A Planar Electrochromic Device using WO₃ Nanoparticles and a Modified Paper-Based Electrolyte

Electrochromic devices are increasing its interest in the last decades due to the wide range of applications, from smart windows to biosensors or from smart labels to super-capacitors. So, the development of simple and cost-effective production technologies based on solution process and mask less approach is of great interest. In this work, a new planar and flexible electrochromic device based on tungsten oxide (WO3) nanoparticles with a paper-based modified electrolyte was successfully produced, using a CO2 laser technology for electrodes patterning and hydrothermal synthesis for the nanoparticles production. The devices were fabricated with a paper pad inserted in the sensor area for hydration on time of usage, thus replacing the electrolyte material of a typical electrochromic structure with a multi-layer stack, eliminating leakage problems, easy integration with other devices and enhancing the shelf life of the devices to several months. The produced device presents a low power consumption of only 2.86 μA·cm−2, with a deep blue color and an initial charge modulation of 11.5