Charge Polarity Modulation and Efficient Electron Transport in Quinoid–Donor–Acceptor Polymers by Acceptor Engineering for High-Performance Transistors

Fine-tuning the charge polarity and enhancing electron transport in conjugated polymers are critical for developing high-performance organic field-effect transistors (OFETs). Quinoidal polymers, characterized by planar backbones and deep-lying lowest unoccupied molecular orbital (LUMO) energy levels, offer distinct advantages over their aromatic counterparts but face challenges in achieving reliable electron mobilities exceeding 1 cm² V^–1 s^–1. Herein, we synthesized and characterized a set of novel quinoid–donor–acceptor (Q-D-A) polymers with various acceptor units. Increasing acceptor strength narrowed the band gap, lowered LUMO levels, and shifted charge polarity from unipolar p-type to ambipolar and ultimately to dominant n-type behavior. The electron-to-hole mobility ratio increased from 0 to 40 with electron transport behavior observed in a Q-D-A polymer for the first time. Consequently, the strongest acceptor-based polymer exhibited a planar backbone, small electron effective mass, high crystallinity, and low disorder, resulting in a reliable electron mobility of 1.20 cm² V^–1 s^–1 with decent operational stability. This mobility is a record-high value for quinoidal polymers with reliable electron transport. Our findings offer a viable strategy for tuning charge polarity and improving n-type transport in quinoidal polymers, providing insights into the structure–property relationships essential for advancing high-performance organic electronics.