# Fileset

[coordination-nanosheet-based-electrochromic-supercapacitor-with-high-energy-storage-switching-durability-and-long.pdf](https://mdr.nims.go.jp/filesets/c2495f8a-9c8e-43f9-a1ad-4fad98944a61/download)

## Creator

Susmita Roy, Sayan Halder, Sarda Sharma, Karumbaiah N. Chappanda, [Chanchal Chakraborty](https://orcid.org/0000-0002-4829-1367), [Masayoshi Higuchi](https://orcid.org/0000-0001-9877-1134)

## Rights

[Creative Commons BY Attribution 4.0 International](https://creativecommons.org/licenses/by/4.0/)

## Other metadata

[Coordination Nanosheet-Based Electrochromic Supercapacitor with High Energy Storage, Switching Durability, and Long Optical Memory Properties](https://mdr.nims.go.jp/datasets/bb617a95-5992-4f27-b65a-aa7639a42761)

## Fulltext

Coordination Nanosheet-Based Electrochromic Supercapacitor with High Energy Storage, Switching Durability, and Long Optical Memory PropertiesCoordination Nanosheet-Based Electrochromic Supercapacitor withHigh Energy Storage, Switching Durability, and Long OpticalMemory PropertiesSusmita Roy, Sayan Halder, Sarda Sharma, Karumbaiah N. Chappanda, Chanchal Chakraborty,*and Masayoshi Higuchi*Cite This: ACS Appl. Mater. Interfaces 2025, 17, 62499−62509 Read OnlineACCESS Metrics & More Article Recommendations *sı Supporting InformationABSTRACT: Electrochromic (EC) supercapacitors have attractedconsiderable attention as energy storage systems integrated withoptical functions. EC supercapacitors with high-performance andlong-term optical memory properties were successfully fabricatedby a combination of coordination nanosheets (CONASH),composed of Fe(II) ions and a tristerpyridine ligand having anonconjugated linker, and nickel hexacyanoferrate (NiHCF) as aredox-complementary counter material. The EC supercapacitorexhibited EC changes between purple and pale yellow with largeoptical contrast (57.4% at 556 nm), short switching times (1.28/1.69 s), exceptionally high coloration efficiency (619 cm2 C−1),significantly small energy consumption (3.6 mJ/cm2), and excellentEC switching stability of more than 50,000 cycles. The ECsupercapacitor also demonstrated high volumetric capacitance (248.1 F/cm3), energy density (29.37 mW h/cm3), and power density(7.5 W/cm3), maintaining stable performance over 40,000 galvanostatic charge−discharge cycles. Most notably, the device showed adrastically reduced self-discharge property as only 33% optical contrast was returned after 36 h under open-circuit conditions, pavingthe way for an efficient energy storage solution by exploiting the long optical memory of the device. Combining superior ECfunctionality with robust supercapacitive performance, this study offers a foundation for sustainable energy technology.KEYWORDS: metallo-supramolecular polymers, coordination nanosheets, electrochromic supercapacitor, optical memory,redox-complementary counter material■ INTRODUCTIONAs innovative and exceptional energy storage devices, super-capacitors provide excellent power density, quick charge−discharge abilities, and excellent cycling stability, making themhighly promising for various applications.1 However, with theadvent of intelligent electronic goods, multifunctional super-capacitors, including flexible, wearable, self-healing, piezo-electric, etc., are increasingly needed.2,3 In this regard,electrochromic supercapacitors (ECSCs) have gained signifi-cant attention due to their ability to simultaneously changeenergy states with color, allowing visual determination of theenergy state.4,5 Integrating energy storage and electrochromic(EC) functionality into a single device is feasible because theyshare similar mechanisms and device structures.6,7 An essentialcomponent of this integration is the kind of material used forthe electrodes, the substantial voltage window, and the contrastin color between the charged−discharged states.8,9 Electrodematerials should possess both EC and supercapacitiveproperties, such as PEDOT, PANI, PPy, NiO, WO3, TiO2,and V2O5, etc.10−15 However, challenges remain in making ECdevices durable in the narrow electrochemical window ofelectrolytes (0−1.2 V for aqueous and 0−1.8 V for organic)compared to the driving voltage of EC devices, especially insolid-state EC devices.16−21 High driving voltage candecompose the electrolyte solvent, form gaseous byproducts,increase the internal resistance, and reduce cycling stability.22High EC operating voltage also increases energy consumption,especially in large-scale or multiarray systems.23,24 To developlow-threshold voltage EC devices, strategies include enhancingthe electric conductivity of EC materials, increasing the ionicconductivity of the electrolyte, judiciously designing thechemical structure for porous and nanoarchitecture morphol-ogy, and incorporating suitable counter charge-storageReceived: July 13, 2025Revised: October 16, 2025Accepted: October 16, 2025Published: October 29, 2025Research Articlewww.acsami.org© 2025 The Authors. Published byAmerican Chemical Society62499https://doi.org/10.1021/acsami.5c13795ACS Appl. Mater. Interfaces 2025, 17, 62499−62509This article is licensed under CC-BY 4.0Downloaded via NATL INST FOR MATLS SCIENCE (NIMS) on November 19, 2025 at 09:56:34 (UTC).See https://pubs.acs.org/sharingguidelines for options on how to legitimately share published articles.https://pubs.acs.org/action/doSearch?field1=Contrib&text1="Susmita+Roy"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Sayan+Halder"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Sarda+Sharma"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Karumbaiah+N.+Chappanda"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Chanchal+Chakraborty"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Masayoshi+Higuchi"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Masayoshi+Higuchi"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://pubs.acs.org/action/showCitFormats?doi=10.1021/acsami.5c13795&ref=pdfhttps://pubs.acs.org/doi/10.1021/acsami.5c13795?ref=pdfhttps://pubs.acs.org/doi/10.1021/acsami.5c13795?goto=articleMetrics&ref=pdfhttps://pubs.acs.org/doi/10.1021/acsami.5c13795?goto=recommendations&?ref=pdfhttps://pubs.acs.org/doi/10.1021/acsami.5c13795?goto=supporting-info&ref=pdfhttps://pubs.acs.org/doi/10.1021/acsami.5c13795?fig=tgr1&ref=pdfhttps://pubs.acs.org/toc/aamick/17/45?ref=pdfhttps://pubs.acs.org/toc/aamick/17/45?ref=pdfhttps://pubs.acs.org/toc/aamick/17/45?ref=pdfhttps://pubs.acs.org/toc/aamick/17/45?ref=pdfwww.acsami.org?ref=pdfhttps://pubs.acs.org?ref=pdfhttps://pubs.acs.org?ref=pdfhttps://doi.org/10.1021/acsami.5c13795?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://www.acsami.org?ref=pdfhttps://www.acsami.org?ref=pdfhttps://acsopenscience.org/researchers/open-access/https://creativecommons.org/licenses/by/4.0/https://creativecommons.org/licenses/by/4.0/https://creativecommons.org/licenses/by/4.0/electrode layers.25−27 Despite these strategies, achievingultralow threshold voltage and good energy saving and storagecapabilities simultaneously remains challenging, necessitatingnew materials or mechanisms. Moreover, an EC device withhigh EC memory is energy-efficient because it does not needcontinuous power to sustain its new state after switching.28,29To maximize the memory effect in EC devices, the open-circuitoperation must minimize self- or residual or ambient oxidationand reduction. In the oxidative coloring of EC materials, thememory effect is related to the slower discharging of the storedenergy. On the contrary, EC devices with rapid color switchingtimes mainly depend on the swift ion during electrochemicalprocesses and are operated through faster redox transi-tion.30−32 Thus, the faster switching time is related to fastercharging, especially in oxidative EC materials. So, the ECmaterials with high optical memory and faster switching timesare desirable for providing EC devices with faster charging andslower discharging time, ideally to provide a Coulombicefficiency of around 100%. However, creating EC materialsthat combine high memory retention and fast switching speedsis challenging.Metallo-supramolecular polymer (MSP) architectures havebroadened the field of polymer and material science withapplications in catalysis, display technology, molecularconductivity, and biomedicine.33−35 The oxidation state ofthe metal ion, and consequently the band structure, can bealtered by applying an electrochemical potential, enablingdiverse optical and spectro-electrochemical applications.31,36MSPs and metal−organic frameworks (MOFs) are bothcoordination polymers, but they differ in their structuraldimensionality, crystallinity, porosity, and nature of theircharge-transport pathways. MOFs are highly ordered porousstructures with permanent porosity and high crystallinity, whileMSPs have amorphous structures, mechanical flexibility, anduniform film processability, which are advantageous for thin-film technology. Generally, the electrochromism of MSPs isdriven by metal-to-ligand charge transfer (MLCT), and redoxswitching of the metal center alters the MLCT band, resultingin fast and reversible optical modulation. On the other hand,the EC activity of MOFs is usually derived from redox-activelinkers or metal nodes.37The 2D coordination nanosheets (CONASHs) are a specialclass of MSP that can be synthesized by coordination betweenorganic ligands and metal cations through bottom-upinterfacial complexation.38,39 Depending on the choice ofmetal ions and conjugation in ligands, the electricalconductivity of CONASHs can be tuned for high conductivity(10−3−103 S/cm) due to π−d conjugation with a conjugatedorganic ligand or very low conductivity (<10−10 S/cm)utilizing the lack of planarity in the nonconjugated ligand.38,40Exploiting the electronic and redox behaviors, CONASHs areused in photoactivity, electrocatalysis, trans-metalation, elec-trochromism, etc.39,41,42 In recent times, a few Fe(II) or Co(II)containing CONASHs have been reported as excellent ECmaterials for electrochromism, focusing on the color fastnessby utilizing the advantages of the nanosheet structure andconjugated ligand environment in CONASHs.39,41−48 Toconverge the high optical memory with faster switching time,we have introduced nonconjugated ligands in Fe(II)- orCo(II)-based CONASHs.29,49Conventionally, the redox mechanism