A new scaling strategy for Electrochromic (EC) smart windows.

In a recent article published in the magazine ACS Energy Messagesthe researchers discussed the development of fast electric switch Hardware driven by possible gradation.

Stady: Gradient-driven fast switching electrical device. Image Credit: JP WALLET / Shutterstock.com


The dangerous consequences of global warming require immediate efforts to conserve energy and reduce emissions. Electrical devices (EC), which can enhance energy efficiency by changing spectral properties dynamically and reduce energy consumption, have received great attention in terms of smart windows for energy-efficient buildings.

Conventional EC devices require an external bias to deliver voltage or current, which results in increased power consumption, nullifying energy savings, and impeding the independent and long-term operation of EC devices. Now, several energy harvesting technologies such as photovoltaic devices and frictional nanogenerators have been linked to EC devices to create autonomous EC device systems to address this problem.

In general, it appears that no technology can achieve both universality and high performance in the overall chassis design of a self-powered EC device. As a result, a new technology is required to build reversible, fast, self-switching EC devices with a simpler configuration. The electromotive force that allows the battery to transfer electrical energy to an external circuit is known as the standard free energy change corresponding to the reaction of the cell, which can be measured by finding the electromotive force.

About the study

In this study, the authors present a potential gradient technique for developing a fast-charging as well as self-rechargeable EC system. A potential difference between zinc (Zn) and Prussian blue (PB) was used in this technique to convert PB to Prussian white (PW) in 1.0 s, while etched carbon paper (ECP) was used to oxidize PW to its original state in 2.2 seconds. This strategy has also been used for other high-performance EC systems, such as Zn || PEDOT || ECP, Zn || WO3|| ECP and Zn || PB || ZnHCF and Al || PB || ECP. 25 cm prototype2 The EC window was constructed using poly(vinyl alcohol) (PVA) and KCl gel electrolyte to discuss the potential application of large-scale windows.

The researchers discussed the development of a new fast, self-switching EC system with fast response time, large optical contrast, and high reversibility using an effective potential gradient construction technique between a PB electrode, a positive ECP electrode, and a Zn negative electrode. By replacing EC or positive/negative electrodes with different materials, the universality of this promising gradient technology was examined.

The team demonstrated the potential applications of the proposed large-area smart windows corresponding to a fast self-switching EC system by assembling 5 x 5 cm2 and 10 x 10 cm2 Prototype devices.


The contact of PB to Zn increased the permeability of the stomach 25 cm2 A window of 2% to 66% in 28 seconds, while reversing the PW connection to the ECP dropped it from 73% to 9% in 30 seconds. The discharge capacity of the Zn/PB battery was 23.3 mAh-2 As determined by galvanic discharge at 0.1 mA cm-2. In PB and PW, the Fe(III)/Fe(II) pair was responsible for the discharge plateau at 1.2 eV.

After discharging, the open circuit voltage of the PW can approach 1.8V when connected to the ECP during stand-up operation, which is indicative of the self-charging process. At 700 nm, the difference in transmittance between the colored and bleached states of this system was 68.1%. When the PB electrode has an area of ​​2 x 4 cm2 Connected to Zn electrodes, the transmittance increased by 61.3% in just 1.0 s, while it decreased from 93% to 31.7% in 2.2 s when switching to ECP electrodes, which showed rapid staining and bleaching processes. meDr/meJ The severity ratio for ECP was 1.105, which indicates that ECP has many defects.


In conclusion, this study demonstrated that the proposed EC system eliminates the need for external power and satisfies the demand for easy-to-reversible, simple and fast-switching EC devices. A potential gradient strategy is proposed to achieve a fast self-charging and non-rechargeable EC system without any external supply, as the potential difference between PB and Zn is generated to reduce PB to PW within 1.0 s, and PW can be oxidized to its original state in 2.2 s due to the susceptibility to The strong oxidation of ECP derived from the carbonyl/hydroxyl carbon conversion.

The authors report that the new potential gradient technology offers new insight into the development of a fast, self-switching EC device with promising applications in energy storage and conservation.

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Luo, Y., Jin, H., Lu, Y., A potential gradient-driven fast-switching electrical device. ACS Energy Letters 7 1880-1887 (2022). https://pubs.acs.org/doi/10.1021/acsenergylett.2c00452

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