Fully-printed, paper-based electrochromic devices combined with wireless driving

The rational preparation and design of electrochromic devices (ECDs) are important for practical application, as integrated on packaging products to express key information by means of some intelligent technologies. This work aims to construct homogeneous film of poly (3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) adopting organic solvents doping and gravure printing on a paper substrate. The formed PEDOT:PSS film is shown to provide successfully the desired high conductivity and excellent stability after mild post-treatment via formic acid. The intrinsic reason for the conductivity enhancement is disclosed and correspondingly discussed. The prepared PEDOT:PSS film thus functions in parallel as an electrochromic and electrode layer in assembled ECDs. The two-layer ECD supports a well-defined electrochromic contrast (ΔE* = 20.5), high light absorption property (0.27) at 650 nm, fast switching, and high coloration efficiency (122.8 cm2 C−1) at a low potential of |2.0| V. More importantly, the intelligent operation of the electrochromic unit is launched using wireless driving rather than external working voltage as usual. In application, the driving voltage for ECDs is obtained from the screen-printed induction coil that can be coupled with the magnetic field of near field communication (NFC) equipped in a smartphone. Thus, the wireless driven electrochromic system can be additionally integrated on the package together with a printed ECD in order to display the product pattern under the interaction of the smartphone, improving the interactivity between packaging products and consumers, thereby having high potential for application in the fields of intelligent packaging.