of EC devices relieson the movement of a single type of cation or anion during thecoloring or bleaching process. This is akin to the “rockingchair” model in energy storage devices.50 The mechanisticsimilarity of EC and battery-type energy storage made MSPspopular as indicative electrochromic energy storage devices(ECESD), as they could direct the energy status by their real-time color hue.19,28,32,51−55 However, CONASHs are notexplored as much as ECESD despite their structural anddimensional superiority in the MSP category.48 On a fewoccasions, Higuchi et al. reported Fe(II)- and phenanthroline-based CONASH for ECESD with a red-to-colorless ECtransition and high capacitive behavior.45,55 In another study,Cong et al. reported a dual-redox-active CONASH incorporat-ing a triphenylamine and phenanthroline−Fe(II) complexwhere dual-redox centers provided mutual Faradaic contribu-tions, synergistically enhancing both EC and pseudocapacitiveenergy storage performances.56 Additionally, Zhuang et al.demonstrated ultrathin CONASH for applying miniaturizedflexible microsupercapacitors.57 Interestingly, all reportedECESD applications focused on fully conjugated ligand-basedCONASH. However, the effect of nonconjugation withinCONASH remains unexplored to date. Yet, nonconjugation inligands can slow down the electron movement and restrict theelectron hopping both in-plane and interplane, reducing theself-reduction tendency of the metal centers to improve thedischarge times in availing the highest Coulombic efficiencyduring energy storage applications. Therefore, it is crucial tostudy the effect of nonconjugation on the ECESD performancein CONASH.In our present work, we have fabricated an ECESD byassembling a nonconjugated ligand-based CONASH (Fe-3TPY) as anode and nickel hexacyanoferrate (NiHCF) asredox-complementary cathode to demonstrate the synergisticeffects of Li+ ion insertion/extraction at the cathode and ClO4−doping/dedoping at the anode while using LiClO4 aselectrolyte. The nonconjugated linker decouples electroniccommunication between metal centers, suppressing electrontransport and self-discharge while improving optical memoryretention. It also minimizes π−π stacking, enabling flexible, lowcrystallinity, and crack-free nanosheets formation. Thus, itstrategically enhances the redox site localization, film quality,electrochemical stability, and memory performance. Again,redox-active transparent complementary electrode-based ECdual-ion capacitors have garnered significant attention as theyrely on the participation of both cations and anions from theelectrolyte between the two electrodes, resulting in excellentEC performance.28 A key advantage is that the complementaryelectrode can reduce the overall operating voltage windowwhile enhancing the devices’ coloration efficiency, specificcapacity, and stability. The fabricated ECESD showcasednotable EC performance in low-voltage window to change thecolor from pristine pink to pale yellow during EC behaviorwith a high optical contrast (ΔT) of 57.4% at 556 nm and fastEC switching times of 1.28 s for bleaching and 1.69 s forcoloration, high coloration efficiency, and ultrahigh ECstability over 50,000 EC cycles. Utilizing the nonconjugatedlinkers in Fe-3TPY, the ECESD showed very high opticalmemory, retaining 33.3% of its optical contrast even after 36 h.The dual-ion-based ECESD also exhibited a high volumetriccapacitance of 248.1 F/cm3 at 1 A/cm3 with a slight IR drop of0.15 V. It demonstrated high energy and power densities of34.45 mW h/cm3 and 7.5 W/cm3, respectively, with 88%retention of the initial capacitance after 40,000 GCD cycles.Notably, volumetric capacitance is more relevant to evaluate acompact and thin-film device’s energy storage performance.ACS Applied Materials & Interfaces www.acsami.org Research Articlehttps://doi.org/10.1021/acsami.5c13795ACS Appl. Mater. Interfaces 2025, 17, 62499−6250962500www.acsami.org?ref=pdfhttps://doi.org/10.1021/acsami.5c13795?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-asSince the active material mass in nanoscale-level films orcoatings is extremely small, areal capacitance may notadequately reflect device performance. In contrast, changes inthe film thickness at a given surface area may significantly affectthe volumetric capacitance.58 In general, attaining both the ECand energy storage properties in a single system is challenging.This is because superior EC properties, such as highercoloration efficiency and faster switching time, tend to berealized with low charge densities, whereas better energystorage requires higher charge densities.59,60 To overcome thiscontradiction, we introduced the CONASH architecture toachieve superior EC properties at high charge densities. Thisarchitecture provides a large electroactive surface area forimproved electric double layer capacitance and a short iondiffusion path, enabling both charge storage and rapid ECswitching to coexist in ECESDs. Furthermore, the use ofNiHCF as a thin, redox-active complementary counterelectrode (CE) can improve charge-storage and super-capacitive properties. Furthermore, the ECESD demonstratedlow energy consumption during electrochromism, even lowerthan that of conventional display technologies (LCD, OLED,etc.). The ECESD design and corresponding amelioratedproperties of Fe-3TPY in this report offer a fresh notion anddirection for creating a high-performance indicative ECESD.■ EXPERIMENTAL SECTIONMaterials and Instrumentation. All reagents in this study werereagent grade and were employed without further purification. Thereaction solvents were extrapure dichloromethane (DCM) andethanol (EtOH). Spectrochemically pure acetonitrile (ACN) wasemployed for cyclic voltammetry (CV), device fabrication, andspectroscopic analyses. S D Fine-Chem Limited supplied reagentgrade ACN, DCM, EtOH, and acetic acid (AA). Specifically, 4′,4‴′-(1,4-phenylene)-bis(2,2′:6′,2″-terpyridine), iron(II)-acetate, 4′-chloro-2′,2:6′,2″-terpyridine, LiClO4, and Fe(BF4)2·6H2O wereacquired from Sigma-Aldrich. Tetra-n-butylammonium perchlorate(TBAP), propylene carbonate (PC), and poly(methyl methacrylate)(PMMA) were sourced from TCI Chemicals (India) Pvt. Ltd.Furthermore, 2-(hydroxymethyl)-2-methylpropane-1,3-diol and pow-dered KOH were obtained from Sisco Research Laboratories Pvt. Ltd.(SRL)-India. ITO-coated glass slides with a resistivity of approx-imately 20 Ω and transmittance exceeding 90% were procured fromShilpa Enterprise, India. Millipore Milli-Q water with a resistivity of18 MΩ cm was employed as needed. Water-based nickelhexacyanoferrate (w-NiHCF) was obtained from Cica-Reagent fromKanto-chemical Co., Inc. and used further for film preparation afterdilution with DI water. Synthesis of (4′,4‴′-((2-(((2,2′:6′,2″-terpyridin)-4′-yloxy)-methyl)-2-methylpropane-1,3-diyl)bis(oxy))di-2,2′:6′,2″-terpyridine) (3TPY), as shown in Scheme S1a inSupporting Information (SI), was conducted following our previouslyreported procedure.29 The details of the synthesis of Fe-3TPY filmgrown through interfacial bilayer polymerization using 3TPY ligand inDCM solution and Fe(BF4)2·6H2O in water and the collectionprocedure of the film in ITO are provided in our previously reportedprocedure.29 A schematic of the synthesis and collection of the Fe-3TPY film is mentioned in Scheme S1b in the SupportingInformation.Electrochemical measurements were performed by using an ALS/CHI electrochemical workstation (Model 612B, CH Instruments,Inc.) with a two-electrode system. An integrated Ocean Opticsmodular spectrometer was connected to the electrochemical analyzerfor monitoring the optical spectral behavior of the EC device uponpotential application. A FEI, Apreo SEM instrument with a 30 kVoperating voltage was used for field emission scanning electronmicroscopy (FESEM) to determine the film morphology. The filmsurface was gold-coated by sputtering with gold for 30 s to reduce thesurface potential. The X-ray photoelectron spectral (XPS) study wasconducted using a Thermo Scientific Multilab 2000 with AlKαradiation (1486.6 eV) operated at 15 kV and 10 mA (150 W). All thebinding energies are with reference to C 1s at 284.85 eV. To checkthe powder X-ray diffraction (PXRD) pattern, CONASH’s flakes fromEtOH were dropped on a Kapton holder, dried at 55 °C overnight,and subjected to the Rigaku MiniFlex XRD instrument.Fabrication of the Hybrid ECESD. In our present study, Fe-3TPY films were directly deposited on ITO glass substrates. Crackedor uneven regions were carefully removed to obtain a uniform filmarea. However, the NiHCF-coated electrode was obtained by spin-coating an aqueous-NiHCF solution at 1200 rpm on the conductiveside of ITOs. NiHCF-coated ITOs were oven-dried at 70 °Covernight, whereas the Fe-3TPY-coated films were air-dried first andthen oven-dried at 70 °C for 2 h. The quasi-solid Li-ion-based gel-electrolyte was prepared with 0.9 g LiClO4 in 21 mL ACN and 6 mLPC, followed by adding 2.1 g PMMA. The mixture was stirred atroom temperature for 8 h to become a transparent viscous state. Thepoint to be mentioned is that the gel-electrolyte bottle was tightlysealed after each use and stored in a desiccator with low humidity.Finally, the dried film-coated ITOs were sandwiched with the gelelectrolyte and kept at room temperature for drying before use.