Systematic compositional engineering of v 2o 5 based multicolored electrochromic films and device fabrication thereof

Abstract

The present invention relates to systematic compositional engineering of V2O5 based multicolored electrochromic films with polyaniline (PANI) and NiO and device fabrication thereof. More particularly, present invention provides two-way modification of the base metal oxide by co¬ incorporation of a metal cation and a conjugated polymer, which resulted into an excellent improvement in the optical contrast, switching response and cyclic stability of the electrochromic device fabricated thereof.

Description

[0001] P_W0100793

[0002] SYSTEMATIC COMPOSITIONAL ENGINEERING OF V2O5 BASED MULTICOLORED ELECTROCHROMIC FILMS AND DEVICE FABRICATION THEREOF

[0003] FIELD OF INVENTION

[0004] The present invention relates to systematic compositional engineering of V2O5 based multicolored electrochromic films with polyaniline (PANI) and NiO and device fabrication thereof. More particularly, present invention provides two-way modification of the base metal oxide by coincorporation of a metal cation and a conjugated polymer, which resulted into multi-coloured electrochromic films fabricated device having excellent optical contrast, switching response and cyclic stability.

[0005] BACKGROUND OF INVENTION

[0006] Functional materials have acquired enormous recognition in this day and age for storage systems in the framework of batteries, supercapacitors, different color changing devices, etc. Futuristic electronics demand multiple color switchable smart chromic materials, emerging various application areas like, smart displays, smart windows, smart clothes having adapting camouflage features and a lot more. Multichromics are the electrochromic materials which change colors to multiple folds on tuning the external voltage. This is due to several redox reactions that take place on different voltages, leading to various oxidation states and thereby manifestation of different colors. Multichromic materials have widespread application scope over the areas of adaptive camouflages, multicommand display devices and many more which could replace the existing LED / LCD devices in near future. The main contenders of the multicolored electrochromic materials are the conjugated polymers, metallo-supramolecular complexes, and inorganic transition metal oxides having variable valency. Nevertheless, regarding real-time commercialization, conjugated polymers and metal coordination complexes due to some of their intrinsic drawbacks, such as poor performance with respect to long term cyclic stability and slower switching response owing to their imperceptive redox kinetics, are still running behind their nearest competitor the inorganic transition metal oxides. On the other spectrum, the transition metal oxides, on account of their encouraging features, are still winning the race over the other two categories in terms of stability, and optical performance. Vanadium pentoxide, on accountP_W0100793

[0007] of its variable oxidation states, has an excellent ability to show multichromism along with its good charge-storing capacity, which thrives it to use as ultra-competent for multicommand applications. However, this metal oxide in spite of its intriguing features is also accompanied by some of its collateral drawbacks, such as longer switching time, poor optical contrast, and undesirably low electrochemical stability. Till date investigations have addressed any one of two major reasons behind the degrading performance of V2O5 either the shorter distance between successive VOe linkages inside the V2O5 layered structure, or poor electrical conductivity compromising the other cause. To the best of our knowledge, no studies have focused so far on attaining a bilateral remodeling of V2O5 in the same process pathway, that too by employing a facile route of synthesis, which will also be encouraging from the perspective of commercialization.

[0008] Reference may be made to Electrochromic device Nippon Oil Co. Ltd, JP, 1999, US5859722A, wherein, an EC device was fabricated comprising a pair of electrically conductive counter plates, an ion conductive material, an electrochromic material layer, electrolyte protective layer, first and second current spreading layer, a transparent substrate and a transparent electrode disposed inside the transparent substrate, and an ultraviolet absorber layer with a resin material. The drawbacks are, it did not concern about the multi-coloured behaviour of vanadium oxide based electrochromic films and its modification thereof.

[0009] Reference may be made to Electrochromic device Nippon Oil Co. Ltd, JP, 1998, EP855615A2, wherein, an EC device was fabricated comprising a pair of electrically conductive counter plates, an ion conductive material, an electrochromic material layer, electrolyte protective layer, first and second current spreading layer, a transparent substrate and a transparent electrode disposed inside the transparent substrate, and an ultraviolet absorber layer comprising of a combination of organic materials. The drawbacks are, it did not focus on the multi-coloured electrochromic films based on vanadium oxide and its bimodal composition modification thereof.

[0010] Reference may be made to (Electrochromic device with low resistance transparent electrode structure, Swiss Co. Ltd., KR, 2022, JP2022549082A) wherein, has disclosed the use of composite layers as both the electrochromic and counter electrode layer combining of AZO, ITO and FTO along with a metal based layer which are made of either Ag based nanowire or PEDOT:PSS or graphene or metal mesh. The drawbacks are, it did not discuss the electrochromic composition made of vanadium oxide and also its existing challenges to be overcome.P_W0100793

[0011] Reference may be made to Polyaniline based electrochromic fabric and manufacturing method thereof, The Quartermaster Equipment Research Institute PLA General Logistics Department, CN, 2016, CN103257501B, wherein, disclosed the gel electrolyte layer for EC fabric comprising lithium perchlorate, mixture of methyl acrylate and propylene carbonate, ethylene carbonate and polymethacrylate. The drawbacks are, it did not discuss the synergistic modification route of vanadium oxide for remodelling the existing drawbacks of it.

[0012] Reference may be made to Asma Aamir, Adil Ahmad, Said Karim Shah, Noor ul Ain, Mazhar Mehmood, Yaqoob Khan & Zia ur Rehman Electro-codeposition of V2Os-polyaniline composite on Ni foam as an electrode for supercapacitor 31(2020)21035-21045. https: / / doi.org / 10.1007 / sl0854-020-04616-9, wherein, V2O5-PANI composite with Ni foam as a working electrode, Saturated Calomel Electrode (SCE) as a reference electrode and graphite rod as a counter electrode. The drawbacks are, the non-patent material did not focus on the synergistic modification of optical contrast by enhancing the conductivity of metal oxide via doping with NiO and modification of color switching response by the enlargement of layered structure of V2O5 by insertion of PANI inside the layers.

[0013] Reference may be made to Elidia M. Guerra, Mirela C. Santos & Rodrigo F. Bianchi. Chemical Treatment Influence on the Glass Substrate to the Growth of V2O5 / PANI MRS Online Proceedings Library 1230(2009) 607. https: / / doi.org / 10.1557 / PRGC-1230-MM06-07, wherein, the glass substrates were cleaned and treated with UV / ozone treatment and cationic surfactants such as cetyl pyridinium chloride (CPC) and CT AB; and then glass substrates were immersed into the V2O5 / PANI suspension by dip-coating and dried at room temperature. The drawbacks are, the study explored a promising application of PANI intercalated V20s,in ammonia sensing and applications other than electrochromic field.

[0014] Reference may be made to Y.-S. Lin, P.W. Chen, D.J. Lin (Electrochromic performance of NiVxOy thin films deposited onto flexible PET / 1TO substrates by reactive plasma sputtering for flexible electrochromic devicesThin Solid Films 518 (2010) 7416-7420. https: / / doi.Org / 10.1016 / j.tsf.2010.05.004, wherein, plasma sputtered nickel-vanadium oxide film was deposited on a flexible polyethylene terepthalate substrate for electrochromic application. The drawbacks are, incorporation of nickel inside V2Osworked on to enhance the optical contrast than the pristine film, however, the poor electrochemical cyclic stability implied that, a second step ofP_W0100793

[0015] modification was necessary which would act on to increase the layer spacing of V2O5 and thereby result into a larger ion movement pathway, which would facilitate a better stability.

