High Optical Contrast of Quartet Dual-Band Electrochromic Device for Energy-Efficient Smart Window

Abstract

A quartet dual-band electrochromic device (ECD) was developed to selectively control the transmittance from the visible to near-infrared wavelengths for the application of an energy-efficient smart window. The new AgNO 3 +TBABr+LiClO 4 (ATL)-based electrolyte was developed to independently control the redox reaction of lithium and silver ions to demonstrate the quartet mode of an ECD. A dual-band ECD with a sandwich structure was assembled using an ATL-based electrolyte, WO 3 electrochromic layer, and antimony-doped tin oxide (ATO) ion storage layer. The employed WO 3 and ATO films were fabricated using a nanoparticle deposition system (NPDS), a novel ecofriendly dry deposition method. Four modes, namely, transparent, warm, cool, and all-block modes, were demonstrated via an independent redox reaction of both lithium and silver ions through the simple control of the applied voltage. In the warm mode, the localized surface plasmon resonance effect was exploited by producing silver nanoparticles upon two-step voltage application. Furthermore, since the high surface roughness of the WO 3 thin film fabricated by NPDS maximized the light scattering effect, 0% transmittance at all wavelengths was observed in the all-block mode. Dual-band ECD showed high optical contrasts of 73% and longterm durability over 1000 cycles with no degradation. Therefore, the possibility of controlling transmittance at the target wavelength was confirmed using a simple device with a simple process, suggesting a new strategy for the design of dual-band smart windows to reduce the energy consumption of buildings.

Electrochromism in Isoreticular Metal–Organic Framework Thin Films with Record High Coloration Efficiency

“…Second, the optical contrast (Δ T ) which measures the degree of color change was quantified for all three thin films (Figures b, S30, and S31). Very high optical contrast (absorption change of up to 2.5 OD and Δ T up to 97%) is consistently obtained for all members of the isoreticular MOF series (measured at characteristic λ of [XDI] 0/•– ), which is among the highest in electrochromic materials. , Meanwhile, the switching time between the bleached state and the colored state (90% of optical contrast) was determined for all thin films (Figures c and S32). Both coloration time and bleaching time are in the range of a few seconds (Figure c), demonstrating their practical feasibility. , Lastly, the electrochromic stability of the isoreticular MOFs was investigated in accelerated reduction and oxidation operation cycles (details in the SI).…”

“…Very high optical contrast (absorption change of up to 2.5 OD and ΔT up to 97%) is consistently obtained for all members of the isoreticular MOF series (measured at characteristic λ of [XDI] 0/•− ), which is among the highest in electrochromic materials. 59,64 Meanwhile, the switching time between the bleached state and the colored state (90% of optical contrast) was determined for all thin films (Figures 5c and S32). Both coloration time and bleaching time are in the range of a few seconds (Figure 5c), demonstrating their practical feasibility.…”

Ultrafast Visible/Near‐Infrared Dual‐Band Selective Optical Switching via Polarization Control in Layered Low‐Symmetry TlSe

“…Since smart windows typically require high transmission contrast, recently reported EC devices have demonstrated high modulation depths, approaching ≈99% at specific wavelengths. [86] However, their operation speeds typically fall in the range of seconds to tens of seconds, [10][11][12][13]85] making them less suitable for high-speed processing of optical information signals. Furthermore, the fabrication of EC devices necessitates the integration of multiple components and most EC layers involve the integration of NIR-active and visible-active components to achieve dual-band modulation, adding complexity to device structure and fabrication.…”

“…[9] Thus, various dual-band devices capable of selectively sensing [2,3,5] and modulating [10][11][12][13] visible-infrared signals have been intensively developed. However, most existing visible-infrared dual-band modulators rely on electrochromic methods that typically operate on timescales of seconds to minutes, [10][11][12][13] which are unsuitable for processing ultrafast optical signals in the GHz-THz frequency range. Furthermore, such devices often require a combination of multiple materials or structural elements for electrical control, leading to increased complexity in integrated systems.…”

“…[3] Furthermore, it introduces novel functionalities in domains such as bio-imaging, [7] food engineering, [8] and computer vision. [9] Thus, various dual-band devices capable of selectively sensing [2,3,5] and modulating [10][11][12][13] visible-infrared signals have been intensively developed. However, most existing visible-infrared dual-band modulators rely on electrochromic methods that typically operate on timescales of seconds to minutes, [10][11][12][13] which are unsuitable for processing ultrafast optical signals in the GHz-THz frequency range.…”