■ RESULTS AND DISCUSSIONSynthesis and General Characterizations. The flexiblenonconjugated ligand 3TPY was synthesized according to ourpreviously reported protocol.29 This included the reactionbetween 2-(hydroxymethyl)-2-methylpropane-1,3-diol and 4′-chloro-2,2′:6′,2″-terpyridine in the KOH base in the presenceof anhydrous DMSO, as represented in Scheme S1a (SI). Thesynthesized 3TPY was thoroughly characterized by NMR andmass spectroscopy, with detailed results provided in ourprevious literature.29,49 Furthermore, as illustrated in SchemeS1b, the synthesis of Fe-3TPY nanosheets was carried outunder static conditions at the interface of 15 mL DCMcontaining 0.1 mM of 3TPY and 15 mL water containing 50mM of Fe(BF4)2·6H2O. The formation mechanism of the Fe-3TPY film relies on the complexation between the TPY unitsof adjacent ligands, facilitated by the introduction of suitableFe2+ ions diffusing from the aqueous subphase.38,61 Aspreviously discussed, to control the film’s thickness and colorintensity, the reaction parameters, such as the concentration ofmetal and the duration of layering in the reaction setup, can beadjusted.46 Although other in situ polymerization methods,such as electrochemical deposition, exist, only interfacialpolymerization allows the formation of two-dimensionalCONASHs. DCM and water were chosen as the solventbecause they are immiscible. The organic ligand is soluble onlyin DCM, and the Fe(II) salt is soluble only in water. Moreover,our previous report determined the stoichiometric complex-ation ratio between the 3TPY ligand and Fe2+ ions is to be 2:3by using UV−vis titration by gradually adding Fe2+ ions to asolution containing 3TPY.29 The chemical structure of Fe-3TPY is represented in Figure 1a by considering the above-mentioned stoichiometric ratio. The comparative UV−Visspectroscopy analysis (Figure 1b) of 3TPY and Fe-3TPYrevealed a notable spectral shift of the peaks. Initially, for3TPY, a distinct absorption peak at 272 nm was observed,attributed to the π−π* transition within its aromatic unit.Upon complexation with Fe2+, this transition underwent asignificant red shift to 312 nm in Fe-3TPY. Additionally, aminor peak appeared at 360 nm, corresponding to the metal(Fe2+) d−d transition, along with an intense peak at 556 nmowing to the MLCT (d of Fe2+ to π* of 3TPY) transition, alsoresponsible for the intense purple color of the CONASH. TheFESEM image consistently revealed a homogeneously smooth,ACS Applied Materials & Interfaces www.acsami.org Research Articlehttps://doi.org/10.1021/acsami.5c13795ACS Appl. Mater. Interfaces 2025, 17, 62499−6250962501https://pubs.acs.org/doi/suppl/10.1021/acsami.5c13795/suppl_file/am5c13795_si_001.pdfhttps://pubs.acs.org/doi/suppl/10.1021/acsami.5c13795/suppl_file/am5c13795_si_001.pdfhttps://pubs.acs.org/doi/suppl/10.1021/acsami.5c13795/suppl_file/am5c13795_si_001.pdfhttps://pubs.acs.org/doi/suppl/10.1021/acsami.5c13795/suppl_file/am5c13795_si_001.pdfhttps://pubs.acs.org/doi/suppl/10.1021/acsami.5c13795/suppl_file/am5c13795_si_001.pdfwww.acsami.org?ref=pdfhttps://doi.org/10.1021/acsami.5c13795?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-asflat nanosheet structure throughout its surface (Figure 1c).The average film thickness of the Fe-3TPY film was maintainedat 350 ± 10 nm through AFM imaging, as shown in Figure 1d,by preparing an interfacial nanosheet over 48 h.29 The bondingenvironment and structural connectivity of Fe-3TPY werecomprehensively examined through XPS analysis. In the core-level scan of N 1s, as shown in Figure 1e, a distinct peakcorresponding to the nitrogen atoms of 3TPY was observed at398.17 eV, which exhibited a slight shift to 399.92 eV in Fe-3TPY.62 Analysis of the Fe 2p core-level scan of Fe-3TPY(Figure 1f) revealed two distinct peaks at Fe 2p3/2 (708.66 eV)and Fe 2p1/2 (721.23 eV). This outcome explicitly confirmedthe coordination of terpyridine moieties with Fe(II) within theFe-3TPY nanosheets. Additionally, the XPS analysis-basedatomic ratios indicated N/Fe ratios of 6.63:1.17, which werevery close to the theoretical N/Fe ratios of the ideal standardbis(terpyridine)−Fe(II) complex of 6:1. The Raman spectra(Figure 1g) of CONASHs exhibited a downward shift in thecharacteristic aromatic C=C or C=N stretching vibrationscompared to the free ligand, confirming the successfulcoordination of Fe(II) to 3TPY. Additionally, the PXRDpattern (Figure 1h) of CONASHs showed an amorphousnature with a broad peak centered at 2θ = ∼21.9,corresponding to a short-range interaction at 4.05 Å. Theextensive optical, structural, and thermal characterizations ofFe-3TPY are provided in our earlier report.29Electrochemical and EC Properties of ECESD. The Fe-3TPY and NiHCF-based sandwich-shaped gel-based quasi-solid-state ECESD was made utilizing a Fe-3TPY-coated ITOas the active working electrode (WE) material and NiHCF-coated ITO as the CE with a LiClO4 and PMMA-basedsemigel electrolyte in between electrodes. Here, the thicknessof the Fe-3TPY layer was 350 ± 10 nm, as mentioned, and theaverage thickness of the NiHCF layer was maintained at 140 ±10 nm (given in the inset of Figure 2a). Before quantitativelyanalyzing the energy storage properties, the energy storagebehavior of the Fe-3TPY-based ECESD was assessed through aCV study by varying scan rates. At the scan rates between 25and 200 mV s−1, the ECESD exhibited a distinct reversibleredox peak identified with the Fe2+/Fe3+ redox couple (Figure2a), indicating the characteristic reversible faradic behavior ofECESD. Notably, increasing scan speeds led to higheroxidative and reductive current densities, indicating theECESD’s low internal resistance and rapid charge-transferkinetics, with the charge storage mechanism described by eq 1:i avb= (1)where a and b are configurable parameters, v is the scan rate,and i is the peak current. We determined b-values of 0.680 foranodic and 0.708 for cathodic current maxima by plottinglog(i) vs log(v) (Figure 2b). This demonstrated thepredominant pseudocapacitive behavior of the Fe-3TPY-based ECESD and facilitated quantitative evaluation ofdiffusive and capacitive contributions to energy storage byusing eq 2:i k v k v1 21/2= + (2)where k1 and k2 are constants derived from the i/v1/2 versus thesquare root of the scan-rate plot.From Figure 2c, we determined k1 as 0.00556 and k2 as0.00223. Consequently, we calculated the pseudocapacitivecontribution of the Fe-3TPY/NiHCF ECESD to be over 80%at a scan rate of 25 mV s−1. The pseudocapacitive contributionFigure 1. (a) Chemical structure of Fe-3TPY. (b) UV−vis spectra.(c) FESEM images of Fe-3TPY. (d) AFM image of the CONASHfilm. Core-level XPS spectra of (e) N 1s for 3TPY (blue) and Fe-3TPY (red) and (f) Fe 2p for Fe-3TPY. (g) Raman spectra ofCONASH film (violet line) and the ligand 3TPY (black) on a glassslide. (h) PXRD pattern of collected CONASH flakes on a Kaptonholder.Figure 2. (a) Scan-rate (ν)-dependent CV study of Fe-3TPY- andNiHCF-based ECESD. (b) Plot for calculating the b value from theanodic (ia) and cathodic (ib) peaks for the ECESD. (c) i/ν1/2 versusthe square root of the scan-rate plot to determine the k1 and k2. (d)Pseudocapacitive and diffusive contributions of Fe-3TPY- andNiHCF-based ECESD at different scan rates.ACS Applied Materials & Interfaces www.acsami.org Research Articlehttps://doi.org/10.1021/acsami.5c13795ACS Appl. Mater. Interfaces 2025, 17, 62499−6250962502https://pubs.acs.org/doi/10.1021/acsami.5c13795?fig=fig1&ref=pdfhttps://pubs.acs.org/doi/10.1021/acsami.5c13795?fig=fig1&ref=pdfhttps://pubs.acs.org/doi/10.1021/acsami.5c13795?fig=fig1&ref=pdfhttps://pubs.acs.org/doi/10.1021/acsami.5c13795?fig=fig1&ref=pdfhttps://pubs.acs.org/doi/10.1021/acsami.5c13795?fig=fig2&ref=pdfhttps://pubs.acs.org/doi/10.1021/acsami.5c13795?fig=fig2&ref=pdfhttps://pubs.acs.org/doi/10.1021/acsami.5c13795?fig=fig2&ref=pdfhttps://pubs.acs.org/doi/10.1021/acsami.5c13795?fig=fig2&ref=pdfwww.acsami.org?ref=pdfhttps://doi.org/10.1021/acsami.5c13795?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-asof EECSD decreased with increasing scan rates, reaching 55%at a 200 mV s−1 scan rate (Figure 2d). These resultsdemonstrate Fe-3TPY’s potential for high-power energystorage applications, making it a viable option for super-capacitor technology.To gain insight into the electrochromism behavior ofasymmetric ECESDs, we monitored the transmittancespectrum change of the ECESD when applying differentvoltages. It is worth noting that the transmittance wasmeasured by subtracting the background of the ITO/glasssubstrate with an electrolyte gel. The transmittance spectra ofECESD revealed the disappearance of the MLCT peak at 556nm (Figure 3a), with a reversible color change from pristinepink to a pale yellowish of the ECESD, as shown in Figure 3b.The CV plot revealed that ECESD exhibited an oxidation peakfor Fe2+ to Fe3+ at +0.64 V and a corresponding reduction peakfor Fe3+ to Fe2+ at +0.37 V, observed at a scan rate of 25 mV/s(Figure 2a). The color change of the ECESD is linked to thereversible Fe2+/Fe3+ redox transition, resulting in the completedisappearance of the 556 nm MLCT peak within a potentialwindow of 0.01 to 1.0 V. The Fe-3TPY-based ECESDexhibited a distinct color change, resulting in a high opticalcontrast (ΔT) of 57.4% at 556 nm. It is worth noting that theincorporation of NiHCF as a CE material did not hamper theoverall transmittance of the device, as the NiHCF electroderevealed a transparent pale yellowish color (Figure S1 inSupporting Information) originating from the d−d transitionin the material.The fundamental EC parameters, such as the switchingspeed, coloration efficiency, and device durability, weredetermined later for the practical applicability of EC materials.The EC parameters of Fe-3TPY were determined using doublepotential chronoamperometric studies, sweeping the potentialbetween +1 and 0.01 V. The switching times, defined as thetime taken for a 95% change in ΔT, were calculated from thetransmittance vs time plot shown in Figure 3c. In general,ECDs with a fast-to-moderate switching time and highcoloration efficiency (η) are desirable for commercialapplications. In this study, the switching times of ECESDwere determined to be 1.28 s for coloration (tc) and 1.69 s forbleaching (tb). “η” is a measure of the device’s energyefficiency, which can be calculated by dividing the quantity ofcharge injected or ejected (Qd) per unit area by the ratio ofoptical density change (ΔOD). The “η” of the CONASH-based hybrid ECESD, calculated from the slope of the ΔOD vsQd plot in Figure 3d, was 619 cm2 C−1, which is higher thanthat of previously reported Fe(II)-containing MSPs.29,47,53,54We also derived the power and energy consumption of theECESD from the chronoamperometric charge−discharge plotgiven in Figure 3e. The power and energy consumed by theCONASH-based hybrid ECESD during electrochromism were2.18 mW/cm2 and 3.6 mJ/cm2, respectively, calculated byFigure 3. (a) Transmittance spectral change of the ECESD with an operating voltage of +1.0 and +0.01 V. (b) Photograph of the color change forthe fabricated ECESD (film size: 1.4 × 1.3 cm2) at different voltages. (c) EC response time determination of the ECESD is based on a 95% changein transmittance. (d) Calculation of coloration efficiency for the Fe-3TPY-based ECESD. (e) Chronoamperometry charge−discharge plot duringthe electrochromism of the ECESD. (f) Power densities of several display technologies: a comparison of the OLED (organic light-emitting diodes,active matrix),63 LCD (liquid crystal display, active matrix, LTPS TFT),64 EPD (electrophoretic displays, active matrix),65 and the fabricatedECESD in the context of power consumption. (g) EC switching performance of Fe-3TPY-NiHCF-based ECESD by applying +1.0 and 0.01 V with5, 4, and 3 s interval time at each voltage, monitoring the transmittance change at 556 nm.ACS Applied Materials & Interfaces www.acsami.org Research Articlehttps://doi.org/10.1021/acsami.5c13795ACS Appl. Mater. Interfaces 2025, 17, 62499−6250962503https://pubs.acs.org/doi/suppl/10.1021/acsami.5c13795/suppl_file/am5c13795_si_001.pdfhttps://pubs.acs.org/doi/10.1021/acsami.5c13795?fig=fig3&ref=pdfhttps://pubs.acs.org/doi/10.1021/acsami.5c13795?fig=fig3&ref=pdfhttps://pubs.acs.org/doi/10.1021/acsami.5c13795?fig=fig3&ref=pdfhttps://pubs.acs.org/doi/10.1021/acsami.5c13795?fig=fig3&ref=pdfwww.acsami.org?ref=pdfhttps://doi.org/10.1021/acsami.5c13795?