[0016] Thus, keeping in view the drawbacks of the hitherto reported prior arts, the present invention relates to systematic compositional engineering of V2O5 based multi-coloured electrochromic films with polyaniline (PANI) and NiO and device fabrication thereof. More particularly, present invention provides two-way modification of the base metal oxide by co -incorporation of a metal cation and a conjugated polymer, which resulted into an excellent improvement in the optical contrast, switching response and cyclic stability of the electrochromic device fabricated thereof.

[0017] OBJECTIVES OF THE INVENTION:

[0018] Main object of the present invention is to systematic compositional engineering of V2O5 based multicolored electrochromic films with polyaniline (PANI) and NiO and device fabrication thereof.

[0019] Another object is to development of V2O5 based multi-coloured electrochromic films with polyaniline (PANI) and NiO to fabricate a two-electrode electrochromic assembly device.

[0020] Yet another object of the invention is to provide the fabrication of electrochromic window glass and multi-command display by engineering of V2O5 based multi-coloured electrochromic films with polyaniline (PANI) and NiO.

[0021] Yet another object is to provide a multicolor showing electrochromic material with an optical contrast of 75 ±2 %.

[0022] Yet another object is to provide a fabrication method of a two-electrode multicolored electrochromic device thereof.

[0023] Still another object is to provide a faster color switching response, i.e. coloration time (tc) 2.4±0.5 s and bleaching time (tb)2.5±0.5 s of the fabricated multicolored EC device thereof.

[0024] SUMMARY OF THE INVENTION

[0025] Additional features and embodiments of the present disclosure will be better understood through the techniques and other aspects of the disclosure. Other embodiments of the invention are described in detail herein and are considered a part of the claimed disclosure.

[0026] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description section. This summary is not intended to identify keyP_W0100793

[0027] features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[0028] The following is a condensed description of the disclosure to give the reader with a basic understanding. Its main goal is to present some of the principles described in this document in a simpler version as a prologue to the more extensive exposition that follows.

[0029] The present invention, and in accordance with main aspect of the present invention provide a systematic compositional engineering of V2O5 based multicolored electrochromic films with polyaniline (PANI) and NiO and device fabrication thereof which comprises of a unique composition of V2O5 based electrochromic film, wherein a two sided modification of the metal oxide is done by the incorporation of Ni (II) and polyaniline (PANI) in the layered structure of vanadium oxide, which is used for fabrication of EC device prototype by sandwiching a five layered structure, consisting of ITO (Indium tin oxide) coated glass / prepared EC film with optimized composition / transparent free standing Li+based solid gel polymer electrolyte / Ionstorage layer / ITO coated glass for obtaining coloration from yellow to green to grey to red and it resulted in the maximum optical contrast of 75±2% between colored and bleached state tuning the external voltage from -1.5 V to 1.5 V and vice versa.

[0030] Another aspect of the present invention is to provide a process for preparation of nickel oxide (NiO) incorporated vanadium oxide (V2O5) sols, comprising the steps of:

[0031] a. mixing NiO and hydrated V2O5 powders in a ratio of 0.005: 1, followed by grinding the mixture for 30 minutes in an agate mortar;

[0032] b. transferring the mixture into a glass beaker, adding 4 wt. % hexadecyltrimethylammonium bromide (CTAB), 10 wt. % aqueous polyvinyl pyrrolidone (PVP), and ethanol as a solvent, and ultrasonically treating the mixture for 45 minutes;

[0033] c. stirring the resultant solution for 24 hours and aging it for an additional 72 hours to obtain NiO incorporated V2O5 sols.

[0034] Another aspect of the present invention is to provide a process for depositing NiO incorporated V2O5 sols on indium tin oxide (ITO) coated glass substrates, comprising the steps of:

[0035] a. cleaning ITO-coated glass substrates with soap water, deionized water, and ethanol;

[0036] b. dip-coating the cleaned substrates in the NiO incorporated V2O5 sols at a dipping speed of 20 cm / min, holding the substrates in the solution for 1 minute, and withdrawing the substrates at a speed of 10 cm / min;P_W0100793

[0037] c. drying the coated films at 60 °C for 2 hours;

[0038] d. heating the dried films at 350°C with a heating rate of 3°C / min, holding at 350°C for 3 hours, and cooling at a rate of 3°C / min.

[0039] Another aspect of the present invention is to provide a process for preparation of NiO and polyaniline co-incorporated V2O5 sols, comprising the steps of:

[0040] a. mixing NiO, polyaniline, and hydrated V2O5 powders in a ratio of 0.01:0.01:1, followed by grinding the mixture for 30 minutes in an agate mortar;

[0041] b. transferring the mixture into a glass beaker, adding 4 wt. % hexadecyltrimethylammonium bromide (CTAB), 10 wt. % aqueous polyvinyl pyrrolidone (PVP), and ethanol as a solvent, and ultrasonically treating the mixture for 45 minutes;

[0042] c. stirring the resultant solution for 24 hours and aging it for an additional 72 hours to obtain NiO and polyaniline co-incorporated V2O5 sols.

[0043] Another aspect of the present invention is to provide a process for depositing NiO and polyaniline co-incorporated V2O5 sols on indium tin oxide (ITO) coated glass substrates, comprising the steps of:

[0044] a. cleaning ITO-coated glass substrates with soap water, deionized water, and ethanol;

[0045] b. dip-coating the cleaned substrates in the NiO and polyaniline co-incorporated V2O5 sols at a dipping speed of 20 cm / min, holding the substrates in the solution for 1 minute, and withdrawing the substrates at a speed of 10 cm / min;

[0046] c. drying the coated films at 60°C for 2 hours;

[0047] d. heating the dried films at 350°C with a heating rate of 3°C / min, holding at 350°C for 3 hours, and cooling at a rate of 3°C / min.

[0048] Another aspect of the present invention is to provide a fabrication a two-electrode electrochromic assembly device, comprising the step of:

[0049] a. working electrode comprising ITO glass coated with NiO incorporated V2O5 or ITO glass coated with NiO and polyaniline co-incorporated V2O5 electrochromic films;

[0050] b. counter electrode comprising ITO glass coated with NiO as the ion storage layer;

[0051] c. electrolyte comprising a solid gel polymer electrolyte prepared from lithium perchlorate (IJCIO4) as the conducting ion material, propylene carbonate (PC) as a plasticizer, polymethyl methacrylate (PMMA) as a polymer matrix, and tetrahydrofuran (THF) as a solvent;P_W0100793

[0052] d. sandwiching the 1 wt % NiO - 5 wt% PANI-V2O5 coated working electrode between the Li- based solid-gel electrolyte sheet / NiO / ITO counter electrode and leaving no space between the two electrodes;

[0053] Yet another aspect of the present invention is to provide a solid gel polymer electrolyte having composition of 10-20 wt. % LiC104, 40-50 wt. % PC, 20-30 wt. % PMMA, and 5-15 wt. % THF. Yet another aspect of the present invention is to provide faster switching kinetics having a coloration time of (tc) 2.4±0.5 s and a bleaching time (tb) 2.5±0.5 s of the EC prototype.

