Application In Electrochromic Devices Research Articles

A Transparent to Dark Non‐Complementary Electrochromic Device Based on Al3+ Guest Ions with TMTU/TMFDS2+ Redox Couple for Robust Stability

AbstractAl3+‐based electrochromic devices (ECDs) are expected to substitute Li+‐based ECDs as the next‐generation smart windows options. Compared to Li+, Al3+ possess large quantities in the earth and safety, while the smaller ionic radius and three‐electron redox mechanism can break the capacity bottleneck of inorganic electrochromic materials (ECM). However, limited by the strong electrostatic interaction between Al3+ with ECM and the lack of matching counter electrodes, the research on Al3+ is still focused on three‐electrode system without applications in ECDs. Different from conventional complementary structure, the ECM/redox/CCE (catalytic counter electrode) structure is introduced to enhance the kinetics (from 1.56 × 10−11 to 9.45 × 10−11 cm2 s−1) of the Al3+ intercalation/extraction process. Based on this structure, Al3+‐based ECDs achieve a series of excellent properties: a) almost total absorption of visible and near‐infrared waveband (T500–1500 nm ≈0%) under −1.0 V; b) ultra‐low driving voltage (53% transmittance modulation under −0.1 V); c) excellent memory effect with the presence of redox couple; d) wide range of color modulation capability (yellow, green, blue, and black); e) outstanding energy efficiency. Moreover, the possibility of Na+ as an alternative to Li+ is also verified and Na+‐based ECDs exhibit comparable electrochromic properties to Li+‐based ECDs.

MnO2 nanoparticles advancing electrochemical performance of Ni(OH)2 films for application in electrochromic energy storage devices

In this study, we report a unique material design of interconnected MnO2 nanoparticles covered with a Ni(OH)2 layer as an electrochromic energy storage device. MnO2/Ni(OH)2 electrodes are prepared via sequential electrodeposition within a short duration. During the electrodeposition of Ni(OH)2, the electrodeposited interconnected MnO2 nanoparticles on the substrate provide additional nucleation sites, indicating the porous morphology of the Ni(OH)2 layer without any significant cracks. The synergistic effects generated by the hybrid structure combined with interconnected MnO2 nanoparticles and Ni(OH)2 layer improve the charge transfer kinetics by shortening the transport pathway, facilitating electrochromic performance with fast switching times (2.66 s for bleaching process and 2.72 s for coloring process) and significant transmittance retention. In addition, the energy storage performance of the MnO2/Ni(OH)2 electrode shows an excellent areal capacitance (26.0 mF cm−2 at an operating current density of 0.2 mA cm−2). The electrochromic energy storage device with a two-electrode system (MnO2/Ni(OH)2 as the positive electrode and TiO2 as the negative electrode) exhibits comparable switching times (1.79 s for bleaching time and 3.28 s for coloring time) and areal capacitance (1.21 mF cm−2 at an operating current density of 0.2 mA cm−2) over a wide potential range.

Polyurethane-Based Gel Electrolyte for Application in Flexible Electrochromic Devices.

For the application in flexible electrochromic devices (ECDs) on plastic substrates, a new polyurethane-based gel electrolyte was manufactured. In this context, the curing behavior and the influence of the proportion of solvent and salt on the ion conductivity as well as the optical and mechanical properties were investigated. Furthermore, the stoichiometric ratio of the polyurethane matrix was varied to influence the ion conductivity. As an isocyanate component, the aliphatic difunctional polyisocyanate prepolymer, synthesized by Hexamethylen-1,6-diisocyanat (HDI), was chosen since the resulting polyurethane is considered to be particularly lightfast, color-stable and temperature-resistant and therefore frequently used for paints and coatings. As polyol a trifunctional polyetherpolyol was selected to form a wide-meshed crosslinked matrix to achieve a mechanically stable but flexible electrolyte, that enables the processing and bending of film-based ECDs. The additives amount and the matrix stoichiometric ratio affected the curing behavior and curability. The salt content had almost no influence on the measured properties in the chosen experimental space. Solvent content had a great influence on ion conductivity and mechanical properties. An understoichiometric ratio of the polyurethane matrix (0.85) increases the ion conductivity and the mechanical flexibility, but also the optical properties in a negative manner. The best specific ion conductivity with 10−5 S/cm was reached with an understoichiometric ratio of 0.85 and a high solvent content (30 wt%). Concluding, due to its high flexibility and transmittance, color neutrality and sufficient ion conductivity, the application of the researched electroyte in ECDs might be suitable. A demonstrator ECD was successfully manufactured and conducted.

