Air‐stable Perylene Diimide Trimer Material for n‐type Organic Electrochemical Transistors

Abstract A new method is reported to make air‐stable n‐type organic mixed ionic‐electronic conductor (OMIEC) films for organic electrochemical transistors (OECTs) using a solution‐processable small molecule helical perylene diimide trimer, hPDI[3]‐C 11 . Alkyl side chains are attached to the conjugated core for processability and film making, which are then cleaved via thermal annealing. After the sidechains are removed, the hPDI[3] film becomes less hydrophobic, more ordered, and has a deeper lowest unoccupied molecular orbital (LUMO). These features provide improved ionic transport, greater electronic mobility, and increased stability in air and in aqueous solution. Subsequently, hPDI[3]‐H is used as the active material in OECTs and a device with a transconductance of 44 mS, volumetric capacitance of ≈250 F cm −3 , µC * value of 1 F cm −1 V −1 s −1 , and excellent stability (> 5 weeks) is demonstrated. As proof of their practical applications, a hPDI[3]‐H‐based OECTs as a glucose sensor and electrochemical inverter is utilized. The approach of side chain removal after film formation charts a path to a wide range of molecular semiconductors to be used as stable, mixed ionic‐electronic conductors.