Compatibility of cellulose–PEDOT:PSS composites and anions in solid-state organic electrochemical transistors

Abstract

We investigate the effects of water-processable celluloses on the charge-transport properties in the conducting polymer composites and their solid-state organic electrochemical transistors (OECTs). Water-soluble methyl cellulose (MC) and water-dispersible cellulose nanofiber (CNF) are blended with poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) in solution and used as a conductive channel. Both cellulose–PEDOT:PSS composites show fibrillar structures in thin films with respective dimensions of cellulose. The electrical conductivity was increased with 5–10 wt% of cellulose in the composite. The solid-state OECTs show better performance when the ionogel contains 1-ethyl-3-methylimidazolium triflate (EMIM:OTf) compared to the system with the commonly used EMIM bis(trifluoromethyl sulfonyl)imide (EMIM:TFSI). The MC–PEDOT:PSS composite paired with an EMIM:OTf-based ionogel exhibits a high figure-of-merit (μC^⁎) of OECTs of >50 F cm⁻¹ V⁻¹ s⁻¹ and an on-to-off current ratio of >10³. Our results show that cellulose and EMIM:OTf are compatible with PEDOT:PSS and that appropriate materials pairing can improve the properties of PEDOT:PSS-based composites and the performance of their electrochemical devices.