Preparation of highly adhesive urethane–acrylate-based gel-polymer electrolytes and their optimization in flexible electrochromic devices

Gel-polymer electrolytes are attractive for applications in flexible electrochromic devices (ECDs). Among such electrolytes, UV-curable gel-polymer electrolytes are particularly advantageous because they can be cured in a short time and suffer less deformation from heating due to low-temperature treatment. In this study, we developed a polyurethane-acrylate-based UV-curable gel-polymer electrolyte with excellent adhesion, optical transparency, and high ion conductivity by optimizing the urethane acrylate mixing ratio. The use of urethane acrylate conferred high adhesion to these gel-polymer electrolytes, and an electrolyte with high ion conductivity was developed by optimizing the ratio of urethane acrylate (oligomer) and poly(ethylene glycol) methyl ether methacrylate (monomer). The optical properties of the ECDs fabricated using the optimized electrolytes were compared. In the case of the glass-type ECDs, upon adding 33.2 wt% urethane acrylate, the coloring transmittance was observed to be 8.54%; the bleaching transmittance was 62.96%; and the change in transmittance reached 54.42%. By conducting a switching cycle test for approximately 45 times on a flexible electrochromic device made of indium tin oxide on a polyethylene terephthalate (ITO-PET) film, 43% change in transmittance was confirmed. These gel-polymer electrolytes are expected to be useful for the commercialization of flexible ECDs.

P-doped carbon quantum dot graft-functionalized amorphous WO3 for stable and flexible electrochromic energy-storage devices

The intrinsic structural instability of amorphous WO3 (a-WO3) following repeated Li ion insertion/extraction and bending hinders its application in stable and flexible electrochromic (EC) energy-storage devices. To resolve this problem, developing an elaborate heterostructure of a-WO3 is essential for high-performance flexible EC energy-storage devices. Herein, a novel structure is proposed to introduce P-doped carbon quantum dots (P-CQDs) into a-WO3 through a low-temperature process to induce robust chemical linkages with a-WO3. The functional groups of P-CQDs form strong hydrogen bonds with a-WO3 in the form of quantum dot grafts, which effectively tolerate structural deformation following long, repetitive cycling electrochemical reactions and bending. Moreover, the functional groups and graphitic carbon of P-CQDs improve the Li ion wettability and electrical conductivity, respectively, thereby enhancing the electrochemical activity and kinetics. As a result of the impacts, P-CQD graft-functionalized a-WO3 (P-CQD/a-WO3) electrodes exhibit excellent EC energy-storage performances. Furthermore, a flexible EC energy-storage device fabricated with the P-CQD/a-WO3 electrode exhibits a remarkably enhanced long-term cycle stability (transmittance retention of 87.3% after 4,000 cycles) and flexibility (transmittance retention of 84.1% and specific capacitance retention of 85.3% after 500 bending cycles). Therefore, we believe that the proposed heterostructure-inducing quantum dot graft functionalization with a-WO3 is a breakthrough in the realization of high-performance flexible EC energy-storage devices.