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-asusing eq 3 as mentioned in the SI at an operating voltage of+1.0 and +0.01 V by taking the 1.4 × 1.3 cm2 film size. We alsocompare the energy consumption data of ECESD with theconventional display technologies in Figure 3f, revealing evenlower energy consumption in our ECESD compared to otherconventional display technologies.63−65 In the cycle stabilitystudy, we evaluated the long-term switching capacity of theECESD within specified holding intervals of 5, 4, and 3 s, asillustrated in Figure 3g. As the ECESD showed faster switchingand very low coloration and bleaching times, we anticipatedswift and reversible switching in any holding times beyond 2 s.Remarkably, the ECESD exhibited exceptional cycle stability,enduring over 50,000 cycles of operation. By accuratelyanalyzing the initial and final optical contrast (ΔT), wedetermined that the ECESD retained approximately 90% of itsinitial ΔT following 50,000 repeated switching events. Thisendurance provides durable performance of the ECESDequivalent to a remarkable 14-year lifespan based on a usagescenario of 10 cycles per day.66,67 This impressive durability isattributed to this device’s extremely low operational voltage(0.01−1 V) and reversible charge-balancing redox reactionsoccurring between the WE and CE. This highlights therobustness and suitability of fabricated ECESD for sustainedpractical applications in various fields.High optical memory within an ECESD is an essential factorin assessing the power efficiency of smart windows. Typically,in an ECESD, the ability of a specific redox state, characterizedby its color or bleaching level, to maintain its originality overan extended period in open-circuit conditions signifies thepotential for creating a power-efficient device.29,47,68 In thiswork, after attaining the fully bleached state at +1 V bias, wecontinually monitored transmittance at 556 nm and the changein optical color to examine the EC memory of the Fe-3TPY-based ECESD. Herein, Figure 4a,b depicts the regeneration oftransmittance and optical color over time under open-circuitconditions, starting from a fully bleached state. The observedgradual increment in transmittance peak and development of apink hue over time resulted from the self-reduction of colorlessFe3+ centers by residual electrons from the electrode underopen-circuit conditions.29 Interestingly, the ECESD demon-strated only a 33.3% recovery of its original color state after 36h (Figure 4c). The electron transport activities between nearbyFe centers via the ligand π cloud and from the electrode toFe3+ centers within the MSP in the bleached state play crucialroles in determining EC memory. In the Fe-3TPY system, thenonconjugated nature of the 3TPY ligand restricted electronhopping through the ligand’s π cloud, showcasing a highlyextending EC memory of Fe-3TPY-NiHCF-based hybridECESD. It is noteworthy that the EC optical memory of ourITO/Fe-3TPY//NiHCF/ITO-based ECESD is not only oneof the best in the MSPs or CONASH category47 but alsoenhanced a lot compared to our earlier report of ITO/Fe-3TPY/ITO-type devices,29 which showed 50% of colorationrecovery only after 25 min in open-circuit conditions.Incorporating NiHCF as the redox-complementary CE in thedevices can reduce the number of residual electrons during theoxidation of Fe-3TPY in the WE to increase the EC opticalmemory in the hybrid device.Moreover, it is essential to understand the electrochemicalreactions occurring between the WE and CE to comprehendthe EC phenomenon of the ECESD. In the diagram given inFigure 4d, in the colored mode, the Fe-3TPY layer isdistinguished by its pink hue, which indicates the presenceof Fe2+ ions. Conversely, the NiHCF layer is represented in alight yellow shade, indicating the presence of Fe3+ ions. Theelectrolyte LiClO4 facilitates electrochemical processes be-tween the two electrodes. We propose a mechanistic insightinto the electrochemical redox reactions occurring within thedevice, defined by eqs 3−7.Electrochemical reaction during bleaching of ECESD:At the WE:nnFe 3TPY . CH COO ClOFe 3TPY CH COO ClO en nn n n23 2 433 2 4[ ] [ ] +[ ] [ ] [ ] +++(3)At CE:n n nnNi Fe (CN) e LiLi Ni Fe (CN)1.52 361.52 26[ ] + +[ ]+ + ++ + +(4)Electrochemical reaction during coloring of ECESD:nnFe 3TPY CH COO ClO eFe 3TPY CH COO ClOn n nn n33 2 423 2 4[ ] [ ] [ ] +[ ] ·[ ] +++(5)nn n nLi Ni Fe (CN)Li Ni Fe (CN) e1.52 261.52 36[ ]+ [ ] ++ + ++ + +(6)Figure 4. (a) Decrease in transmittance of the Fe-3TPY- and NiHCF-based ECESD (film size: 1.8 × 1.1 cm2) from the bleached state tothe colored state at 556 nm under open-circuit conditions. (b)Complete transmittance spectrum of the ECESD at different timeintervals. (c) Photographs of the ECESD under open-circuitconditions at various times after reaching the bleached state. Aschematic representation for the mechanism of electrochromism ofECESD upon applying different voltages is shown: (d) dark mode tobright mode, (e) retention of bright/bleached mode, and (f) brightmode to dark mode.ACS Applied Materials & Interfaces www.acsami.org Research Articlehttps://doi.org/10.1021/acsami.5c13795ACS Appl. Mater. Interfaces 2025, 17, 62499−6250962504https://pubs.acs.org/doi/suppl/10.1021/acsami.5c13795/suppl_file/am5c13795_si_001.pdfhttps://pubs.acs.org/doi/10.1021/acsami.5c13795?fig=fig4&ref=pdfhttps://pubs.acs.org/doi/10.1021/acsami.5c13795?fig=fig4&ref=pdfhttps://pubs.acs.org/doi/10.1021/acsami.5c13795?fig=fig4&ref=pdfhttps://pubs.acs.org/doi/10.1021/acsami.5c13795?fig=fig4&ref=pdfwww.acsami.org?ref=pdfhttps://doi.org/10.1021/acsami.5c13795?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-asAs a result, the predicted redox potential of the ECESD canbe defined asE E Evoltage window Ox,WE Red,CE= (7)When a positive voltage is applied, the oxidation reactiontranspires on the Fe-3TPY film (resulting in the conversion ofFe2+ to Fe3+ at the WE), inducing a color transition frompristine pink to a pale yellowish hue (eq 3). Simultaneously, tomaintain charge neutrality within the system, a reductionreaction takes place on the NiHCF film (involving theconversion of Fe3+ to Fe2+) at the CE (eq 4). In contrast,Li+ and ClO4− ions migrate toward opposite electrodes (Figure4d). Conversely, during the coloration phase, the reversereactions occur at each electrode, with reduction transpiring atthe WE and oxidation at the CE (eqs 5 and 6), as depicted inFigure 4f. In open-circuit conditions, after fully bleaching theECESD, the generated Fe3+ ions undergo self-reduction bytaking the residual electrons from electrodes (Figure 4e). Theinherent nonconjugation ligand can slow down the electronhopping to reduce the self-reduction of Fe-3TPY. Again, theNiHCF component in CE is critical as a charge source/sink,facilitating the swift and facile redox reactions within the Fe-3TPY system. It can also consume the electrons for itsreduction during bleaching, effectively reducing the number ofresidual electrons in WE in open-circuit conditions afterbleaching to increase the optical memory. Additionally, theredox potential of the NiHCF (in Figure S1c in SupportingInformation) regulated the overall potential of Fe-3TPY-NiHCF-based hybrid ECESD to obtain an overall potentialwindow of +0.01 to +1.0 V.Capacitive Property of ECESD. The energy storageproperty of ITO/Fe-3TPY/LiClO4/NiHCF/ITO-basedECESD was examined by galvanostatic charge−discharge(GCD) and electrochemical impedance spectroscopy (EIS)techniques. As discussed earlier, the nonlinear CV curves of theECESD showed excellent reversible redox behavior, whichindicated that the Fe-3TPY-based ECESD disclosed aneffective charge-storage pseudocapacitive system. The capacityto store charge in Fe-3TPY-based ECESD was examined by aGCD study at different current densities ranging from 1 to 15A/cm3 in the +0.01 to +1.0 V potential window (Figure 5a).The nonlinear charge−discharge curves in the GCD studyagain confirmed the predominant pseudocapacitive charge-storage mechanism for the electrodes, which prevailed bysurface faradic reaction at both electrodes. The ECESDshowed a negligible iR drop of only 0.15 V in the GCDbehavior. The minimal iR drop (Figure S2a in SupportingInformation) originated from internal resistance caused by theelectrolyte and electrode−electrolyte contact. Additionally,including a NiHCF layer as a charge-storage layer wouldprobably increase facile ion diffusion, resulting in a minimal iRdrop for this ECESD. The volumetric capacitance wascalculated as 248.1 F/cm3 at 1 A/cm3 and slightly decreasedto 211.5 F/cm3 at 15 A/cm3 (Figure 5b), indicating theECESD’s rapid and high-rate charge-storage ability. Tounderstand the charge-transport properties of the ECESD,we performed an EIS study in the 5 Hz to 1 kHz frequencyrange. The Nyquist plot (Figure 5c) revealed an interfacialcharge-transfer resistance (RCT) of 180.2 Ω, and the slope inthe lower frequency region showcased the ECESD’s diffusivebehavior. After 40,000 consecutive charge−discharge cycles ata current density of 15 A/cm3, the constructed ECESDdemonstrated ∼80% retention of the initial remarkable long-term charge−discharge stability, retaining approximately 80%of its initial