[0054] Yet another aspect of the present invention is to provide a better electrochemical cyclic stability of 10000 cycles of the electrochromic assembly device prototype.

[0055] BRIEF DESCRIPTION OF THE DRAWINGS

[0056] The present invention is illustrated in figure 1 to 8 of the drawings accompanying this specification.

[0057] FIG.l: Flow Chart illustrating steps involved for single step direct plasma conversion of CO2 to solid carbon

[0058] FIG.2 illustrating Schematic representation of three step synthesis pathway preceded by dipcoating,

[0059] FIG.3 (a)- illustrating of the structural change accompanying enlargement of layered structure of V2O5 after NiO-polyaniline [PANI] co-incorporation, (b) change in band structure occurring after composition remodeling,

[0060] FIG.4 represents the Bright Field Transmission Electron Microscopic (BFTEM) images of (a) pristine V2O5(V), (b) 1 wt% NiO- V2O5(VN1) and (c) 1 wt % NiO- 5 wt% PANI- V2O5(VN1P5), High Resolution Transmission Electron Microscopy (HRTEM) image of (d) pristine V2O5 and (e) 1 wt % NiO- 5 wt% PANI- V2O5 (inset: SAED patterns) (f) EDAX of 1 wt % NiO- 5 wt% PANI-V2O5

[0061] FIG.5 represents the core level X-ray Photoelectron Spectroscopy (XPS) of V2p- (a) typical 1 wt % NiO- 5 wt% PANI- V2O5 , (b) Ni2p of V2N1P5, (c) Ols of VN1P5, (d) Cis VN1P5 FIG.6 represents the Cyclic voltammetry study of (a) pristine V2O5, (b) NiO (with varying composition 0.5, 1, 2 wt %) incorporated V2O5, (c)l wt % NiO- PANI (1, 3, 5, 7 wt %)- V2O5 FIG.7 represents the optical contrast and the switching response of % transmission as a function of time (a) pristine V2O5 (V), (b) 1 wt% NiO- V2O5 (VN1) and (c) 1 wt % NiO- 5 wt% PANI-V2O5 (VN1P5)P_W0100793

[0062] FIG.8 represents the optical and electrochemical cyclic stability after 10000 redox cycles of a typical 1 wt % NiO- 5 wt% PANI incorporated V2O5 sample.

[0063] FIG.9 represents the pictorial representation of multicolored electrochromic system under three electrode assembly condition.

[0064] LIST OF ABBREVIATIONS USED IN THE PRESENT INVENTION PANI- Polyaniline

[0065] DETAILED DESCRIPTION OF THE INVENTION:

[0066] Accordingly, present invention provides an provide systematic compositional engineering of Vanadium pentoxide (V2O5) based multicolored electrochromic films with polyaniline (PANI) and nickel oxide (NiO) and device fabrication thereof.

[0067] In embodiment of the present invention is to provide a process for preparation of nickel oxide (NiO) incorporated vanadium oxide (V2O5) sols, comprising the steps of:

[0068] a. mixing NiO and hydrated V2O5 powders in a ratio of 0.005: 1, followed by grinding the mixture for 30 minutes in an agate mortar;

[0069] b. transferring the mixture into a glass beaker, adding 4 wt. % hexadecyltrimethylammonium bromide (CTAB), 10 wt. % aqueous polyvinyl pyrrolidone (PVP), and ethanol as a solvent, and ultrasonically treating the mixture for 45 minutes;

[0070] c. Stirring the resultant solution for 24 hours and aging it for an additional 72 hours to obtain NiO incorporated V2O5 sols.

[0071] In embodiment of the present invention is to provide a process for depositing NiO incorporated V2O5 sols on indium tin oxide (ITO) coated glass substrates, comprising the steps of:

[0072] a. cleaning ITO-coated glass substrates with soap water, deionized water, and ethanol;

[0073] b. dip-coating the cleaned substrates in the NiO incorporated V2O5 sols at a dipping speed of 20 cm / min, holding the substrates in the solution for 1 minute, and withdrawing the substrates at a speed of 10 cm / min;

[0074] c. drying the coated films at 60°C for 2 hours;

[0075] d. heating the dried films at 350°C with a heating rate of 3°C / min, holding at 350°C for 3 hours, and cooling at a rate of 3°C / min.P_W0100793

[0076] In embodiment of the present invention is to provide a process for preparation of NiO and polyaniline co-incorporated V2O5 sols, comprising the steps of:

[0077] a. mixing NiO, polyaniline, and hydrated V2O5 powders in a ratio of 0.01:0.01:1, followed by grinding the mixture for 30 minutes in an agate mortar;

[0078] b. transferring the mixture into a glass beaker, adding 4 wt. % hexadecyltrimethylammonium bromide (CTAB), 10 wt. % aqueous polyvinyl pyrrolidone (PVP), and ethanol as a solvent, and ultrasonically treating the mixture for 45 minutes;

[0079] c. stirring the resultant solution for 24 hours and aging it for an additional 72 hours to obtain NiO and polyaniline co-incorporated V2O5 sols.

[0080] In embodiment of the present invention is to provide a process for depositing NiO and polyaniline co-incorporated V2O5 sols on indium tin oxide (ITO) coated glass substrates, comprising the steps of:

[0081] a. cleaning ITO-coated glass substrates with soap water, deionized water, and ethanol;

[0082] b. dip-coating the cleaned substrates in the NiO and polyaniline co-incorporated V2O5 sols at a dipping speed of 20 cm / min, holding the substrates in the solution for 1 minute, and withdrawing the substrates at a speed of 10 cm / min;

[0083] c. drying the coated films at 60°C for 2 hours; d. Heating the dried films at 350°C with a heating rate of 3°C / min, holding at 350°C for 3 hours, and cooling at a rate of 3°C / min.

[0084] In embodiment of the present invention is to provide fabrication a two-electrode electrochromic assembly device, comprising the step of:

[0085] a. working electrode comprising ITO glass coated with NiO incorporated V2O5 or ITO glass coated with Ni and polyaniline co-incorporated V2O5 electrochromic films;

[0086] b. counter electrode comprising ITO glass coated with NiO as the ion storage layer;

[0087] c. electrolyte comprising a solid gel polymer electrolyte prepared from lithium perchlorate (LiC104) as the conducting ion material, propylene carbonate (PC) as a plasticizer, polymethyl methacrylate (PMMA) as a polymer matrix, and tetrahydrofuran (THF) as a solvent.