Analysis of structural morphological changes from 3DOM V2O5 film to V2O5 nanorods film and its application in electrochromic device

Nanoscale V 2 O 5 films possess excellent electrochemical properties and have great potential for application in electrochromic devices. Herein, we report a novel strategy for the transformation of three-dimensionally ordered macroporous(3DOM) V 2 O 5 films into V 2 O 5 nanorods film using a simple low-temperature annealing treatment, in which the heterogeneous nucleation sites provided by PS colloidal sphere surface, the anisotropic bonding of V 2 O 5 , atomic rearrangement, and Ostwald ripening are all important factors affecting the morphological transformation. According to this study, during the preparation of 3DOM V 2 O 5 films, a small number of oxygen vacancies were introduced into the V 2 O 5 lattice, and the annealing treatment (250–400 °C, 4–8 h) controlled the concentration of oxygen vacancies. Compared with the ion storage capacity of V 2 O 5 films prepared by conventional sol-gel dip-coating method (17.79 mC cm −2 for unannealed V 2 O 5 films and 13.90 mC cm −2 for V 2 O 5 films after 6 h of annealing at 350 °C), the 350°C-6h films with nanorod structure had the highest ion-storage performance, the initial value raised to 98.77 mC cm −2 . Further, the cycling stability was excellent, with only a 6.1% decrease after 5000 cycles. This was because of the special nanorod structure and the presence of a certain number of gradient oxygen vacancies in the 350°C-6h film. The 350°C-6h film also had good electrochromic properties, a wide range of transmittance modulation (73.6%), and a fast response time (3.2 s for coloring and 3.9 s for bleaching). In addition, electrochromic devices (ECDs) with 350°C-6h films as both ion-storage layers and electrochromic layers have been successfully assembled, which exhibit high performance. • 3DOM V 2 O 5 film was prepared on ITO substrate by Template assistance sol-gel method. • Annealing induced morphology change from 3DOM to nanorods in V 2 O 5 films. • The annealing affects oxygen vacancy concentration, and in turn affects on ion storage capacity. • V 2 O 5 nanorodsfilms presents excellent capacity and cycle performance for lithium storage. • The electrochromic device assembled with V 2 O 5 film showed fascinating performance.

Nebulizer sprayed nickel-manganese (Ni-Mn) mixed metal oxide nanocomposite coatings for high-performance electrochromic device applications

Nebulizer sprayed nickel-manganese (Ni-Mn) mixed metal oxide nanocomposite coatings for high-performance electrochromic device applications

Evaluation of Transparent ITO/Nano-Ag/ITO Electrode Grown on Flexible Electrochromic Devices by Roll-to-Roll Sputtering Technology

This paper explores the flexible ITO/nano-Ag/ITO multilayer electrodes grown on polyethylene terephthalate (PET) substrates and processed by a continuous roll-to-roll (R2R) sputtering system at room temperature used for flexible electrochromic device (ECD) applications. The effect of the nano-Ag interlayer thickness on the electrical and optical properties of the flexible ITO/nano-Ag/ITO multilayer was thoroughly investigated. By using R2R-sputtered at an Ag DC power of 0.2 kW, we were able to achieve optimal ITO/nano-Ag/ITO multilayer that exhibits a high optical transmittance of 87.19% and the best figure of merit value (30.93 × 10−3 Ω−1). The EC performance and stability of the flexible devices were tested by a cathodic WO3 coloration. Coloring and bleaching tests show that ITO/nano-Ag/ITO multilayers are highly effective conductors, indicating that the R2R sputtering technique is a promising continuous sputtering process in preparing for the fabrication of optical devices and flexible electronics industries.

Multipurpose acetic acid functionalized carbazole derivatives: Synthesis, electrochemical properties and electrochromic device applications