volumetric capacitance (Figure 5d). Additionally,Figure S2b in Supporting Information illustrates this trend’sfirst and last GCD cycles. Furthermore, the Coulombicefficiency of the ECESD remained at 97% after completing40,000 cycles, revealing its remarkable performance forcommercial applications. At a current density of 1 A/cm3,the ECESD exhibited a power density of 0.5 W/cm3 and anenergy density of 34.45 mW h/cm3. These values improved to7.5 W/cm3 for power density and 29.37 mW h/cm3 for energydensity at a higher current density of 15 A/cm3, as shown inFigure 5e. The intentional selection of a redox-active CEwithin the ECESD promoted redox activities between theanode and cathode, enabling a reversible push−pull effect thatenhances the energy storage performance of Fe-3TPY- andFigure 5. (a) GCD profiles of Fe-3TPY- and NiHCF-based ECESD at various current densities ranging from 1 to 15 A/cm3. (b) Volumetriccapacitance change plotted against Coulombic efficiency at different current densities. (c) Nyquist plot of the ECESD. (d) Retention plot showingvolumetric capacitance and Coulombic efficiency after 40,000 GCD cycles at 15 A/cm3. (e) Power and energy densities of the ECESD at variouscurrent densities. (f) Ragone plot of the ECESD.ACS Applied Materials & Interfaces www.acsami.org Research Articlehttps://doi.org/10.1021/acsami.5c13795ACS Appl. Mater. Interfaces 2025, 17, 62499−6250962505https://pubs.acs.org/doi/suppl/10.1021/acsami.5c13795/suppl_file/am5c13795_si_001.pdfhttps://pubs.acs.org/doi/suppl/10.1021/acsami.5c13795/suppl_file/am5c13795_si_001.pdfhttps://pubs.acs.org/doi/suppl/10.1021/acsami.5c13795/suppl_file/am5c13795_si_001.pdfhttps://pubs.acs.org/doi/10.1021/acsami.5c13795?fig=fig5&ref=pdfhttps://pubs.acs.org/doi/10.1021/acsami.5c13795?fig=fig5&ref=pdfhttps://pubs.acs.org/doi/10.1021/acsami.5c13795?fig=fig5&ref=pdfhttps://pubs.acs.org/doi/10.1021/acsami.5c13795?fig=fig5&ref=pdfwww.acsami.org?ref=pdfhttps://doi.org/10.1021/acsami.5c13795?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-asNIHCF-based ECESDs. The volumetric energy and powerdensities of the hybrid ECESD were compared to those ofpreviously published high-performance ECESD in a Ragoneplot, as shown in Figure 5f. Uncracked smooth surface of theFe-3TPY film after prolonged ECESD operation, confirmed bySEM, indicates the high durability of the nanosheets (FigureS3, Supporting Information). The above data demonstrate theefficient energy storage performance of the ECESD, high-lighting the active participation of both electrode materials inthe redox mechanism. This synergistic interaction enhancesthe overall performance, as each material contributes to thecharge-storage and transfer processes. The Fe-3TPY andNiHCF electrodes work in tandem to provide high capacityand stability, ultimately producing robust and effective energy.We also fabricated a device using a larger film (3 × 2.4 cm2) bythe interfacial polymerization method (Figure S4, SupportingInformation). The ECESD using the larger film exhibitedsimilar EC behavior at an applied voltage of +1.5/+0.01 V. Thecalculated energy consumption and power consumption of thedevice were 3.8 mJ/cm2 and 2.2 mW/cm2, respectively, whichare consistent with the smaller ECESD described above.However, fabricating much larger films remains challengingdue to the need for precise control of the interface. Furtherresearch is needed to design vibration-free platforms, developoptimized vessels, and achieve controlled solvent removal toenable mass production of large, crack-free films.Integrating high-performance energy storage and ECbehavior is very important for the device to be used as anindicative supercapacitor for next-generation electronic devi-ces. While measuring the energy storage performance, theECESD changes its observable color depending on the device’scharge state, potential, and redox state. We monitored the insitu transmittance change of the hybrid ECESD at 556 nmduring the charging and discharging process through GCD at acurrent density of 1 A/cm3 (Figure 6a). The figure providedthe correlation between the transmittance and stored energystate of the ECESD, which allows users to predict the amountof charge storage by observing the color variation of theECESD. The Fe-3TPY-based ECESD changes from pristinepink in its fully discharged state to a pale yellowish color whenfully charged, as shown in Figure 6a inset. This demonstratesthe correlation between charge-storage level and observabletransmittance change. Furthermore, we have measured thetransmittance changes of the devices during the charging−discharging in different current densities starting from 1 to 15A/cm3. As shown in Figure 6b, the results revealed that ourECESD could track the color change over this wide range ofcurrent densities.The EC energy storage performance of the nonconjugatedFe-3TPY-based ECESD was compared with a conjugatedligand-based MSP Poly-Fe, maintaining a similar devicearchitecture. A chemical structure and the synthesis protocolof Poly-Fe are mentioned in Figure S5a. In our previousarticle,67 we have shown the detailed durable EC performanceof a poly-Fe-based EC device with NiHCF as a countermaterial. As shown in Figure S5b, the device showed areversible purple to bleached EC transition in the operatingvoltage window of +1.2/+0.01 V with an optical contrast of55% at 580 nm (Figure S5c in Supporting Information). ThePoly-Fe- and NiHCF-based fabricated asymmetric devicerevealed comparatively much lower optical memory, as it canregain ∼17.8% of the initial optical contrast after 75 min,where Fe-3TPY-/NiHCF-based ECD could gain only ∼10% ofcolor after 75 min, as shown in Figure 4a. The comparativelylow optical memory in the Poly-Fe system is basically due tothe conjugated configuration at the ligand that helped in fasterelectron transfer or electron hopping inside the system underopen-circuit conditions to the self-reduction of the Fe(III)center. The GCD study of the Poly-Fe-/NiHCF-based devicerevealed similar nonlinear behavior with a comparatively highiR drop of 0.5 V (Figure S5d in Supporting Information), dueto a certain self-reduction tendency of the device in thepresence of a fully conjugated system. The volumetriccapacitance of the device was further calculated as 32 F/cm3at 0.05 A/cm3, further decreasing to 23.5 F/cm3 at 1 A/cm3(Figure S5e in Supporting Information). These observationssuggested that the intentional incorporation of a non-conjugated system provided high optical memory and highvolumetric capacitance with a slightly higher voltage window.Moreover, we compared the EC energy storage performanceof the Fe-3TPY-based device in the absence of NiHCF byfabricating the device as ITO/Fe-3TPY/LiClO4/ITO. Due tothe absence of NiHCF, the operating voltage window of thedevice increased to +2.5 to −2 V, as shown in Figure S6a inSupporting Information. The GCD study of the device inFigure S6b revealed nonlinear behavior with a very high iRdrop of approximately 2.5 V. This large iR drop resulted indecreased performance, with the volumetric capacitancecalculated at only 32 F/cm3 at 0.05 A/cm3, further decreasingto 23.5 F/cm3 at 1 A/cm3 (Figure S6c in SupportingInformation). The GCD cyclic performance in Figure S6dshowed a significant capacitance loss within just 1000 cycles.The EC study also revealed that the optical contrast of thedevice slightly decreased to 53% (Figure S6e in SupportingInformation). The optical memory of the device was drasticallyFigure 6. (a) Collective transmission change and GCD prolife at 1 A/cm3 current density with the corresponding color change of theECESD at different voltage states in the inset. (b) Transmittancechanges of the device when different current densities are applied,from 1 to 15 A/cm3. (c) Demonstration of three ECESDs in a seriesfor light illumination of a 10-blue LED panel. (d−g) Gradual colorgeneration of the ECESD from the fully charged bleached state, withthe diminishing brightness of the LED panel over time.ACS Applied Materials & Interfaces www.acsami.org Research Articlehttps://doi.org/10.1021/acsami.5c13795ACS Appl. Mater. Interfaces 2025, 17, 62499−6250962506https://pubs.acs.org/doi/suppl/10.1021/acsami.5c13795/suppl_file/am5c13795_si_001.pdfhttps://pubs.acs.org/doi/suppl/10.1021/acsami.5c13795/suppl_file/am5c13795_si_001.pdfhttps://pubs.acs.org/doi/suppl/10.1021/acsami.5c13795/suppl_file/am5c13795_si_001.pdfhttps://pubs.acs.org/doi/suppl/10.1021/acsami.5c13795/suppl_file/am5c13795_si_001.pdfhttps://pubs.acs.org/doi/suppl/10.1021/acsami.5c13795/suppl_file/am5c13795_si_001.pdfhttps://pubs.acs.org/doi/suppl/10.1021/acsami.5c13795/suppl_file/am5c13795_si_001.pdfhttps://pubs.acs.org/doi/suppl/10.1021/acsami.5c13795/suppl_file/am5c13795_si_001.pdfhttps://pubs.acs.org/doi/suppl/10.1021/acsami.5c13795/suppl_file/am5c13795_si_001.pdfhttps://pubs.acs.org/doi/suppl/10.1021/acsami.5c13795/suppl_file/am5c13795_si_001.pdfhttps://pubs.acs.org/doi/suppl/10.1021/acsami.5c13795/suppl_file/am5c13795_si_001.pdfhttps://pubs.acs.org/doi/suppl/10.1021/acsami.5c13795/suppl_file/am5c13795_si_001.pdfhttps://pubs.acs.org/doi/suppl/10.1021/acsami.5c13795/suppl_file/am5c13795_si_001.pdfhttps://pubs.acs.org/doi/suppl/10.1021/acsami.5c13795/suppl_file/am5c13795_si_001.pdfhttps://pubs.acs.org/doi/10.1021/acsami.5c13795?fig=fig6&ref=pdfhttps://pubs.acs.org/doi/10.1021/acsami.5c13795?fig=fig6&ref=pdfhttps://pubs.acs.org/doi/10.1021/acsami.5c13795?fig=fig6&ref=pdfhttps://pubs.acs.org/doi/10.1021/acsami.5c13795?fig=fig6&ref=pdfwww.acsami.org?ref=pdfhttps://doi.org/10.1021/acsami.5c13795?