Voltage-Tunable Dual Image of Electrostatic Force-Assisted Dispensing Printed, Tungsten Trioxide-Based Electrochromic Devices with a Symmetric Configuration

Abstract

Electrostatic force-assisted dispensing (EFAD)printed tungsten trioxide (WO 3 )-based electrochromic devices (ECDs) displaying a dual image depending on the applied voltage are demonstrated. We first print WO 3 via EFAD printing, in which the width of the printed lines can be tuned by adjusting the printing speed. The performance of the ECDs is characterized while varying the thickness of the printed WO 3 film. It is determined that ∼550 nm thick WO 3 is the optimal film considering maximum transmittance contrast (ΔT max ), device dynamic responses, efficiency, and long-term coloration/bleaching cyclic stability. More significantly, the coloration of the devices in this work can alternatively appear due to the use of electrolyte-soluble anodic species (here, dimethyl ferrocene, dmFc), for which WO 3 films should be deposited on both electrodes and a part of the electrodes should be exposed to the electrolyte for the oxidation of dmFc. To take advantage of such features of the devices, we successfully demonstrate EFAD-printed, flexible WO 3 ECDs alternately displaying a dual image, which is expected to have high potential as a functional component of printed electronics.

Physical Simulation Model of WO3 Electrochromic Films Based on Continuous Electron-Transfer Kinetics and Experimental Verification

“…This is because the coloring potential (−0.4 V) only reaches the reduction potential of the electron transfer step 1 (−0.32 V) but is higher than the reduction potential of electron transfer step 2 (−0.55 V), causing the deviation in the dynamics of the continuous electron-transfer process. This also explains why the traditional single-electron-transfer electrochromic simulation model is reliable at a low applied bias but deviates from the experiments at a high bias. , In fact, electrochromic devices usually require a large bias (<−0.9 V vs Ag/AgCl) to yield a good performance. − …”

Functional Ion Gels: Versatile Electrolyte Platforms for Electrochemical Applications

“…This process was referred to as a “design-it-yourself (DIY)” protocol, which allows users to create a variety of ECDs to deliver their own messages. It is noted that patterned ECDs were demonstrated by combining photolithography and digital printing such as electrostatic-force assisted dispensing printing , by taking advantage of the compatibility of ion gels with solution processing.…”

Strategy for Selective Printing of Gate Insulators Customized for Practical Application in Organic Integrated Devices

“…Therefore, the ink which ejected from the nozzle tip was subjected to a constant pulling force due to the external electrostatic field, unlike in the case of conventional dispensing. , Consequently, the droplet formed on the nozzle tip almost maintained a constant shape, and the deposited line patterns possessed a constant width even during long durations of printing. Additionally, the electrostatic field induced an electric charge in the liquid, thereby generating an electrostatic force of attraction with the substrate to form an uncut and densely packed thin film. ,, …”

“…Additionally, the electrostatic field induced an electric charge in the liquid, thereby generating an electrostatic force of attraction with the substrate to form an uncut and densely packed thin film. 25,26,29 Based on such analyses, electrostatic-force-assisted dispensing was selected for preparing the GI layers that could exhibit uniform and superior insulating properties. For the fabrication of EHD-printed GI layers, 7 wt% of GI ink was prepared for each material.…”