Switching of Electron and Ion Conductions by Reversible H₂O Sorption in n-Type Organic Semiconductors

Polar H2O molecules generally act as trapping sites and suppress the electron mobility of n-type organic semiconductors, making chemical design of H2O-tolerant and responsive n-type semiconductors an important step toward multifunctional electron–ion coupling devices. The introduction of effective electrostatic interactions between potassium ions (K+) and carboxylate (−COO–) anions into the electron-transporting naphthalenediimide π-framework enables the design of high-performance H2O-tolerant n-type semiconductors with a reversible H2O adsorption–desorption ability, where the electron mobility and K+ ionic conductivity were coupled with the reversible H2O sorption behavior. The reversible H2O adsorption into the crystals enhanced the electron mobility from 0.04 to 0.28 cm2 V–1 s–1, whereas the K+ ionic conductivity decreased from 3.4 × 10–5 to 4.7 × 10–7 S cm–1. Because this reversible electron–ion conducting switch is responsive to H2O sorption behavior, it is a strong candidate for H2O gating carrier transport systems.