[0088] In embodiment of the present invention is to provide solid gel polymer electrolyte having composition of 10-20 wt. % LiC104, 40-50 wt. % PC, 20-30 wt. % PMMA, and 5-15 wt. % THF. In embodiment of the present invention is to provide faster switching kinetics having a coloration time of (tc) 2.4±0.5 s and a bleaching time (tb) 2.5±0.5 s of the EC prototype.P_W0100793

[0089] The pristine V2O5 solution was obtained by polyol followed by sol-gel synthetic route. 1.67 g of ammonium metavanadate (NH4VO3) and 8 mL of acetic acid (CH3COOH) were subsequently added to 100 ml ethylene glycol [(COOH)2] taken into a round bottom flask, and the mixture was stirred for 30 min. The round bottom flask containing the mixture, then fitted with a reflux condenser and was heated at 170±5°C for 3 h with continuous stirring speed of 250 rpm. After 3 h the resulting mixture was filtered and washed with ethanol-water solution, in order to remove the unreacted ethylene glycol (EG) from the reaction mixture. The obtained precipitate was dried at 80±5°C and was used to prepare the pristine sol of vanadium oxide. A measured quantity of hydrated vanadium oxide (V2O5.XH2O) powder (0.6 g) was taken into a beaker, and to this optimum quantities of N,N,N-cetyltrimethylammonium bromide (CT AB) (0.02 g), and polyvinyl pyrrolidone (PVP) (0.05 ml) were added. A required quantity of ethanol (C2H5OH) (30 ml) was added to it. The mixture was ultrasonicated for 45 mins in order to ensure proper dispersion of the precursor salts and then it was stirred ~ 24 h for uniform mixing and forming a homogeneous transparent solution. After 24 h, the solution was kept undisturbed for 72 h so as to give sufficient time for ageing. After 72 h, the sol of pristine V2O5 formed was used for dip-coating on ITO coated glass substrate.

[0090] In embodiment of the present invention is to provide a process, wherein composition remodeling was obtained by insertion of polyaniline and NiO which were prepared using the conventional condensation polymerization and precipitation technique respectively.

[0091] The NiO solution was prepared using a simple precipitation method. At first, 1 (M) aqueous solution of nickel nitrate hexahydrate [Ni(NO3)2.6H2O] was prepared and subsequently a 1 (M) aqueous solution of NaOH was added drop-wise to it for maintaining the pH of the solution ~ 10. The solution was then kept in standing condition overnight, to complete the precipitation. Accordingly, the precipitate was washed with de-ionized water to remove the excess NaOH, then dried and heat treated at 270±5°C for 3 h with a heating rate of 5°C / min. The black colored powder thus formed was used for the preparation of NiO incorporated V2O5 sol. A measured quantity of hydrated vanadium oxide (V2O5.XH2O) powder (0.6 g) was mixed with NiO powder, and to this optimum quantities of N,N,N-cetyltrimethylammonium bromide (CT AB) (0.02 g), and polyvinyl pyrrolidone (PVP) (0.05 ml) were added. A required quantity of ethanol (C2H5OH) (30 ml) was added to it. The mixture was ultrasonicated for 45 mins in order to ensure proper dispersion of the precursor salts and then it was stirred 24 h for uniform mixing and forming a homogeneousP_W0100793

[0092] transparent solution. After 24 h, the solution was kept undisturbed for 72 h so as to give sufficient time for ageing. After 72 h, the sol of NiO incorporated V2O5 formed, which was used for dipcoating on ITO coated glass substrate.

[0093] Polyaniline powder was prepared by adding 3 ml of aniline with 100 ml of concentrated HC1 and stirring for 2-3 mins in ice bath. After 2-3 mins ammonium persulfate dissolved in H2O was added drop wise until complete oxidation. The stirring was continued for ~ 3 h. After this the solution was kept in standing condition for overnight and then filtered, washed and dried at 70±5°C. The obtained powder was used for preparation of NiO-PANI co-incorporated V2O5 sol of different concentration. A measured quantity of hydrated vanadium oxide (V2O5.XH2O) powder (0.6 g) was mixed with synthesized NiO and polyaniline (PANI)powder, and to this optimum quantities of N, N, N-cetyltrimethylammonium bromide (CT AB) (0.02 g), and polyvinyl pyrrolidone (PVP) (0.05 ml) were added. A required quantity of ethanol (C2H5OH) was added to it. The mixture was ultrasonicated for 45 mins in order to ensure proper dispersion of the precursor salts and then it was stirred for 24 h in order for uniform mixing and forming a homogeneous transparent solution. After 24 h, the solution was kept undisturbed for 72 h so as to give sufficient time for ageing. After 72 h, the sol of NiO-PANI co-incorporated V2Osformed was used for dip-coating on ITO coated glass substrate.

[0094] Initially, three different concentrations (0.5, 1, 2 wt % NiO of V2O5 concentration) of NiO incorporated V2O5 sols were synthesized. The coating was done employing the technique mentioned earlier. The composition was optimized with respect to their cyclic voltammetry curve. A typical NiO-V2Os composition was further used for the preparation of NiO-PANI coincorporated V2O5 with a varying concentration of PANI as 1, 3, 5, 7 wt % of V2O5 concentration. The above prepared samples were marked as tabulated in Table: 1 and Table:2.

[0095] The EC films of pristine V2O5, NiO incorporated V2O5 and NiO-PANI co-incorporated V2O5 were obtained by employing a conventional dip-coating method using a dip coater. Prior to dip-coating, the ITO coated glass substrates were cleaned successively with soap water, ethanol water and finally with acetone so as to ensure the complete cleaning of the material. The dipping process was conducted using a dipping speed of 20 cm / min a holding time of 30 sec and withdrawing speed of 10 cm / min. After coating was completed, the films were dried in a hot air oven for 30 mins at 80±5°C and after this the films were subjected to a heating schedule 350±5°C with a heating rateP_W0100793

[0096] of 5°C / min and a holding time of 3 h. The above prepared samples were marked as tabulated in Table: 1 and Table:2.

[0097] Cyclic Voltammetry (CV) measurement of the pristine and composition modified V2O5 films were done with Li-based electrolyte in a three-electrode system.

[0098] Optical performance of the typical EC film was measured using a three-electrode set-up. The detailed scheme is expressed in the following flow chart.

[0099] A typical electrochromic (EC) device or assembly has been fabricated with the optimized EC film having five layers sandwiched on either side that modifies the visual contrast between a colored and bleached state when a tiny voltage is applied, comprising the step of: - a. working electrode comprising ITO glass coated with NiO incorporated V2O5 or ITO glass coated with NiO and polyaniline co-incorporated V2O5 electrochromic films;

[0100] b. counter electrode comprising ITO glass coated with NiO as the ion storage layer;

[0101] c. electrolyte comprising a solid gel polymer electrolyte prepared from lithium perchlorate (LiC104) as the conducting ion material, propylene carbonate (PC) as a plasticizer, polymethyl methacrylate (PMMA) as a polymer matrix, and tetrahydrofuran (THF) as a solvent;

[0102] d. sandwiching the 1 wt % NiO - 5 wt% PANLV2O5 coated working electrode between the Li- based solid-gel electrolyte sheet / NiO / ITO counter electrode and leaving no space between the two electrodes;

[0103] e. sandwiching the 1 wt % NiO - 5 wt% PANLV2O5 coated working electrode between the Li- based solid-gel electrolyte sheet / NiO / ITO counter electrode and leaving no space between the two electrodes.