• Synthesis of two multifunctional acetic acid functionalized carbazole bearing monomers. • Comparison of electrochemically synthesized polymers in terms optoelectronic behaviors. • Construction and characterization of a prototype P2 and PEDOT bearing solid state electrochromic devices. In this study, synthesis of two multifunctional acetic acid functionalized carbazole bearing monomers; 2-(3,6-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-9H-carbazol-9-yl)acetic acid (M1) and 3,6-dithien-2-yl-9H-carbazol-9-ylaceticacid (M2) via Stille cross-coupling reaction was reported. Obtained monomers were electrochemically polymerized in 0.1 M TBAPF 6 /DCM/ACN (5:95, v:v) solution and characterized in terms of electrochemical, spectroelectrochemical and electrochromic switching behaviors. When poly-2-(3,6-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-9H-carbazol-9-yl)acetic acid (P1) and poly-3,6-dithien-2-yl-9H-carbazol-9-ylaceticacid (P2) were compared in terms of electrochemical behaviors, by virtue of the electron-rich EDOT units in the P1 chains, the polymer film exhibited lower monomer oxidation potential at around 1.05 V. Both polymers exhibited neutral state yellow color with similar optical band gaps and multi-electrochromic behaviors under different applied potentials. Insertion of thiophene unit instead of ethylene dioxythiophene (EDOT) unit on the polymer backbone enhanced the electrochromic and optical contrast properties and P2 showed the higher optical contrast then P1. Furthermore, owing to the promising electrochromic properties of P2 like red shifted absorption and higher optical contrast, a prototype P2 and PEDOT bearing solid state electrochromic devices (ECDs) were constructed and characterized. P2 and PEDOT comprising ECD works between yellow and blue colors at −2.0 V and at 2.0 V respectively, with 41% optical contrast and 1.3 s switching time at 580 nm. Furthermore, P2 was used for energy storage applications before and in the present study it was used for ECD applications with promising results which make acetic acid functionalized carbazole derivatives multi-purpose new generation materials.

High-Properties electrochromic device based on TiO2@Graphene/Prussian blue Core-Shell nanostructures

• A novel TNRA@G/PB core–shell nanostructure has been successfully prepared. • The evolution of PB growth layer were studied by XPS depth profiles. • Excellent performance depends on the porous structure and electron transpor. • A model of K + diffusion and e - transport at the interface was proposed. Herein, the successful preparation of a high-performance electrochromic device (ECD) with the TNRA@G/PB core–shell nanostructure as the electrode has been described. The core–shell nanostructure was formed by wrapping graphene (G) and growing Prussian blue (PB) on the TiO 2 nanorod array (TNRA) through the two-step hydrothermal and spin coating method. The existence state of elemental iron (Fe) and the evolution of the PB growth layer were studied by X-ray photoelectron spectroscopy (XPS) depth profiles. In addition, a model of K + diffusion and electron transport in the ECDs was proposed to explain the mechanism of the enhanced electrochromic property of the TNRA@G/PB core–shell nanostructures. The TNRA as a support template is conducive to electrolyte penetration and rapid ion replenishment to active sites. At the same time, the porous structure can alleviate the volume expansion during the electrical cycle which will increase the cycle stability of ECDs. G acts as a bridge between the conductive and active layer and can reduce the loss of electrons between interfaces in the transport process. It provides a fast transport channel for electrons and promotes the rapid response of electrochromism. Compared with ECDs based on the traditional PB film, TNRA@G/PB core–shell nanostructures achieve a higher optical modulation range (56.1%) and a shorter switching time (t c /t b = 1.0/2.8 s). In particular, the coloration efficiency (CE) has been significantly increased to 129.1 cm 2 /C at a wavelength of 700 nm, which shows a promising application in high-performance ECDs.

Syntheses of novel fluorinated dibenzo[a,c]phenazine comprising polymers for electrochromic device applications

In this study, five novel fluorinated dibenzo[a,c]phenazine comprising polymers were synthesized and characterized for electrochromic device applications.

Electrosynthesis of electrochromic polymers based on bis-(4-(N-carbazolyl)phenyl)-phenylphosphine oxide and 3,4-propylenedioxythiophene derivatives and studies of their applications in high contrast dual type electrochromic devices

