Efficient n‑Type Small-Molecule Mixed Ion-Electron Conductors and Application in Hydrogen Peroxide Sensors

Small-molecule
semiconductors used as the channel of organic electrochemical
transistors (OECTs) have been rarely reported despite their inherent
advantages of well-defined molecular weight, convenient scale-up synthesis,
and good performance reproducibility. Herein, three small molecules
based on perylene diimides are readily prepared for n-type OECTs.
The final molecules show preferred energy levels, tunable backbone
conformation, and high film crystallinity, rendering them good n-type
dopability, favorable volumetric capacities, and substantial electron
mobilities. Consequently, the OECTs afford a record-low threshold
voltage of 0.05 V and a normalized peak transconductance of 4.52 ×
10–2 S cm–1, as well as impressive
long-term cycling stability. Significantly, the OECTs utilized for
hydrogen peroxide sensing are further demonstrated with a detection
limit of 0.75 μM. This work opens the possibility of developing
nonfullerene small molecules as superior n-type OECT materials and
provides important insights for designing high-performance small-molecule
mixed ion-electron conductors for OECTs and (bio)­sensors.