Naphthalene diimide-based n-type small molecule organic mixed conductors for accumulation mode organic electrochemical transistors.

Organic mixed ionic-electronic conductors (OMIECs), which transport both ionic and electronic charges, development are important for progressing bioelectronic and energy storage devices. The p-type OMIECs are extensively investigated and used in various applications, whereas the n-type ones lag far behind due to their moisture and air instability. Here, we report the synthesis of the novel n-type naphthalene diimide (NDI)-based small-molecule OMIECs for organic electrochemical transistors (OECTs). The electro-active NDI molecule with the linear ethylene glycol side chains is a promising candidate for n-type channel material to obtain accumulation mode OECTs. This NDI-based small-molecule OMIEC, gNDI-Br 2 , demonstrates ion permeability due to the attachment of the glycol side chains with optimized ionic-electronic conductions. OECT devices with gNDI-Br 2 channel material displays excellent performance in water and ambient stability. OECTs fabricated with two different concentrations, 50 mg mL -1 and 100 mg mL -1 of gNDI-Br 2 demonstrate a transconductance value of 344 ± 19.7 μS and 814 ± 124.2 μS with the mobility capacitance product ( μC *) of 0.13 ± 0.03 F cm -1 V -1 s -1 and 0.23 ± 0.04 F cm -1 V -1 s -1 , respectively. These results demonstrate the n-type OMIEC behaviour of the NDI-based small-molecule and its applicability as an OECT channel material.