[0104] All the EC films thus prepared have been analyzed thoroughly with respect to their structural morphological, compositional, electrochemical and optical features respectively. Figure-2 demonstrates a schematic representation of the reaction path of the entire composition modification employing a three-step method). Figure-3a presents the structural representation of vanadium oxide layered structure and its modification after the composition modification. Figure-3b represents the modification of band structure of vanadium after synergistic composition engineering. Figure-4 corresponds to the bright field TEM image of pristine V2O5, which reveals agglomeration of elongated particles, while in figure-4b, NiO incorporation even to a smaller percentage result into the formation of rod like structures having a length of ~ 141 nm and breadth of 33 nm. The length of this rod like structure is further enhanced after the co-incorporation of 5 wt % PANI inside the metal oxide layersP_W0100793

[0105] (468 nm length and 80 nm breadth) (figure-4c). The HRTEM image of V20sin figure-4d demonstrates interplanar spacing of ~ 0.172 nm which also increases after the co-modification of the metal oxide composition (figure-4e). Figure 5 represents X-ray Photoelectron Spectroscopy plots of V2p core level spectrum (figure-5a) of 1 wt% NiO and 5 wt% PANI co-incorporated sample and the Ni2p (figure-5b), Ols (figure-5c), and Cis (figure-5d) spectra of 1 wt% NiO and 5 wt% PANI coincorporated sample. The core level XPS spectrums of V2p, Cis, Ols and Ni2p are further deconvoluted using Gaussian function by background fitting via Shirley method in order to obtain the exact oxidation states of the corresponding elements present in the samples. The deconvoluted V2p spectrum of 1 wt% NiO and 5 wt% PANI co-incorporated samples show peaks at -515.8 eV, and 518.1eV which resemble with V4+(2p3 / 2), and V5+(2p3 / 2) states respectively. Figure 6a represents the cyclic voltammogram of pristine V2O5, while figure 6b demonstrates a comparative study of the respective voltammograms of NiO incorporated V2O5 EC films with an increase in concentration from 0.5 to 2 wt% of V2O5, which shows that, NiO incorporation (from 0 to 1 wt%) results into an outstanding amplification in the integrated voltammogram area when compared with the pristine V2O5 sample, which implied more number of intercalated / de-intercalated Li+ions. However, increasing the NiO concentration, beyond this limit i.e. upto 2 wt%, significantly reduces the integrated area. Most possibly, the ~ 1 wt % NiO leads to a saturated concentration inside the V2O5 layers, and further increasing the concentration, an electrostatic repulsion intervened, which probably acts on to decline an adequate Li+intercalation thereby reducing the curve area, thus further on, no enhancement in the electrochemical redox reaction is observed. Therefore, based on this 1 wt% NiO is optimized for the additional characterization of NiO-PANI co-intercalated V20ssamples. Figure 6c demonstrates the cyclic voltammograms of the 1% NiO incorporated V20sfilms with varying PANI concentration. It is found that on increasing the PANI concentration from 1 to 5 wt% (1, 3, 5 wt%) there is a gradual increase in the voltammogram loop, indicating more ion accumulation on the EC films, which facilitates an elevation in the redox reaction. Nonetheless, the loop area decreases in VN1P7 sample. The higher concentration of PANI probably have resulted into greater entanglement of the polymer molecules, which facilitates a longer chain structure that perhaps hinders the Li+ion intercalation between the VOe layers. Figure 7a reveals the color-switching response of pristine V2O5 to be tc, 7.7±0.5sand tb, 15.3±0.5 s with an optical contrast of 13±2 %. Figure 7b, NiO incorporation results into increase in these values such as tc, 6.5±0.5s, tb, 6.8±0.5s and 53.4±2%. The enhancement in optical performance is ascribed to the higher conductivity and faster charge transfer. During repeated ion (de)insertion, the metal oxide usually undergoes fatigue and failures in its layer structure are accompanied by the loss of secondary bonding interaction. Accommodation of chain like conjugated polymer (PANI) hereafter, another type of interaction occurs between the d-orbitals of V-atoms and the 7r-7r* conjugation of PANI. This pursues to modulate the lean path between the layers in such a way that, e7ions gets a larger space thereby leading to much better scope of redox reaction. This effectP_W0100793

[0106] is extensively observed in the spectral performance of the optimized film figure 6c (coloration time, tc, 2.4±0.5s, bleaching time tb, 2.5±0.5s and optical contrast of75±0.2%). Additionally, PANI consisting of a longer chain-like structure and a larger electron density in its aromatic ring, nullifies this electrostatic repulsion, which ultimately adds to the outstanding stability in terms of optical (figure 8a) and electrochemical cyclic stability (figure 8b) of the optimized sample. A significantly visible color change is recognized which ultimately justifies the excellent multichromic behavior of the final EC composition. A multicolored representation from the three electrode system is shown in figure. 9a and a typical five-layered assembly structure is demonstrated in figure 9b.

[0107] Table- 1 Pristine and NiO incorporated V2O5 films and their electrochromic performance

[0108]

[0109] able-2NiO and PANI incorporated V2O5 films and their electrochromic performance

[0110]

[0111] NOVELTY AND NON-OBVIOUS INVENTIVE STEP(S):

[0112] The unique product is a multicolor tuning electrochromic device fabricated from the novel composition of NiO and PANI co-incorporated vanadium oxide EC films and the preparation method thereof disclosed by the invention is simple, convenient and has the excellent potential to enhance the optical contrast, switching response as well as the electrochemical cyclic stability. This invention describes an unprecedented method of a two way rectification of electrochromic vanadium oxide material in terms of attaining a synergistic improvement in the electronic band gap as well as enlargement in the interlayer spacing, which provoked the enhancement in opticalP_W0100793

[0113] modulation of the metal oxide, along with a faster switching kinetics and prolonged electrochemical lifetime. The optimized composition of (V : Ni : PANI ~ 1 : 0.01 : 0.05 wt % ratio) NiO-PANI co-incorporated V2O5 based EC film is able to change the optical modulation upto 75±5 %, with a faster switching time of tc, 2.4±0.5 sand tb , 2.5±0.5 s better electrochemical stability of 10000 cycles which are superior to those of pristine vanadium oxide (13±2 % optical contrast; switching time of tc, 7.7±0.5 s and tb , 15.5±0.5 s and 20000 cycles stability)

[0114] High optical contrast:- For an EC smart device, optical contrast i.e. the difference between the optical transmittance of the colored and the bleached state, is the most important property to be attained.In case of the transition metal oxides like V2O5, the electronic transition between the degenerated d-orbitals, determines the type and intensity of color shown by the material. Hence, intense color change owing to an efficient d-d* transition simply means modulation of the band gap. In the present invention, incorporation of metal cation (Nix+) has been an effective route for band gap rectification of V2O5, and thereby leads to advanced electrochemical properties. On the other side, vanadium oxide contains a layered structure of successive interconnected VOe units, having an interlayer distance of ~11.49 A, which is composed of embedded H2O molecules. This smaller interplanar spacing leads to the form of a narrow diffusion pathway, thus resulting in a trivial number of electrons / coun ter-cation that interact insignificantly with V2O5 and are responsible for weak color generation. The conjugated polymers bearing a larger chain -like structure, require a wide space, hence when incorporated in between the inter-layer spaces of V2O5 expands the spacing, thereby increasing the ion diffusion pathway, facilitating better interaction of ions / electrons, and resulting in more intense coloration.

[0115] Fast switching kinetics: -In addition to the optical contrast, the time required for switching between the colored and the bleached state is an important parameter to be considered for an electrochromic device. The enhanced layered space of V2O5 structure, after the incorporation poly aniline, facilitated a mobile and smoother pathway for electrons and charge to move through which resulted into a faster color switching response (tc, 2.4±0.5 s and tb , 2.5±0.5 s) of the composition remodelled material.

