Ionically Modified Cellulose Nanocrystal Self-Assembled Films with a Mesoporous Twisted Superstructure: Polarizability and Application in Ion-Gated Transistors

Mesoporous structures made of cellulose nanocrystals (CNCs) and their self-assembly into films are of great interest not only due to their abundancy and sustainability but also due to their ease of chemical modification and nanoscale biomimicry capabilities. However, their implementation in (opto)electronic devices requires further understanding on how these self-assembled twisted mesoporous superstructures respond to electrical stimulus. In this regard, this work focuses on the infiltration of solid CNC droplets with three distinct alkali ions (Li+, Na+, and K+) to yield films with improved electrochemical response when compared to pristine ones, while preserving their photonic character. Electrochemical characterization shows capacitances of up to 2.5 μF cm–2 allowing for their integration as solid-state gate electrolytes in amorphous indium–gallium–zinc–oxide transistors, resulting in low operating voltages (<2 V), on/off ratios of up to 6 orders of magnitude, and high saturation mobilities >10 cm2 V–1 s–1. Devices fabricated on Na+ and K+ infiltrated CNC films present the best characteristics, indicating pure capacitive charging of the semiconductor. The insights presented here contribute to applications in solid-state ionics in mesoporous structures or the combination of optically active electrolytes capable of providing unique functionalities in ion-gated transistors and circuitry.