RESUMEN
Electrochromic devices, capable of modulating light transmittance under the influence of an electric field, have garnered significant interest in the field of smart windows and car rearview mirrors. However, the development of high-performance electrochromic devices via large-scale explorations under miscellaneous experimental settings remains challenging and is still an urgent problem to be solved. In this study, we employed a two-step machine learning approach, combining machine learning algorithms such as KNN and XGBoost with the reality of electrochromic devices, to construct a comprehensive evaluation system for electrochromic materials. Utilizing our predictive evaluation system, we successfully screened the preparation conditions for the best-performing device, which was experimentally verified to have a high transmittance modulation amplitude (62.6%) and fast response time (5.7 s/7.1 s) at 70 A/m2. To test its stability, experiments over a long cycle time (1000 cycles) are performed. In this study, we develop an innovative framework for assessing the performance of electrochromic material devices. Our approach effectively filters experimental samples based on their distinct properties, substantially minimizing the expenditure of human and material resources in electrochromic research. Our approach to a mathematical machine learning evaluation framework for device performance has effectively propelled and informed research in electrochromic devices.
RESUMEN
In this report, an ammonium metatungstate (AMT) and ferrous chloride [Fe(II)Cl2] electrochromic liquid (ECL) was synthesized using a hydrothermal method, with D2O used as the solvent instead of H2O. The results show that the use of D2O can improve the stability and performance of ECLs. The hydrogen evolution process in electrochromic devices (ECDs) filled with ECL becomes more difficult, while the material exchange process becomes easier. The ECD exhibits a color modulation amplitude of 58%@680 nm at 2 V. After 500 cycles, the device's performance remains above 95% at a current density of 1.5 mA/cm2. Hydrogen bonds in D2O solutions are expected to exhibit stronger forces compared to those in regular H2O solutions. Therefore, we hypothesize that enhancing the strength of hydrogen bonds in H2O solutions is an effective approach for improving the performance and stability of electrochromic solutions.
RESUMEN
Even though electrochromism has been around for more than 50 years, it still has several issues. Multi-layered films, high manufacturing costs, and a short lifetime are present in existing electrochromic devices. We demonstrate a unique high-performance device with a basic structure and no solid electrochromic sheets in this work. In this device, the electrolyte layer is also avoided. The device uses an electrochromic solution prepared from a mixture of ammonium metatungstate and iron (II) chloride solution as a functional layer with reversible redox properties. The tungstate ions on the electrode surface are reduced when the device is colored, and the Fe2+ on the electrode surface is oxidized on another electrode surface. The generated Fe3+ in the mixed functional layer oxidizes the previously reduced tungstate ions as the device fades. We determined the ΔT (transmittance modulation) and response time among ammonium metatungstate ratios, iron (II) chloride ratios, and driven current density using DOE (design of experiment) trials. Using 0.175 mol/L ammonium metatungstate and 0.30 mol/L iron (II) chloride, a device with outstanding ΔT (more than 57% at 700 nm), a short response time (less than 10 s), and high coloring efficiency (160.04 cm2/C at 700 nm) is demonstrated.