[0116] Facile process: - The synthesis process for the fabrication of the novel multicolored electrochromic composition, described in this invention consisted of unique combinations of components involving simple precursors obtained by following simple steps. The precursor materials used over the invention, are all operable at ambient temperature and pressure conditions.

[0117] Cost effectiveness: -The multicolored electrochromic material mentioned in this invention provides a stable EC composition in terms of its electrochemical redox stability by attaining aP_W0100793

[0118] cycle life of 10000 cycles with maximum retention of optical contrast. Hence, this proposed EC system will reduce the cost by simply eliminating the urge of replacement of smart display after short period of time. Also, the voltage requirement here is lower as compared to the conventional emissive displays provided by the LEDs.

[0119] Stability:- The capacity of a metal oxide structure to revert to its initial state following numerous cycles of charge intercalation and de-intercalation is known as stability in electrochromic materials. The long chain polymer structure of PANI, incorporated into the V2O5 layered structure, created a longer charge diffusion channel and more room for the structure to alleviate the strain caused by an extended electrochemical redox cycle.

[0120] EXAMPLE

[0121] The following examples, which include preferred embodiments, will serve to illustrate the practice of this invention, it being understood that the particulars shown are by way of example and for purpose of illustrative discussion of preferred embodiments of the invention and therefore should not be construed to limit the scope of the present invention.

[0122] EXAMPLE-1

[0123] 0.6 g of hydrated vanadium oxide (V2O5.XH2O), 0.02 g of N,N,N- cetyltrimethylammonium bromide (CTAB), 0.05 ml of polyvinyl pyrrolidone (PVP) were taken into a 100 ml beaker and 30mL of ethanol (C2H5OH) was added to it. The mixture was ultrasonicated for 45 mins in order to ensure proper dispersion of the precursor salts and then it was stirred for 24 h for uniform mixing and forming a homogeneous transparent solution. After 24 h, the solution was kept undisturbed for 72 h so as to give sufficient time for ageing of the prepared solution. After 72 h, the sol formed was used for dip-coating on ITO coated glass substrate. For coating, the ITO coated glass substrates having dimension 3 cm X 4 cm and a resistance of 10 Q / cm2, were cleaned successively using soap water, D.I water and then with ethanol, after washing, the substrates were dried at 70±5 °C for 2 h in a hot air oven. The dipping process was conducted using a dipping speed of 20 cm / min, a holding time of 30 sec and a withdrawing speed of 10 cm / min. After coating was completed, the films were dried in a hot air oven for 30 mins at 80±5 °C and after this the films were subjected to a heating schedule at 350±5 °C with a heating rate of 5°C / min and a holding time of 3 h.

[0124] Electrochemical characterization

[0125] The redox performance of the prepared EC film composition was evaluated by Cyclic Voltammetry measurement in Electrochemical Workstation (Pine Instrument, USA, Wave Driver 100) using a three-electrode system. All the experiments were performed using a 3.24 cm2EC filmP_W0100793

[0126] area working electrode, saturated calomel electrode as the reference electrode and platinum as the counter electrode. The redox reaction was monitored by changing the potential from -1 V to +1 V. The acquired data was then analyzed by comparing the integrated hysteresis curve area of the pristine V2O5 sample.

[0127] Optical characterization

[0128] The optical transmittance spectra of the samples were measured simultaneously during the cyclic voltammetry experiment using an in-situ UV-Vis Spectrophotometer from Avantes coupled with the Pine Wave Driver. The transmittance changes occurred during coloration and bleaching cycles with respect to time revealed the change in optical transmittance i.e. the optical contrast of the pristine V2O5 sample.

[0129] EXAMPLE-2

[0130] 0.6 g of hydrated vanadium oxide (V2O5.XH2O), 0.003 g of NiO, 0.02 g of N,N,N-cetyltrimethylammonium bromide (CTAB), 0.05ml of polyvinyl pyrrolidone (PVP) were taken into a 100 ml beaker and 30mL of ethanol (C2H2OH) was added to it. The mixture was ultrasonicated for 45 mins in order to ensure proper dispersion of the precursor salts and then it was stirred for 24 h for uniform mixing and forming a homogeneous transparent solution. After 24 h, the solution was kept undisturbed for 72 h so as to give sufficient time for ageing of the prepared solution. After 72 h, the sol formed was used for dip-coating on ITO coated glass substrate. For coating, the ITO coated glass substrates having dimension 3 cm X 4 cm and a resistance of 10 Q / cm2, were cleaned successively using soap water, D.I water and then with ethanol, after washing the substrates were dried at 70±5 °C for 2 h in a hot air oven. The dipping process was conducted using a dipping speed of 20 cm / min, a holding time of 30 sec and a withdrawing speed of 10 cm / min. After coating was completed, the films were dried in a hot air oven for 30 mins at 80±5 °C and after this the films were subjected to a heating schedule 350±5 °C with a heating rate of 5°C / min and a holding time of 3 h.

[0131] Electrochemical characterization

[0132] The redox performance of the prepared EC film composition was evaluated by Cyclic Voltammetry measurement in Electrochemical Workstation (Pine Instrument, USA, Wave Driver 100) using a three-electrode system. All the experiments were performed using a 3.24 cm2EC film area working electrode, saturated calomel electrode as the reference electrode and platinum as the counter electrode. The redox reaction was monitored by changing the potential from -1 V to +1 V. The acquired data was then analyzed by comparing the integrated hysteresis curve area of the pristine V2O5 and the 0.5 wt% NiO incorporated V2O5 sample.P_W0100793

[0133] Optical characterization

[0134] The optical transmittance spectra of the samples were measured simultaneously during the cyclic voltammetry experiment using an in-situ UV-Vis Spectrophotometer from Av antes coupled with the Pine Wave Driver. The transmittance changes occurred during coloration and bleaching cycles with respect to time revealed the change in optical transmittance i.e. the optical contrast of the 0.5 wt% NiO incorporated V2O5 samples.

[0135] EXAMPLE-3

[0136] 0.6 g of hydrated vanadium oxide (V2O5.XH2O), 0.006 g of NiO, 0.02 g of N,N,N-cetyltrimethylammonium bromide (CTAB), 0.05 ml of polyvinyl pyrrolidone (PVP) were taken into a 100 ml beaker and 30mL of ethanol (C2H5OH) was added to it. The mixture was ultrasonicated for 45 mins in order to ensure proper dispersion of the precursor salts and then it was stirred for 24 h for uniform mixing and forming a homogeneous transparent solution. After 24 h, the solution was kept undisturbed for 72 h so as to give sufficient time for ageing of the prepared solution. After 72 h, the sol formed was used for dip-coating on ITO coated glass substrate. For coating, the ITO coated glass substrates having dimension 3 cm X 4 cm and a resistance of 10 Q / cm2, were cleaned successively using soap water, D.I water and then with ethanol, after washing the substrates were dried at 70±5 °C for 2 h in a hot air oven. The dipping process was conducted using a dipping speed of 20 cm / min, a holding time of 30 sec and a withdrawing speed of 10 cm / min. After coating was completed, the films were dried in a hot air oven for 30 mins at 80±5°C and after this the films were subjected to a heating schedule 350±5 °C with a heating rate of 5°C / min and a holding time of 3 h.