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-asaffected, as it regained its complete optical contrast within 60min in open-circuit conditions (Figure S6f), indicating a fastcharge loss of the energy storage device. These observationssuggest that incorporating suitable CE materials can enhancethe dual-ion-based redox mechanism. Each electrode’s push−pull effect improves energy storage and EC performance.Moreover, we have compared the key performanceparameters of the Fe-3TPY system with those of the previouslyreported MSP-based EC supercapacitor materials in Table S1of SI. The comparison revealed a higher coloration efficiencyand capacitance for the Fe-3TPY system with a comparableenergy and power density to previous reported materials.Finally, we have demonstrated a proof-of-concept LED bulbillumination experiment using our lab-built ITO/Fe-3TPY-/LiClO4/ITO-based ECESD (Figure 6c), with a diameter ofapproximately 1.5 × 1.5 cm2. The prepared three ECESD inseries connection effectively illuminated 10-blue LED bulbs(∼2.8 V each) panel connected by parallel connection, asshown in Figure 6d, once the devices were fully charged. Theemission brightness of the LED panel gradually reduced as thedevices regained their color from pale yellowish (charge state)to pristine pink (discharge state) over time, as shown in Figure6d−g. Therefore, the EC color-indexed hybrid energy storagedevice has the potential to be used as a visually monitoredenergy storage management system. As the reference, the air-referenced transmittance of the devices is also provided inFigure S7, Supporting Information.■ CONCLUSIONSIn summary, the as-synthesized nonconjugated Fe-3TPYCONASH was applied in a hybrid ECESD by assemblingNiHCF as CE and Li+ gel electrolyte. The electrochemicalanalysis revealed the predominant pseudocapacitive behavior(∼55% at 200 mV s−1 scan rate) of the ECESD during theredox transition. The fabricated ECESD displayed remarkableEC properties from pristine purple to pale yellowish,sustainable optical contrast (57.4% at 556 nm), rapidcoloration and bleaching times (1.28 and 1.69 s), and a veryhigh coloration efficiency of 619 cm2 C−1 with very less energyconsumption (3.6 mJ/cm2) compared to the commercialdisplay devices. Importantly, the ECESD revealed an excellent50,000 EC cyclic durability and a very high optical memory(only ∼33% color retention after 36 h), indicating therobustness and energy efficiency of the EC device. Addition-ally, the ECESD also disclosed a high volumetric capacitanceof 248.1 F/cm3 at 1 A/cm3 along with a high energy and powerdensity of 29.37 mW h/cm3 and 7.5 W/cm3, respectively. TheECESD also demonstrates 40,000 continuous GCD perform-ance and represents an attractive example for color-indicativeenergy storage devices for practical applicability. This studyoffers the energy efficiency of ECESDs in different aspects andthe device’s robust performance for a prolonged period, withprospective applications in next-generation energy storage,enriching EC energy storage technology.■ ASSOCIATED CONTENT*sı Supporting InformationThe Supporting Information is available free of charge athttps://pubs.acs.org/doi/10.1021/acsami.5c13795.Details of the synthesis and characterizations of theCONASH; fabrication of the hybrid ECESD; calcu-lations; thickness measurements; CV; UV; and GCDstudies (PDF)■ AUTHOR INFORMATIONCorresponding AuthorsChanchal Chakraborty − Department of Chemistry, BirlaInstitute of Technology & Science (BITS) Pilani, HyderabadCampus, Hyderabad, Telangana 500078, India; MaterialsCenter for Sustainable Energy & Environment (McSEE),Birla Institute of Technology and Science, HyderabadCampus, Hyderabad 500078, India; orcid.org/0000-0002-4829-1367; Email: chanchal@hyderabad.bits-pilani.ac.inMasayoshi Higuchi − Electronic Functional MacromoleculesGroup, National Institute for Materials Science (NIMS),Tsukuba 305-0044, Japan; orcid.org/0000-0001-9877-1134; Email: higuchi.masayoshi@nims.go.jpAuthorsSusmita Roy − Department of Chemistry, Birla Institute ofTechnology & Science (BITS) Pilani, Hyderabad Campus,Hyderabad, Telangana 500078, India; Electronic FunctionalMacromolecules Group, National Institute for MaterialsScience (NIMS), Tsukuba 305-0044, JapanSayan Halder − Department of Chemistry, Birla Institute ofTechnology & Science (BITS) Pilani, Hyderabad Campus,Hyderabad, Telangana 500078, IndiaSarda Sharma − Department of Electronics andCommunication Engineering, Amrita School of Engineering,Bengaluru, Amrita Vishwa Vidyapeetham, Bengaluru560035, IndiaKarumbaiah N. Chappanda − Sensors and Nano Electronics(SANE) Lab, School of Applied Engineering and Technology,Southern Illinois University Carbondale, Carbondale, Illinois62901, United StatesComplete contact information is available at:https://pubs.acs.org/10.1021/acsami.5c13795Author ContributionsThe manuscript was written with contributions from allauthors. All authors have approved the final version of themanuscript.NotesThe authors declare no competing financial interest.■ ACKNOWLEDGMENTSC.C. thanks to the SERB-CRG (CRG/2023/002310) projectfrom the Science & Engineering Research Board (SERB),India, for the financial support. This research was alsosupported by the Mirai project (JPMJMI21I4) from theJapan Science and Technology Agency (JST) and theEnvironment Research and Technology Development Fund(JPMEERF20221M02) from Environmental Restoration andConservation Agency (ERCA). We thank both BITS PilaniHyderabad Campus, India, and National Institute for MaterialsScience (NIMS), 1-1 Namiki, Japan, for the instrumentalfacilities.■ REFERENCES(1) Krishnamoorthy, K.; Pazhamalai, P.; Mariappan, V. K.;Nardekar, S. S.; Sahoo, S.; Kim, S.-J. Probing the Energy ConversionProcess in Piezoelectric-Driven Electrochemical Self-Charging Super-ACS Applied Materials & Interfaces www.acsami.org Research Articlehttps://doi.org/10.1021/acsami.5c13795ACS Appl. Mater. Interfaces 2025, 17, 62499−6250962507https://pubs.acs.org/doi/suppl/10.1021/acsami.5c13795/suppl_file/am5c13795_si_001.pdfhttps://pubs.acs.org/doi/suppl/10.1021/acsami.5c13795/suppl_file/am5c13795_si_001.pdfhttps://pubs.acs.org/doi/suppl/10.1021/acsami.5c13795/suppl_file/am5c13795_si_001.pdfhttps://pubs.acs.org/doi/10.1021/acsami.5c13795?goto=supporting-infohttps://pubs.acs.org/doi/suppl/10.1021/acsami.5c13795/suppl_file/am5c13795_si_001.pdfhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Chanchal+Chakraborty"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://orcid.org/0000-0002-4829-1367https://orcid.org/0000-0002-4829-1367mailto:chanchal@hyderabad.bits-pilani.ac.inmailto:chanchal@hyderabad.bits-pilani.ac.inhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Masayoshi+Higuchi"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://orcid.org/0000-0001-9877-1134https://orcid.org/0000-0001-9877-1134mailto:higuchi.masayoshi@nims.go.jphttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Susmita+Roy"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Sayan+Halder"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Sarda+Sharma"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://pubs.acs.org/action/doSearch?field1=Contrib&text1="Karumbaiah+N.+Chappanda"&field2=AllField&text2=&publication=&accessType=allContent&Earliest=&ref=pdfhttps://pubs.acs.org/doi/10.1021/acsami.5c13795?ref=pdfhttps://doi.org/10.1038/s41467-020-15808-6https://doi.org/10.1038/s41467-020-15808-6www.acsami.org?ref=pdfhttps://doi.org/10.1021/acsami.5c13795?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ascapacitor Power Cell Using Piezoelectrochemical Spectroscopy. Nat.Commun. 2020, 11 (1), 2351.(2) Kammen, D. M.; Sunter, D. A. City-Integrated RenewableEnergy for Urban Sustainability. Science 2016, 352 (6288), 922−928.(3) Hassan, M.; Li, P.; Lin, J.; Li, Z.; Javed, M. S.; Peng, Z.; Celebi,K. Smart Energy Storage: W18O49 NW/Ti3C2Tx Composite-Enabled All Solid State Flexible Electrochromic Supercapacitors.Small 2024, 20, No. 2400278.(4) Gu, C.; Jia, A.-B.; Zhang, Y.-M.; Zhang, S. X.-A. EmergingElectrochromic Materials and Devices for Future Displays. Chem. Rev.2022, 122 (18), 14679−14721.(5) Ma, Q.; Chen, J.; Zhang, H.; Su, Y.; Jiang, Y.; Dong, S. Dual-Function Self-Powered Electrochromic Batteries with Energy Storageand Display Enabled by Potential Difference. ACS Energy Lett. 2023, 8(1), 306−313.(6) Tong, Z.; Zhu, X.; Xu, H.; Li, Z.; Li, S.; Xi, F.; Kang, T.; Ma, W.;Lee, C. Multivalent-Ion Electrochromic Energy Saving and StorageDevices. Adv. Funct Materials 2025, 35, No. 2308989.(7) Wang, M.; Li, X.; Liu, L.; Li, B.; Xun, J.; Wang, L.; Wang, H.;Hu, S.; Li, C. Carbon Dots as Multifunctional Electrolyte Additivestoward Multicolor and Low Self-Discharge Electrochromic EnergyStorage Devices. Energy Storage Materials 2024, 65, No. 103110.(8) Tang, Y.; Qiao, H.; Chen, X.; Huang, Z.; Qi, X. PerformanceOptimization for Multicolor Electrochromic Devices: Morphologyand Composition Regulation of Inorganic Electrochromic Materialsand Selectivity of Ions. Adv. Materials Technologies 2024, 9,No. 2302139.(9) Li, L.; Yu, Z.; Ye, C.; Song, Y. Structural Color BoostedElectrochromic Devices: Strategies and Applications. Adv. FunctMaterials 2024, 34 (12), No. 2311845.(10) Zhou, K.; Wang, H.; Jiu, J.; Liu, J.; Yan, H.; Suganuma, K.Polyaniline Films with Modified Nanostructure for BifunctionalFlexible Multicolor Electrochromic and Supercapacitor Applications.Chemical Engineering Journal 2018, 345, 290−299.(11) Jiao, X.; Li, G.; Yuan, Z.; Zhang, C. High-Performance FlexibleElectrochromic Supercapacitor with a Capability of QuantitativeVisualization of Its Energy Storage Status through ElectrochromicContrast. ACS Appl. Energy Mater. 2021, 4 (12), 14155−14168.(12) Zhou, S.; Wang, S.; Zhou, S.; Xu, H.; Zhao, J.; Wang, J.; Li, Y.An Electrochromic Supercapacitor Based on an MOF DerivedHierarchical-Porous NiO Film. Nanoscale 2020, 12 (16), 8934−8941.(13) Guo, Q.; Zhao, X.; Li, Z.; Wang, D.; Nie, G. A Novel Solid-State Electrochromic Supercapacitor with High Energy StorageCapacity and Cycle Stability Based on Poly(5-Formylindole)/WO3Honeycombed Porous Nanocomposites. Chemical Engineering Journal2020, 384, No. 123370.(14) Guo, Q.; Li, J.; Zhang, B.; Nie, G.; Wang, D. High-PerformanceAsymmetric Electrochromic-Supercapacitor Device Based on Poly-(Indole-6-Carboxylicacid)/TiO 2 Nanocomposites. ACS Appl. Mater.Interfaces 2019, 11 (6), 6491−6501.(15) Dewan, A.; Narayanan, R.; Thotiyl, M. O. A Multi-ChromicSupercapacitor of High Coloration Efficiency Integrating a MOF-Derived V 2 O 5 Electrode. Nanoscale 2022, 14 (46), 17372−17384.(16) Hou, Z.; Zhang, X.; Li, X.; Zhu, Y.; Liang, J.; Qian, Y.Surfactant Widens the Electrochemical Window of an AqueousElectrolyte for Better Rechargeable Aqueous Sodium/Zinc Battery. J.Mater. Chem. A 2017, 5 (2), 730−738.(17) Xu, K. Nonaqueous Liquid Electrolytes for Lithium-BasedRechargeable Batteries. Chem. Rev. 2004, 104 (10), 4303−4418.(18) Hao, Q.; Li, Z.-J.; Lu, C.; Sun, B.; Zhong, Y.-W.; Wan, L.