors is demonstrated. In conventional OFETs with a poly(methyl methacrylate) (PMMA) gate dielectric, improvements in hole mobility of 0.019 cm² V⁻¹ s⁻¹ are measured using an off-center spin-coating technique, which exceeds those of on-center counterparts (0.22 ± 0.07 × 10⁻² cm² V⁻¹ s⁻¹). Furthermore, the mobility drastically increases by adopting solid-state electrolyte gating, corresponding to 2.99 ± 1.03 cm² V⁻¹ s⁻¹ for the control, and the best hole mobility is 8.03 cm² V⁻¹ s⁻¹ (average ≈ 6.94 ± 0.59 cm² V⁻¹ s⁻¹) for perovskite-functionalized OFETs with a high current on/off ratio of >10⁶. The achieved device performance would be attributed to the enhanced film crystallinity and charge carrier density in the hybrid perovskite-functionalized organic transistor channel, resulting from the high-capacitance electrolyte dielectric.