[0137] Electrochemical characterization

[0138] The redox performance of the invented EC film composition was evaluated by Cyclic Voltammetry measurement in Electrochemical Workstation (Pine Instrument, USA, Wave Driver 100) using a three-electrode system. All the experiments were performed using a 3.24 cm2EC film area working electrode, saturated calomel electrode as the reference electrode and platinum as the counter electrode. The redox reaction was monitored by changing the potential from -1 V to +1 V. The acquired data was then analyzed by comparing the integrated hysteresis curve area of the pristine V2O5 and the 1 wt% NiO incorporated V2O5 sample.

[0139] Optical characterization

[0140] The optical transmittance spectra of the samples were measured simultaneously during the cyclic voltammetry experiment using an in-situ UV-Vis Spectrophotometer from Av antes coupled withP_W0100793

[0141] the Pine Wave Driver. The transmittance changes occurred during coloration and bleaching cycles with respect to time revealed the change in optical transmittance i.e. the optical contrast of the 1 wt% NiO incorporated V2O5 samples.

[0142] EXAMPLE-4

[0143] 0.6 g of hydrated vanadium oxide (V2O5.XH2O), 0.012 g of NiO, 0.02 g of N,N,N-cetyltrimethylammonium bromide (CTAB), 0.05 ml of polyvinyl pyrrolidone (PVP) were taken into a 100 ml beaker and 30mL of ethanol (C2H5OH) was added to it. The mixture was ultrasonicated for 45 mins in order to ensure proper dispersion of the precursor salts and then it was stirred for 24 h for uniform mixing and forming a homogeneous transparent solution. After 24 h, the solution was kept undisturbed for 72 h so as to give sufficient time for ageing of the prepared solution. After 72 h, the sol formed was used for dip-coating on ITO coated glass substrate. For coating, the ITO coated glass substrates having dimension 3 cm X 4 cm and a resistance of 10 Q / cm2, were cleaned successively using soap water, D.I water and then with ethanol, after washing the substrates were dried at 70±5 °C for 2 h in a hot air oven. The dipping process was conducted using a dipping speed of 20 cm / min, a holding time of 30 sec and a withdrawing speed of 10 cm / min. After coating was completed, the films were dried in a hot air oven for 30 mins at 80±5 °C and after this the films were subjected to a heating schedule 350±5 °C with a heating rate of 5°C / min and a holding time of 3 h.

[0144] Electrochemical characterization

[0145] The redox performance of the invented EC film composition was evaluated by Cyclic Voltammetry measurement in Electrochemical Workstation (Pine Instrument, USA, Wave Driver 100) using a three-electrode system. All the experiments were performed using a 3.24 cm2EC film area working electrode, saturated calomel electrode as the reference electrode and platinum as the counter electrode. The redox reaction was monitored by changing the potential from -1 V to +1 V. The acquired data was then analyzed by comparing the integrated hysteresis curve area of the pristine V2O5 and the 2 wt% NiO incorporated V2O5 sample.

[0146] Optical characterization

[0147] The optical transmittance spectra of the samples were measured simultaneously during the cyclic voltammetry experiment using an in-situ UV-Vis Spectrophotometer from Av antes coupled with the Pine Wave Driver. The transmittance changes occurred during coloration and bleaching cycles with respect to time revealed the change in optical transmittance i.e. the optical contrast of the 2 wt% NiO incorporated V2O5 samples.P_W0100793

[0148] EXAMPLE-5

[0149] 0.6 g of hydrated vanadium oxide (V2O5.XH2O), 0.006 g of NiO, 0.006g of polyaniline (PANI) powder, 0.02 g of N,N,N-cetyltrimethylammonium bromide (CTAB), 0.05 ml of polyvinyl pyrrolidone (PVP) were taken into a 100 ml beaker and 30mL of Ethanol (C2H5OH) was added to it. The mixture was ultrasonicated for 45 mins in order to ensure proper dispersion of the precursor salts and then it was stirred for 24 h for uniform mixing and forming a homogeneous transparent solution. After 24 h, the solution was kept undisturbed for 72 h so as to give sufficient time for ageing of the prepared solution. After 72 h, the sol formed was used for dip-coating on ITO coated glass substrate. For coating, the ITO coated glass substrates having dimension 3 cm X 4 cm and a resistance of 10 Q / cm2, were cleaned successively using soap water, D.I water and then with ethanol, after washing the substrates were dried at 70±5°C for 2 h in a hot air oven. The dipping process was conducted using a dipping speed of 20 cm / min, a holding time of 30 sec and a withdrawing speed of 10 cm / min. After coating was completed, the films were dried in a hot air oven for 30 mins at 80±5 °C and after this the films were subjected to a heating schedule 350±5 °C with a heating rate of 5°C / min and a holding time of 3 h.

[0150] Electrochemical characterization

[0151] The redox performance of the invented EC film composition was evaluated by Cyclic Voltammetry measurement in Electrochemical Workstation (Pine Instrument, USA, Wave Driver 100) using a three-electrode system. All the experiments were performed using a 3.24 cm2EC film area working electrode, saturated calomel electrode as the reference electrode and platinum as the counter electrode. The redox reaction was monitored by changing the potential from -1.5 V to +1.5 V. The acquired data was then analyzed by comparing the integrated hysteresis curve area of the pristine V2O5 and the lwt% NiO-1 wt% PANI co-incorporated V2O5 sample.

[0152] Optical characterization

[0153] The optical transmittance spectra of the samples were measured simultaneously during the cyclic voltammetry experiment using an in-situUV-Vis Spectrophotometer from Avantes coupled with the Pine Wave Driver. The transmittance changes occurred during coloration and bleaching cycles with respect to time revealed the change in optical transmittance i.e. the optical contrast of the lwt% NiO-1 wt% PANI co-incorporated V2O5 sample.

[0154] EXAMPLE-6

[0155] 0.6 g of hydrated Vanadium oxide (V2O5.XH2O), 0.006 g of NiO, 0.018g of polyaniline (PANI) powder, 0.02 g of N,N,N- cetyltrimethylammonium bromide (CTAB), 0.05 ml of polyvinyl pyrrolidone (PVP) were taken into a 100 ml beaker and 30mL of ethanol (C2H5OH) was added toP_W0100793

[0156] it. The mixture was ultrasonicated for 45 mins in order to ensure proper dispersion of the precursor salts and then it was stirred for 24 h for uniform mixing and forming a homogeneous transparent solution. After 24 h, the solution was kept undisturbed for 72 h so as to give sufficient time for ageing of the prepared solution. After 72 h, the sol formed was used for dip-coating on ITO coated glass substrate. For coating, the ITO coated glass substrates having dimension 3 cm X 4 cm and a resistance of 10 Q / cm2, were cleaned successively using soap water, D.I water and then with ethanol, after washing the substrates were dried at 70±5°C for 2 h in a hot air oven. The dipping process was conducted using a dipping speed of 20 cm / min, a holding time of 30 sec and a withdrawing speed of 10 cm / min. After coating was completed, the films were dried in a hot air oven for 30 mins at 80±5°C and after this the films were subjected to a heating schedule 350±5°C with a heating rate of 5°C / min and a holding time of 3 h.