-J.;Wang, D. Oriented Two-Dimensional Covalent Organic FrameworkFilms for Near-Infrared Electrochromic Application. J. Am. Chem. Soc.2019, 141 (50), 19831−19838.(19) Cai, G.; Cui, P.; Shi, W.; Morris, S.; Lou, S. N.; Chen, J.; Ciou,J.; Paidi, V. K.; Lee, K.; Li, S.; Lee, P. S. One-Dimensional π − dConjugated Coordination Polymer for Electrochromic Energy StorageDevice with Exceptionally High Performance. Advanced Science 2020,7 (20), No. 1903109.(20) Kortz, C.; Hein, A.; Ciobanu, M.; Walder, L.; Oesterschulze, E.Complementary Hybrid Electrodes for High Contrast ElectrochromicDevices with Fast Response. Nat. Commun. 2019, 10 (1), 4874.(21) Bai, Z.; Li, R.; Ping, L.; Fan, Q.; Lu, Z.; Hou, C.; Zhang, Q.; Li,Y.; Li, K.; Ling, X.; Wang, H. Photo-Induced Self-Reduction EnablingUltralow Threshold Voltage Energy-Conservation Electrochromism.Chemical Engineering Journal 2023, 452, No. 139645.(22) Chen, X.; Shen, X.; Li, B.; Peng, H.; Cheng, X.; Li, B.; Zhang,X.; Huang, J.; Zhang, Q. Ion-Solvent Complexes Promote GasEvolution from Electrolytes on a Sodium Metal Anode. Angew. Chem.Int. Ed 2018, 57 (3), 734−737.(23) Qiu, W.; Feng, Y.; Luo, N.; Chen, S.; Wang, D. Sandwich-likeSound-Driven Triboelectric Nanogenerator for Energy Harvestingand Electrochromic Based on Cu Foam. Nano Energy 2020, 70,No. 104543.(24) Macher, S.; Schott, M.; Dontigny, M.; Guerfi, A.; Zaghib, K.;Posset, U.; Löbmann, P. Large-Area Electrochromic Devices onFlexible Polymer Substrates with High Optical Contrast andEnhanced Cycling Stability. Adv. Materials Technologies 2021, 6 (2),No. 2000836.(25) Pande, G. K.; Choi, J. H.; Lee, J.-E.; Kim, Y. E.; Choi, J. H.;Choi, H. W.; Chae, H. G.; Park, J. S. Octa-Viologen SubstitutedPolyhedral Oligomeric Silsesquioxane Exhibiting Outstanding Electro-chromic Performances. Chemical Engineering Journal 2020, 393,No. 124690.(26) Ghosh, T.; Kandpal, S.; Rani, C.; Chaudhary, A.; Kumar, R.Recipe for Fabricating Optimized Solid-State Electrochromic Devicesand Its Know-How: Challenges and Future. Adv. Opt. Mater. 2023, 11(12), No. 2203126.(27) Kandpal, S.; Bansal, L.; Game, O. S.; Kumar, R. Self-SufficientElectrochromic Solar Cells: Photovoltaic and Color ModulatingSmart Windows. ACS Appl. Mater. Interfaces 2025, 17 (2), 2703−2715.(28) Halder, S.; Garg, S.; Chakraborty, C. Introducing Non-Conjugated Ionic Spacer in Metallo-Supramolecular Polymer:Generation of Nanofibers for High-Performance ElectrochromicSupercapacitor. Chem. Eng. J. 2023, 470, No. 144361.(29) Roy, S.; Chakraborty, C. Interfacial Coordination NanosheetBased on Nonconjugated Three-Arm Terpyridine: A Highly Color-Efficient Electrochromic Material to Converge Fast Switching withLong Optical Memory. ACS Appl. Mater. Interfaces 2020, 12 (31),35181−35192.(30) Roy, S.; Chakraborty, C. Nanostructured Metallo-Supra-molecular Polymer-Based Gel-Type Electrochromic Devices withUltrafast Switching Time and High Colouration Efficiency. J. Mater.Chem. C 2019, 7 (10), 2871−2879.(31) Roy, S.; Chakraborty, C. Sub-Second Electrochromic Switchingand Ultra-High Coloration Efficiency in Halloysite NanoclayIncorporated Metallo-Supramolecular Polymer Nano-Hybrid BasedElectrochromic Device. Sol. Energy Mater. Sol. Cells 2020, 208,No. 110392.(32) Halder, S.; Chakraborty, C. Fe(II)-Based Dual FunctionMetallo-Supramolecular Polymer with Thiazolothiazole Spacer forHigh-Performance Electrochromic Supercapattery. Sol. Energy Mater.Sol. Cells 2023, 254, No. 112288.(33) Winter, A.; Schubert, U. S. Synthesis and Characterization ofMetallo-Supramolecular Polymers. Chem. Soc. Rev. 2016, 45 (19),5311−5357.(34) Janoschka, T.; Hager, M. D.; Schubert, U. S. Powering up theFuture: Radical Polymers for Battery Applications. Adv. Mater. 2012,24 (48), 6397−6409.(35) Bentz, K. C.; Cohen, S. M. Supramolecular Metallopolymers:From Linear Materials to Infinite Networks. Angew. Chem. Int. Ed2018, 57 (46), 14992−15001.(36) Halder, S.; Chakraborty, C. Fe(II)−Pt(II) Based Metallo-Supramolecular Macrocycle Nanoarchitectonics for High-Perform-ance Gel-State Electrochromic Device. Dyes Pigm. 2023, 212,No. 111131.ACS Applied Materials & Interfaces www.acsami.org Research Articlehttps://doi.org/10.1021/acsami.5c13795ACS Appl. Mater. Interfaces 2025, 17, 62499−6250962508https://doi.org/10.1038/s41467-020-15808-6https://doi.org/10.1126/science.aad9302https://doi.org/10.1126/science.aad9302https://doi.org/10.1002/smll.202400278https://doi.org/10.1002/smll.202400278https://doi.org/10.1021/acs.chemrev.1c01055?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acs.chemrev.1c01055?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acsenergylett.2c02346?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acsenergylett.2c02346?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acsenergylett.2c02346?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1002/adfm.202308989https://doi.org/10.1002/adfm.202308989https://doi.org/10.1016/j.ensm.2023.103110https://doi.org/10.1016/j.ensm.2023.103110https://doi.org/10.1016/j.ensm.2023.103110https://doi.org/10.1002/admt.202302139https://doi.org/10.1002/admt.202302139https://doi.org/10.1002/admt.202302139https://doi.org/10.1002/admt.202302139https://doi.org/10.1002/adfm.202311845https://doi.org/10.1002/adfm.202311845https://doi.org/10.1016/j.cej.2018.03.175https://doi.org/10.1016/j.cej.2018.03.175https://doi.org/10.1021/acsaem.1c02927?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acsaem.1c02927?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acsaem.1c02927?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acsaem.1c02927?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1039/D0NR01152Ehttps://doi.org/10.1039/D0NR01152Ehttps://doi.org/10.1016/j.cej.2019.123370https://doi.org/10.1016/j.cej.2019.123370https://doi.org/10.1016/j.cej.2019.123370https://doi.org/10.1016/j.cej.2019.123370https://doi.org/10.1021/acsami.8b19505?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acsami.8b19505?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acsami.8b19505?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1039/D2NR04841Hhttps://doi.org/10.1039/D2NR04841Hhttps://doi.org/10.1039/D2NR04841Hhttps://doi.org/10.1039/C6TA08736Ahttps://doi.org/10.1039/C6TA08736Ahttps://doi.org/10.1021/cr030203g?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/cr030203g?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/jacs.9b09956?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/jacs.9b09956?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1002/advs.201903109https://doi.org/10.1002/advs.201903109https://doi.org/10.1002/advs.201903109https://doi.org/10.1038/s41467-019-12617-4https://doi.org/10.1038/s41467-019-12617-4https://doi.org/10.1016/j.cej.2022.139645https://doi.org/10.1016/j.cej.2022.139645https://doi.org/10.1002/anie.201711552https://doi.org/10.1002/anie.201711552https://doi.org/10.1016/j.nanoen.2020.104543https://doi.org/10.1016/j.nanoen.2020.104543https://doi.org/10.1016/j.nanoen.2020.104543https://doi.org/10.1002/admt.202000836https://doi.org/10.1002/admt.202000836https://doi.org/10.1002/admt.202000836https://doi.org/10.1016/j.cej.2020.124690https://doi.org/10.1016/j.cej.2020.124690https://doi.org/10.1016/j.cej.2020.124690https://doi.org/10.1002/adom.202203126https://doi.org/10.1002/adom.202203126https://doi.org/10.1021/acsami.4c17552?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acsami.4c17552?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acsami.4c17552?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1016/j.cej.2023.144361https://doi.org/10.1016/j.cej.2023.144361https://doi.org/10.1016/j.cej.2023.144361https://doi.org/10.1016/j.cej.2023.144361https://doi.org/10.1021/acsami.0c06045?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acsami.0c06045?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acsami.0c06045?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acsami.0c06045?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1039/C8TC06138Fhttps://doi.org/10.1039/C8TC06138Fhttps://doi.org/10.1039/C8TC06138Fhttps://doi.org/10.1016/j.solmat.2019.110392https://doi.org/10.1016/j.solmat.2019.110392https://doi.org/10.1016/j.solmat.2019.110392https://doi.org/10.1016/j.solmat.2019.110392https://doi.org/10.1016/j.solmat.2023.112288https://doi.org/10.1016/j.solmat.2023.112288https://doi.org/10.1016/j.solmat.2023.112288https://doi.org/10.1039/C6CS00182Chttps://doi.org/10.1039/C6CS00182Chttps://doi.org/10.1002/adma.201203119https://doi.org/10.1002/adma.201203119https://doi.org/10.1002/anie.201806912https://doi.org/10.1002/anie.201806912https://doi.org/10.1016/j.dyepig.2023.111131https://doi.org/10.1016/j.dyepig.2023.111131https://doi.org/10.1016/j.dyepig.2023.111131www.acsami.org?ref=pdfhttps://doi.org/10.1021/acsami.5c13795?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as(37) Razavi, S. A. A.; Chen, W.; Zhou, H.-C.; Morsali, A. Tuningredox activity in metal−organic frameworks: From structure toapplication. Coord. Chem. Rev. 2024, 517, No. 216004.(38) Bauer, T.; Zheng, Z.; Renn, A.; Enning, R.; Stemmer, A.;Sakamoto, J.; Schlüter, A. D. Synthesis of Free-Standing, MonolayeredOrganometallic Sheets at the Air/Water Interface. Angew. Chem. Int.Ed. 2011, 50 (34), 7879−7884.(39) Takada, K.; Sakamoto, R.; Yi, S.-T.; Katagiri, S.; Kambe, T.;Nishihara, H. Electrochromic Bis(Terpyridine)Metal Complex Nano-sheets. J. Am. Chem. Soc. 2015, 137 (14), 4681−4689.(40) Hmadeh, M.; Lu, Z.; Liu, Z.; Gándara, F.; Furukawa, H.; Wan,S.; Augustyn, V.; Chang, R.; Liao, L.; Zhou, F.; Perre, E.; Ozolins, V.;Suenaga, K.; Duan, X.; Dunn, B.; Yamamto, Y.; Terasaki, O.; Yaghi,O. M. New Porous Crystals of Extended Metal-Catecholates. Chem.Mater. 2012, 24 (18), 3511−3513.(41) Sun, X.; Wu, K.-H.; Sakamoto, R.; Kusamoto, T.; Maeda, H.;Ni, X.; Jiang, W.; Liu, F.; Sasaki, S.; Masunaga, H.; Nishihara, H.Bis(Aminothiolato)Nickel Nanosheet as a Redox Switch forConductivity and an Electrocatalyst for the Hydrogen EvolutionReaction. Chem. Sci. 2017, 8 (12), 8078−8085.(42) Tsukamoto, T.; Takada, K.; Sakamoto, R.; Matsuoka, R.;Toyoda, R.; Maeda, H.; Yagi, T.; Nishikawa, M.; Shinjo, N.; Amano,S.; Iokawa, T.; Ishibashi, N.; Oi, T.; Kanayama, K.; Kinugawa, R.;Koda, Y.; Komura, T.; Nakajima, S.; Fukuyama, R.; Fuse, N.; Mizui,M.; Miyasaki, M.; Yamashita, Y.; Yamada, K.; Zhang, W.; Han, R.;Liu, W.; Tsubomura, T.; Nishihara, H. Coordination NanosheetsBased on Terpyridine−Zinc(II) Complexes: As Photoactive HostMaterials. J. Am. Chem. Soc. 2017, 139 (15), 5359−5366.