Electron‐Deficient Polycyclic Molecules via Ring Fusion for n‐Type Organic Electrochemical Transistors.

The primary challenge for n‐type small‐molecule organic electrochemical transistors (OECTs) is to improve their electron mobilities and thus the key figure of merit μC*. Nevertheless, few reports in OECTs have specially proposed to address this issue. Herein, we report a 10‐ring‐fused polycyclic π‐system consisting of the core of naphthalene bis‐isatin dimer and the terminal moieties of rhodanine, which features intramolecular noncovalent interactions, high π‐delocalization and strong electron‐deficient characteristics. We find that this extended π‐conjugated system using the ring fusion strategy displays improved electron mobilities up to 0.043 cm2 V−1 s−1 compared to our previously reported small molecule gNR, and thereby leads to a remarkable μC* of 10.3 F cm−1 V−1 s−1 in n‐type OECTs, which is the highest value reported to date for small‐molecule OECTs. This work highlights the importance of π‐conjugation extension in polycyclic‐fused molecules for enhancing the performance of n‐type small‐molecule OECTs. [ABSTRACT FROM AUTHOR]