Facile fabrication of transparent and stretchable cellulose ionic gel paper for sustainable use in multifunctional sensors and optoelectronic devices

Although transparent paper derived from cellulose has been successfully demonstrated as an inexpensive, renewable and biodegradable substrate used for flexible electronics, the inherently stiff characteristic and intrinsic poor conductivity of the cellulose paper inevitably hinders its application in stretchable electronic devices. Herein, we report a new avenue for construction of highly stretchable, transparent, and ionic conductive cellulose gel paper via glycerol inducing plasticizing and CaCl 2 initiating chelating, a facile casting and drying strategy. The renewable carboxymethyl cellulose is employed for its intrinsically abundant carboxyl groups for crosslinking with Ca 2+ via ionic coordination bonds, benefiting the improvement of various performances. The resultant cellulose ionic gel paper (CIGP) displays high stretchability (tensile strain 320 % and strength 978 kPa at fracture), and transparency (over 90 % in 400 nm to 780 nm wavelength). In addition, the CIGP also has high ionic conductivity (82.78 mS/m), and displays highly reliable, sensitive and wide range strain sensing abilities to various stimuli. Significantly, the transparent CIGP with excellent sensing performances has been successfully integrated into multifunctional sensors and optoelectronic device, showing broad applications in flexible electronics.