(43) Liu, Y.; Sakamoto, R.; Ho, C.-L.; Nishihara, H.; Wong, W.-Y.Electrochromic Triphenylamine-Based Cobalt(II) Complex Nano-sheets. J. Mater. Chem. C 2019, 7 (30), 9159−9166.(44) Bera, M. K.; Mori, T.; Yoshida, T.; Ariga, K.; Higuchi, M.Construction of Coordination Nanosheets Based on Tris(2,2′-Bipyridine)−Iron (Fe2+) Complexes as Potential ElectrochromicMaterials. ACS Appl. Mater. Interfaces 2019, 11 (12), 11893−11903.(45) Mondal, S.; Ninomiya, Y.; Yoshida, T.; Mori, T.; Bera, M. K.;Ariga, K.; Higuchi, M. Dual-Branched Dense Hexagonal Fe(II)-BasedCoordination Nanosheets with Red-to-Colorless Electrochromismand Durable Device Fabrication. ACS Appl. Mater. Interfaces 2020, 12(28), 31896−31903.(46) Bera, M. K.; Mohanty, S.; Kashyap, S. S.; Sarmah, S.Electrochromic Coordination Nanosheets: Achievements and FuturePerspective. Coord. Chem. Rev. 2022, 454, No. 214353.(47) Roy, S.; Halder, S.; Chakraborty, C. Dimensional Perspectiveson Metal Center Associated Electrochromism in Metal-OrganicCoordinated Hybrid Polymers: Unveiling Electrochromic Dynamics.Coord. Chem. Rev. 2024, 519, No. 216088.(48) Halder, S.; Chakraborty, C. Evolving Trends in ElectrochromicEnergy Storage Devices: Insights from the Nanoarchitectonics ofMetallo-Supramolecular Polymers. Nano Energy 2024, 131,No. 110243.(49) Roy, S.; Chakraborty, C. Transmissive to Blackish-Green NIRElectrochromism in a Co(II)-Based Interfacial Co-Ordination ThinFilm. Chem. Commun. 2021, 57 (61), 7565−7568.(50) Ou, X.; Gong, D.; Han, C.; Liu, Z.; Tang, Y. Advances andProspects of Dual-Ion Batteries. Adv. Energy Mater. 2021, 11 (46),No. 2102498.(51) Mukkatt, I.; Mohanachandran, A. P.; Nirmala, A.; Patra, D.;Sukumaran, P. A.; Pillai, R. S.; Rakhi, R. B.; Shankar, S.; Ajayaghosh,A. Tunable Capacitive Behavior in Metallopolymer-Based Electro-chromic Thin Film Supercapacitors. ACS Appl. Mater. Interfaces 2022,14 (28), 31900−31910.(52) Halder, S.; Chakraborty, C. Ligand-Engineered Fe(II)-Metallo-Supramolecular Polymer with Benzothiadiazole: Boosting Electro-chromic Energy Storage Efficiency. Chem. Eng. J. 2024, 498,No. 155382.(53) Cai, G.; Chen, J.; Xiong, J.; Lee-Sie Eh, A.; Wang, J.; Higuchi,M.; Lee, P. S. Molecular Level Assembly for High-PerformanceFlexible Electrochromic Energy-Storage Devices. ACS Energy Lett.2020, 5 (4), 1159−1166.(54) Mondal, S.; Yoshida, T.; Maji, S.; Ariga, K.; Higuchi, M.Transparent Supercapacitor Display with Redox-Active Metallo-Supramolecular Polymer Films. ACS Appl. Mater. Interfaces 2020,12 (14), 16342−16349.(55) Mondal, S.; Ninomiya, Y.; Higuchi, M. Durable SupercapatteryFilm with Dual-Branched Dense Hexagonal Fe(II)-Based Coordina-tion Nanosheets for Flexible Power Sources. ACS Appl. Energy Mater.2020, 3 (11), 10653−10659.(56) Cong, B.; Xie, Y.; Wu, Y.; Zhou, H.; Chen, C.; Zhao, X.; Chao,D. Metal-Organic Coordination Polymer Bearing Dual-Redox CentraEnables High-Performance Electrochromic Supercapacitor. Chem.Eng. J. 2023, 474, No. 145528.(57) Wang, H.; Qiu, F.; Lu, C.; Zhu, J.; Ke, C.; Han, S.; Zhuang, X.A Terpyridine-Fe2+-Based Coordination Polymer Film for On-ChipMicro-Supercapacitor with AC Line-Filtering Performance. Polymers2021, 13 (7), No. 1002.(58) Bo, Z.; Cheng, X.; Yang, H.; Guo, X.; Yan, J.; Cen, K.; Han, Z.;Dai, L. Ultrathick MoS2 films with exceptionally high volumetriccapacitance. Adv. Energy Mater. 2022, 12 (11), No. 2103394.(59) Bansal, L.; Sahu, B.; Rath, D. K.; Ahlawat, N.; Ghosh, T.;Kandpal, S.; Kumar, R. Stoichiometrically Optimized ElectrochromicComplex [V2 O2+ξ (OH)3-ξ ] Based Electrode: PrototypeSupercapacitor with Multicolor Indicator. Small 2024, 20 (32),No. 2312215.(60) Bansal, L.; Lübkemann-Warwas, F.; Sahu, B.; Ghosh, T.;Kandpal, S.; Rani, C.; Rath, D. K.; Prawitt, L.; Wesemann, C.; Bigall,N. C.; Kumar, R. Nano Aerogel-Based VIS-NIR SwitchableElectrochromic Supercapacitor: Energy Storage and Heat-ShieldingDevice. ACS Appl. Mater. Interfaces 2025, 17 (21), 31201−31211.(61) Huang, X.; Sheng, P.; Tu, Z.; Zhang, F.; Wang, J.; Geng, H.;Zou, Y.; Di, C.; Yi, Y.; Sun, Y.; Xu, W.; Zhu, D. A Two-Dimensionalπ−d Conjugated Coordination Polymer with Extremely HighElectrical Conductivity and Ambipolar Transport Behaviour. Nat.Commun. 2015, 6 (1), 7408.(62) Chondath, S. K.; Gopinath, J. S.; Poolakkandy, R. R.;Parameswaran, P.; Menamparambath, M. M. Investigations on theInterfacial Tension Induced Self-Assembly in Tuning the 2DMorphology of Polypyrrole at Water/Chloroform Interface. Macro-mol. Mater. Eng. 2022, 307 (2), No. 2100705.(63) Steudel, S.; Myny, K.; Schols, S.; Vicca, P.; Smout, S.; Tripathi,A.; Van Der Putten, B.; Van Der Steen, J.-L.; Van Neer, M.; Schütze,F.; Hild, O. R.; Van Veenendaal, E.; Van Lieshout, P.; Van Mil, M.;Genoe, J.; Gelinck, G.; Heremans, P. Design and Realization of aFlexible QQVGA AMOLED Display with Organic TFTs. Org.Electron. 2012, 13 (9), 1729−1735.(64) Nakajima, Y.; Teranishi, Y.; Kida, Y.; Maki, Y. Ultra-Low-PowerLTPS TFT-LCD Technology Using a Multi-Bit Pixel MemoryCircuit. J. Soc. Inf. Display 2006, 14 (12), 1071.(65) Comiskey, B.; Albert, J. D.; Yoshizawa, H.; Jacobson, J. AnElectrophoretic Ink for All-Printed Reflective Electronic Displays.Nature 1998, 394 (6690), 253−255.(66) Halder, S.; Chakraborty, C. Evolving Trends in ElectrochromicEnergy Storage Devices: Insights from the Nanoarchitectonics ofMetallo-Supramolecular Polymers. Nano Energy 2024, 131,No. 110243.(67) Mondal, S.; Roy, S.; Fujii, Y.; Higuchi, M. Highly DurableElectrochromic Devices for More than 100,000 Cycles with Fe(II)-Based Metallo-Supramolecular Polymer by Optimization of theDevice Conditions. ACS Appl. Electron. Mater. 2023, 5 (12), 6677−6685.(68) Roy, S.; Ganeshan, S. K.; Pal, S.; Chakraborty, C. TargetedEnhancement of Electrochromic Memory in Fe(II) Based Metallo-Supramolecular Polymer Using Molybdenum Disulfide QuantumDots. Sol. Energy Mater. Sol. Cells 2022, 236, No. 111487.ACS Applied Materials & Interfaces www.acsami.org Research Articlehttps://doi.org/10.1021/acsami.5c13795ACS Appl. Mater. Interfaces 2025, 17, 62499−6250962509https://doi.org/10.1016/j.ccr.2024.216004https://doi.org/10.1016/j.ccr.2024.216004https://doi.org/10.1016/j.ccr.2024.216004https://doi.org/10.1002/anie.201100669https://doi.org/10.1002/anie.201100669https://doi.org/10.1021/ja510788b?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/ja510788b?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/cm301194a?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1039/C7SC02688Ahttps://doi.org/10.1039/C7SC02688Ahttps://doi.org/10.1039/C7SC02688Ahttps://doi.org/10.1021/jacs.6b12810?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/jacs.6b12810?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/jacs.6b12810?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1039/C9TC02257Khttps://doi.org/10.1039/C9TC02257Khttps://doi.org/10.1021/acsami.8b22568?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acsami.8b22568?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acsami.8b22568?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acsami.0c05921?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acsami.0c05921?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acsami.0c05921?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1016/j.ccr.2021.214353https://doi.org/10.1016/j.ccr.2021.214353https://doi.org/10.1016/j.ccr.2024.216088https://doi.org/10.1016/j.ccr.2024.216088https://doi.org/10.1016/j.ccr.2024.216088https://doi.org/10.1016/j.nanoen.2024.110243https://doi.org/10.1016/j.nanoen.2024.110243https://doi.org/10.1016/j.nanoen.2024.110243https://doi.org/10.1039/D1CC02815Dhttps://doi.org/10.1039/D1CC02815Dhttps://doi.org/10.1039/D1CC02815Dhttps://doi.org/10.1002/aenm.202102498https://doi.org/10.1002/aenm.202102498https://doi.org/10.1021/acsami.2c05744?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acsami.2c05744?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1016/j.cej.2024.155382https://doi.org/10.1016/j.cej.2024.155382https://doi.org/10.1016/j.cej.2024.155382https://doi.org/10.1021/acsenergylett.0c00245?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acsenergylett.0c00245?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acsami.9b23123?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acsami.9b23123?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acsaem.0c01720?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acsaem.0c01720?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acsaem.0c01720?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1016/j.cej.2023.145528https://doi.org/10.1016/j.cej.2023.145528https://doi.org/10.3390/polym13071002https://doi.org/10.3390/polym13071002https://doi.org/10.1002/aenm.202103394https://doi.org/10.1002/aenm.202103394https://doi.org/10.1002/smll.202312215https://doi.org/10.1002/smll.202312215https://doi.org/10.1002/smll.202312215https://doi.org/10.1021/acsami.4c22928?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acsami.4c22928?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acsami.4c22928?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1038/ncomms8408https://doi.org/10.1038/ncomms8408https://doi.org/10.1038/ncomms8408https://doi.org/10.1002/mame.202100705https://doi.org/10.1002/mame.202100705https://doi.org/10.1002/mame.202100705https://doi.org/10.1016/j.orgel.2012.05.034https://doi.org/10.1016/j.orgel.2012.05.034https://doi.org/10.1889/1.2408388https://doi.org/10.1889/1.2408388https://doi.org/10.1889/1.2408388https://doi.org/10.1038/28349https://doi.org/10.1038/28349https://doi.org/10.1016/j.nanoen.2024.110243https://doi.org/10.1016/j.nanoen.2024.110243https://doi.org/10.1016/j.nanoen.2024.110243https://doi.org/10.1021/acsaelm.3c01143?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acsaelm.3c01143?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acsaelm.3c01143?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1021/acsaelm.3c01143?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-ashttps://doi.org/10.1016/j.solmat.2021.111487https://doi.org/10.1016/j.solmat.2021.111487https://doi.org/10.1016/j.solmat.2021.111487https://doi.org/10.1016/j.solmat.2021.111487www.acsami.org?ref=pdfhttps://doi.org/10.1021/acsami.5c13795?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as