Five phenylphosphine oxide-containing polymers (PBCPO (poly(bis-(4-(N-carbazolyl)phenyl)-phenylphosphine oxide)), P(BCPO-co-ProD-Me2), P(BCPO-co-ProD-Et2), P(BCPO-co-ProD-Bz2), and P(BCPO-co-ProD)) are electrodeposited on indium tin oxide (ITO) coated glass slide and their electrochromic performances are characterized. The optical band gap of PBCPO is 3.14 eV. P(BCPO-co-ProD-Bz2) attains a high transmittance change (ΔT = 55% at 740 nm) and shows multicolored electrochromism from light tan (0.0 V), grayish-green (0.4 V), greenish-gray (1.1 V) to deep gray (1.2 V). Electrochromic devices (ECDs) containing phenylphosphine oxide-based polycarbazoles and poly(3,4-ethylenedioxythiophene) (PEDOT) as active electrode layers are constructed. PBCPO/PEDOT ECD displays light gray, gray, and greenish-gray at 0.0, 0.8, and 1.9 V, respectively. P(BCPO-co-ProD-Bz2)/PEDOT ECD displays a high optical contrast (ΔT = 42.5% at 630 nm) and P(BCPO-co-ProD)/PEDOT ECD shows a high coloration efficiency (η = 454.1 cm2•C−1 at 630 nm). In addition, P(BCPO-co-ProD derivatives)/PEDOT ECDs have adequate optical memories and long-term redox cyclic stability.Background: Polycarbazoles can create considerably stable radical cations (polarons) and dications (bipolarons) when increasing potentials or doping chemicals. Moreover, carbazole and phenylphosphine oxide are donor (D) and acceptor (A) units in BCPO, respectively. The incorporation of phenylphosphine oxide in polycarbazoles gives rise to the improvement of charge balances and carrier mobilities. It is interesting to investigate the absorption spectra and multicolored electrochromisms of five phenylphosphine oxide-containing polycarbazoles and their corresponding ECDs upon undergoing a redox process.Methods: A series of phenylphosphine oxide-containing anodic polymers (PBCPO, P(BCPO-co-ProD-Me2), P(BCPO-co-ProD-Et2), P(BCPO-co-ProD-Bz2), and P(BCPO-co-ProD)) are electrodeposited on ITO coated glass. The absorption spectra, color variations, response time, and long-term electrochemical stability of PBCPO/PEDOT, P(BCPO-co-ProD-Me2)/PEDOT, P(BCPO-co-ProD-Et2)/PEDOT, P(BCPO-co-ProD-Bz2)/PEDOT, and P(BCPO-co-ProD)/PEDOT ECDs are investigated comprehensively.Significant findings: The as-prepared phenylphosphine oxide-containing polycarbazoles exhibit multicolored electrochromism and high transmittance change (ΔT = 55% at 740 nm), which provide new structural insights to develop new generation electrochromic electrodes.

Nanoengineering of poly(3,4-ethylenedioxythiophene) for boosting electrochemical applications

As one of the most promising conducting polymers, poly(3,4-ethylenedioxythiophene) (PEDOT) has attracted significant interests in electrochemical applications such as energy storage and electrochromism. However, the intrinsic PEDOT having a dense structure usually exhibits unsatisfactory electrochemical performance such as low charge storage capacity and optical modulation behavior, which limits their applications in supercapacitors and electrochromic devices. In this case, nanoengineering provides an effective strategy to improve the electrochemical performance by optimizing the conjugated structure of PEDOT. Herein, comprehensive reviews and discussions are conducted to demonstrate the nanoengineering of PEDOT for boosting the electrochemical applications. The advantages and shortcomings of PEDOT are discussed firstly, and thus introducing the necessary of nanoengineering for optimizing the electrochemical performance. Some strategies of nanoengineering are summarized according to the classification of physical and chemical methods. Then, the latest advances and progresses are reviewed in detail concerning the applications of nanoengineered PEDOT in supercapacitors and electrochromic devices. Finally, some challenges and prospects are proposed to show the further development of nanoengineering of advanced PEDOT materials and devices. We anticipate that this review will spark new ideas for the construction of high-performance PEDOT towards developing advanced electrochemical devices.

