Manufacturing cost is a major concern for electrochromic devices (ECDs) applications in smart windows for energy saving and low-carbon economy. Fully printing instead of vacuum-based chemical vapor deposition (CVD) process...

such as bendable touch screen displays, [1] organic light-emitting diodes (OLEDs), [2] organic photovoltaics (OPVs) [3] and electrochromic devices (ECDs). [4] Among the devices mentioned above, flexible electrochromic devices (FECDs) hold great promise for versatile applications owing to the ability to change optical properties reversibly in response to applied voltages and can be attached to the curved surface due to their flexibility. [5] However, the main challenge presently for scaling up FECDs is the nonuniform coloration from the edge to the center of a large-area device during operation because of the undesirable voltage variation across the device caused by high sheet resistance of electrode material, which is mainly PET-ITO. [6] As the most widely used transparent conductive material, indium tin oxide (ITO) stands out for its high optical transmittance and chemical stability. [7] Despite the matured large-area ITO sputtering process on flexible substrates such as polyethylene terephthalate (PET) or polyimide (PI), brittleness and relatively high sheet resistance are still the two drawbacks of flexible ITO substrates which cannot be solved simultaneously because the sheet resistance of ITO film directly relates to its thickness.In order to overcome the inherent limitations of ITO-based electrodes, several alternatives have been developed as FTEs such as conducting polymers, [8] carbon materials, [5a,9] metallic nanowires, and nanostructures. [10] Notably, silver nanowire (Ag NW) has been widely studied as the electrode material for the fabrication of FECDs owing to its outstanding flexibility and simplicity for scalable processing. [4c] However, the sheet resistances of reported Ag NWs are usually limited in the range of 10 Ω □ −1 , [3a,4c,11] which is not a significant breakthrough in conductivity compared to PET-ITO (typically ≥30 Ω □ −1 without metallic modification), hindering their further applications in large-area FECDs. Considering all the FTE technologies reported so far, metal-mesh is believed to be the only technology that can easily reach a sheet resistance of less than 1 Ω □ −1 by adjusting mesh pitch, line width, and metal thickness. [12] However, owing to the high mobility of silver and the poor electrochemical stability of copper, bare Ag or Cu mesh is practically not suitable as the electrode material for traditional ECDs. [10a,13] Liu et. reported Flexible electrochromic devices (FECDs) hold great promise for energysaving static displays. As the most widely used flexible transparent electrode (FTE) material for FECDs, the indium tin oxide (ITO) coated on polyethylene terephthalate (PET-ITO) suffers from relatively high sheet resistance which can cause nonuniform coloration during the device operation, hindering the development of large-area FECDs. Herein, a hybrid FTE is developed in which an additional copper (Cu) mesh as an embedded current collector layer underneath the ITO film to achieve ultra-low sheet resistance (<0.2 Ω □ −1 ) compared to that of PET-ITO (≈35 Ω □ −1 )...

Electrochromic (EC) smart windows with transparency-tuning capability can provide buildings with effective sun-shading and privacy to occupants at low energy consumption. The essential requirements to EC windows are fast response, dynamic tunability and low-cost. Recent development in all-in-one electrochromic devices (ECDs) which combines electrolyte, electrochromic and ion storage functions in a single gel has the advantage of single layer structure and can be manufactured in large areas at low cost. However, the coloring voltage and time of all-in-one ECDs can be influenced by the viscosity of active gel. By raising the working temperature, the ECD may have faster response time and lower coloring voltage due to reduced gel viscosity. To enable high working temperature, a high conductivity and high transparency metal-mesh heating film was integrated to an EC window glass. The coloring performance of the EC window was investigated at different heating temperatures compared to its room temperature performance. It was found that working at 70 ℃ the coloring efficiency was doubled and the response speed of the device is 5 times faster than that at room temperature. The integrated metal-mesh heating film also brought added benefits such as defog and defrost for car windshield.