Cellulose-Based Ionogels for Paper Electronics

A new class of biofriendly ionogels produced by gelation of microcellulose thin films with tailored 1-ethyl-3-methylimidazolium methylphosphonate ionic liquids are demonstrated. The cellulose ionogels show promising properties for application in flexible electronics, such as transparency, flexibility, transferability, and high specific capacitances of 5 to 15 mu F cm(-2). They can be laminated onto any substrate such as multilayer-coated paper and act as high capacitance dielectrics for inorganic (spray-coated ZnO and colloidal ZnO nanorods) and organic (poly[3-hexylthiophene], P3HT) electrolyte-gated field-effect transistors (FETs), that operate at very low voltages (<2 V). Field-effect mobilities in ionogel-gated spray-coated ZnO FETs reach 75 cm(2) V-1 s(-1) and a typical increase of mobility with decreasing specific capacitance of the ionogel is observed. Solution-processed, colloidal ZnO nanorods and laminated cellulose ionogels enable the fabrication of the first electrolyte-gated, flexible circuits on paper, which operate at bending radii down to 1.1 mm.