Enhanced adhesion of Ag nanowire based transparent conducting electrodes for application in flexible electrochromic devices

Silver nanowires (Ag NWs) are currently the most likely to replace indium tin oxide (ITO) as flexible transparent conducting electrodes (FTCEs), but conventional preparation methods such as solution deposition will lead to weak conductivity and low adhesion to the substrate. In this work, polymethyl methacrylate (PMMA) as a superior mediate for the pressure embedding of Ag NW networks as transparent electrodes with 120 °C is demonstrated. The sheet resistance of the PMMA/Ag NWs FTCEs decreases from 32 Ω/sq. to 8.1 Ω/sq. at an optical transmittance of ~77.5 %. The calculated value of figures of merit ( FoM )is as high as 9.77 × 10 −3 Ω −1 . At the same time, after 10 min of ultrasonication and 30 times of wiping cycle, the sheet resistance is almost unchanged, indicating that the Ag NW networks have good adhesion to the flexible substrate. Meanwhile, the PMMA/Ag NWs FTCEs exhibit good mechanical flexibility with a bending radius up to 0.75 mm. Finally, the successful implementation of the PMMA/Ag NWs FTCEs into a flexible electrochromic device is demonstrated, verifying the applicability of PMMA/Ag NWs FTCEs. • High-reliable PMMA/AgNW FTCEs are obtained by hot lamination process. • PMMA/AgNW FTCEs show simultaneously improved conductivity and adhesion. • Resistance does not show significant change after ultrasonication and wiping test. • Flexible electrochromic device based on FTCEs is prepared and demonstrated.

Synthesis of a highly conductive organic-inorganic hybrid gel electrolyte and its characterization and application in electrochromic devices

Synthesis of a highly conductive organic-inorganic hybrid gel electrolyte and its characterization and application in electrochromic devices

Electrochromic Performance and Capacitor Performance of α-MoO3 Nanorods Fabricated by a One-Step Procedure

In this paper, we propose for the first time the synthesis of α-MoO3 nanorods in a one-step procedure at mild temperatures. By changing the growth parameters, the microstructure and controllable morphology of the resulting products can be customized. The average diameter of the as-prepared nanorods is about 200 nm. The electrochromic and capacitance properties of the synthesized products were studied. The results show that the electrochromic properties of α-MoO3 nanorods at 550 nm have 67% high transmission contrast, good cycle stability and fast response time. The MoO3 nanorods also exhibit a stable supercapacitor performance with 98.5% capacitance retention after 10,000 cycles. Although current density varies sequentially, the nanostructure always exhibits a stable capacitor to maintain 100%. These results indicate the as-prepared MoO3 nanorods may be good candidates for applications in electrochromic devices and supercapacitors.

Stretchable electrochromic devices based on embedded WO3@AgNW Core-Shell nanowire elastic conductors

Stretchable electrochromic devices (SECDs) have steadily attracted widespread attention in wearable devices. However, the delamination of device architectures (electrochromic layer, conductive layer and substrate) and poor chemical stability of conductive layer (silver nanowires (AgNWs)) are the key issues to be resolved to ensure the practical applications of flexible electrochromic devices. Herein, we designed a flexible and stretchable WO3@AgNW-PrePDMS (Pre-cured Polydimethylsiloxane) electrode, through integrated and embedded design, to build a high-performance electrochromic device. The integration of electrochromic layer and conductive layer in the electrode is fabricated via a WO3@AgNW core–shell structure. And embed the core–shell structure into the flexible substrate PDMS to form WO3@AgNW-PrePDMS electrode. This electrode architecture can prevent the delamination of the stretchable electrode during bending tests. Moreover, WO3 as a shell structure protects the conductive material AgNW to prevent its oxidation and improve the stability of the conductive substrate. The WO3@AgNW-PrePDMS electrode displays outstanding electrochemical stabilities and excellent bi-functionalities (flexible conductive film and electrochromic electrode): high conductivity (12 Ω/sq) as flexible transparent conductive film and wide optical modulation range (ΔT = 72% at 550 nm) as electrochromic electrode. The stretchable WO3@AgNW-PrePDMS electrode can still maintain stable electrical conductivity (ΔR/R≈8.3% and 14%) and electrochromic performance (90% and 92% retention) after 20,000 bending cycles and stretching to 70%, indicating the excellent mechanical flexibility. The WO3@AgNW core–shell nanowire network electrodes with embedded structures can be a strong candidate for wearable electrochemical energy devices in the future.

