Multiple functionalities of highly conductive and flexible photo- and thermal-responsive colorimetric cellulose films

Photochromic materials have attracted considerable interest because of their ability to undergo reversible color switching. We report highly conductive and flexible spiropyran-embedded cellulose films with multiple optical and electrical functionalities, showing negative photo- and thermochromism. Combining silver nanowires and conductive polymer with cellulose/spiropyran films achieves a very low sheet resistance of 6.7 ohm/sq. The optimized films show outstanding mechanical stability with negligible electrical loss (resistance change < 2%) after 1000 bending cycles. The photo- and thermal-responsive conductive cellulose/spiropyran films can be used to directly visualize information and as flexible heating devices, pressure-responsive sensors, and colorimetric thermometers with high device performance.