n-Type Glycolated Imide-Fused Polycyclic Aromatic Hydrocarbons with High Capacity for Liquid/Solid-Electrolyte-based Electrochemical Devices

Currently, n-type small-molecule mixed ionic-electronic conductors remain less explored and their molecular design rules are not mature enough. Herein, two n-type glycolated imide-fused polycyclic aromatic hydrocarbons (IPAHs), d-gdiPDI and t-gdiPDI, are developed to probe the effects of molecular conformation on the electronic, electrochemical, morphological, and coupled ionic-electronic transport properties. It is found that the highly twisted scaffold in d-gdiPDI, compared to the nearly planar one of t-gdiPDI, has a strong positive effect on the charge storage properties and thus the performance of organic electrochemical transistors (OECTs). d-gdiPDI exhibits a volumetric capacitance of 657 F cm−3, obviously outperforming that of t-gdiPDI (261 F cm−3), which is the highest value reported to date for small-molecule OECT materials. Moreover, a high charge-storage capacity of up to 479 F g−1 is observed for d-gdiPDI. Arising from such high ionic-electronic coupling characteristic, d-gdiPDI-based OECTs present a ≈2 × times higher geometry-normalized transconductance (gm,norm) of 105.3 mS cm−1 relative to that of t-gdiPDI counterparts. Significantly, further application of d-gdiPDI in solid-electrolyte OECTs delivers a gm,norm of 142.4 mS cm−1. These findings indicate that IPAHs are very promising candidates for n-type small-molecule OECTs and highlight the superiority of twisting conformation manipulation in materials design toward high-performance electrochemical devices.