Adhesive electrochromic WO3 thin films fabricated using a WO3 nanoparticle-based ink

Nanotechnology has advanced rapidly in recent years, mainly due to the unique properties of basic elements, which can be tuned by altering their chemical composition and size. Owing to their unique properties, nanoparticles (NPs) are applied in many fields, such as catalysis, electronics, and coatings. In this study, we synthesized a coatable WO3 NP dispersed ink and aimed to highlight the importance of developing an appropriate design strategy for achieving optimal physicochemical properties of the inks. Polyvinyl alcohol (PVA) was added to the WO3 NP ink to improve its adhesion to indium tin oxide-coated glass substrates. The contact angle of the inks on the substrate decreased with the addition of PVA, indicating their good wettability. Furthermore, the WO3 NP films exhibited an excellent transmittance change of 77 % at 633 nm and a coloration efficiency of 35 cm2/C. Their optical transmittance in the visible and near-infrared regions varied with the applied voltage, indicating their potential for applications in electrochromic devices and smart windows.

Molybdenum doping effect on sol-gel Nb2O5:Li+ thin films: Investigation of structural, optical and electrochromic properties

Niobium pentoxide (Nb2O5) has attracted interest in the field of electrochromic devices because of its thermodynamic and chemical stability. However, its performance can be improved by doping with other transition metals or lithium salts, which leads to a change in its crystalline structure and properties. This work describes a study of the influence of molybdenum (Mo) doping on thin films of Nb2O5:Li+ properties. It was observed that the Mo dopant enhanced the cycling stability and reversibility of Nb2O5:Li+ films. The X-ray diffraction (XRD) pointed that the incorporation of the dopant leads to the mixture of the crystalline phases, monoclinic LiNb3O8 and orthorhombic T-Nb2O5. The addition of 7.5 mol% of Mo increased the charge density to 24.5 mC cm-2, ionic conductivity to 1.95 × 10-7 S cm-1, and the reversibility to 95% after 50 color/bleaching cycles. The color change at 500 nm was from 84 to 34%, and the scanning electronic microscopy (SEM) revealed homogeneous and mostly flat surface. The atomic force microscopy (AFM) showed the samples’ surface roughness rising from 0.49 for undoped to 1.15 nm for 7.5 mol% Mo doped film. All collected results suggest that doping improved the performance of Nb2O5:Li+ thin films over cycles, an important property for application in electrochromic devices.

One - Step Green Synthesis of V2O5 and VO2 Using Extract of Orange Peel: Effect of Calcination Atmosphere

In this work two vanadium oxides (V2O5 and VO2) were prepared by green synthesis method using ammonium vanadate (NH4VO3) and extract of orange peel. V2O5 and VO2 have various applications in lithium-ion battery, sensors, transistors, photo catalysis, supercapacitors and electrochromic devices. The effect of calcination atmosphere is obvious as calcination the precursor of (NH4VO3) and extract of orange peel in air at 450? yielded V2O5 while calcination in vacuum at the same temperature gave the reduced form VO2 as estimated by X-ray powder diffraction (XRD). These two different phases of vanadium oxides have different morphologies. Investigation by transmission electron microscope revealed that V2O5 oxide which synthesized in air at 450? showed big particles with laminar shape. The particles look arranged layer over layer with sizes exceed 200 nm. While images of VO2 prepared in vacuum at the same temperature showed different shape and size for their particles. The neutral atmosphere provided by vacuum not only gives reduced form of vanadium oxide (VO2) but also minimizes and changes their particles size and shape, respectively. Unidentified shape of nano sized particles were observed for this reduced oxide. These particles have sizes less than 100 nm and much lower than those observed for V2O5 particles.