[0157] Electrochemical characterization

[0158] The redox performance of the invented EC film composition was evaluated by Cyclic Voltammetry measurement in Electrochemical Workstation (Pine Instrument, USA, Wave Driver 100) using a three-electrode system. All the experiments were performed using a 3.24 cm2EC film area working electrode, saturated calomel electrode as the reference electrode and platinum as the counter electrode. The redox reaction was monitored by changing the potential from -1.5 V to +1.5 V. The acquired data was then analyzed by comparing the integrated hysteresis curve area of the pristine V2O5 and lwt% NiO-3 wt% PANI co-incorporated V2O5 sample.

[0159] Optical characterization

[0160] The optical transmittance spectra of the samples were measured simultaneously during the cyclic voltammetry experiment using an in-situ UV-Vis Spectrophotometer from Shimadzu coupled with the Pine Wave Driver. The transmittance changes occurred during coloration and bleaching cycles with respect to time revealed the change in optical transmittance i.e. the optical contrast of lwt% NiO-3 wt% PANI co-incorporated V2O5 sample.

[0161] EXAMPLE-7

[0162] 0.6 g of hydrated Vanadium oxide (V2O5.XH2O), 0.003 g of NiO, 0.03g of polyaniline (PANI) powder, 0.02 g of N,N,N- cetyltrimethylammonium bromide (CTAB), 0.05 ml of polyvinyl pyrrolidone (PVP) were taken into a 100 ml beaker and 30mL of ethanol (C2H5OH) was added to it. The mixture was ultrasonicated for 45 mins in order to ensure proper dispersion of the precursor salts and then it was stirred for 24 h for uniform mixing and forming a homogeneous transparent solution. After 24 h, the solution was kept undisturbed for 72 h so as to give sufficient time for ageing of the prepared solution. After 72 h, the sol formed was used for dip-coating on ITO coatedP_W0100793

[0163] glass substrate. For coating, the ITO coated glass substrates having dimension 3 cm X 4 cm and a resistance of 10 Q / cm2, were cleaned successively using soap water, D.I water and then with ethanol, after washing the substrates were dried at 70±5°C for 2 h in a hot air oven. The dipping process was conducted using a dipping speed of 20 cm / min, a holding time of 30 sec and a withdrawing speed of 10 cm / min. After coating was completed, the films were dried in a hot air oven for 30 mins at 80±5°C and after this the films were subjected to a heating schedule 350±5°C with a heating rate of 5°C / min and a holding time of 3 h.

[0164] Electrochemical characterization

[0165] The redox performance of the invented EC film composition was evaluated by Cyclic Voltammetry measurement in Electrochemical Workstation (Pine Instrument, USA, Wave Driver 100) using a three-electrode system. All the experiments were performed using a 3.24 cm2EC film area working electrode, saturated calomel electrode as the reference electrode and platinum as the counter electrode. The redox reaction was monitored by changing the potential from -1.5 V to +1.5 V. The acquired data was then analyzed by comparing the integrated hysteresis curve area of the pristine V2O5 and lwt% NiO-5 wt% PANI co-incorporated V2O5 sample.

[0166] Optical characterization

[0167] The optical transmittance spectra of the samples were measured simultaneously during the cyclic voltammetry experiment using an in-situ UV-Vis Spectrophotometer from Shimadzu coupled with the Pine Wave Driver. The transmittance changes occurred during coloration and bleaching cycles with respect to time revealed the change in optical transmittance i.e. the optical contrast of lwt% NiO-5 wt% PANI co-incorporated V2O5 sample.

[0168] EXAMPLE-8

[0169] 0.6 g of hydrated Vanadium oxide (V2O5.XH2O), 0.003 g of NiO, 0.042g of polyaniline (PANI) powder, 0.02 g of N,N,N- cetyltrimethylammonium bromide (CTAB), 0.05 ml of polyvinyl pyrrolidone (PVP) were taken into a 100 ml beaker and 30mL of ethanol (C2H5OH) was added to it. The mixture was ultrasonicated for 45 mins in order to ensure proper dispersion of the precursor salts and then it was stirred for 24 h for uniform mixing and forming a homogeneous transparent solution. After 24 h, the solution was kept undisturbed for 72 h so as to give sufficient time for ageing of the prepared solution. After 72 h, the sol formed was used for dip-coating on ITO coated glass substrate. For coating, the ITO coated glass substrates having dimension 3 cm X 4 cm and a resistance of 10 Q / cm2, were cleaned successively using soap water, D.I water and then with ethanol, after washing the substrates were dried at 70±5°C for 2 h in a hot air oven. The dipping process was conducted using a dipping speed of 20 cm / min, a holding time of 30 sec and aP_W0100793

[0170] withdrawing speed of 10 cm / min. After coating was completed, the films were dried in a hot air oven for 30 mins at 80±5°C and after this the films were subjected to a heating schedule 350±5°C with a heating rate of 5°C / min and a holding time of 3 h.

[0171] Electrochemical characterization

[0172] The redox performance of the invented EC film composition was evaluated by Cyclic Voltammetry measurement in Electrochemical Workstation (Pine Instrument, USA, Wave Driver 100) using a three-electrode system. All the experiments were performed using a 3.24 cm2EC film area working electrode, saturated calomel electrode as the reference electrode and platinum as the counter electrode. The redox reaction was monitored by changing the potential from -1.5 V to +1.5 V. The acquired data was then analyzed by comparing the integrated hysteresis curve area of the pristine V2O5 and lwt% NiO-7 wt% PANI co-incorporated V2O5 sample.

[0173] Optical characterization

[0174] The optical transmittance spectra of the samples were measured simultaneously during the cyclic voltammetry experiment using an in-situ UV-Vis Spectrophotometer from Shimadzu coupled with the Pine Wave Driver. The transmittance changes occurred during coloration and bleaching cycles with respect to time revealed the change in optical transmittance i.e. the optical contrast of the lwt% NiO-7 wt% PANI co-incorporated V2O5 sample.

[0175] ADVANTAGES OF THE INVENTION

[0176] The main advantages of the present invention are:

[0177] • V2O5 based multicolored electrochromic films with polyaniline and NiO having High optical contrast.

[0178] • V2O5 based multicolored electrochromic films with polyaniline and NiO showing Fast switching kinetics between the colored and the bleached state.

[0179] • The synthesis process for the fabrication of the novel multicolored electrochromic composition, described in this invention consisted of unique combinations of components involving simple precursors obtained by following simple steps, conditions.

[0180] • The multicolored electrochromic material in the present invention provides a stable EC composition in terms of its electrochemical redox stability by attaining a cycle life of 10000 cycles with maximum retention of optical contrast.

[0181] • V2O5 based multicolored electrochromic films will reduce the cost by simply eliminating the urge of replacement of smart display after short period of time.P_W0100793

[0182] • V2O5 based multicolored electrochromic films having low voltage requirement as compared to the conventional emissive displays provided by the LEDs.

[0183] • V2O5 based multicolored electrochromic films with polyaniline and NiO having longer charge diffusion channel and more room for the structure to alleviate the strain caused by an extended electrochemical redox cycle.

Claims

1. P_W0100793We claim: - 1. A fabrication of two-electrode NiO and polyaniline (PANI) co-incorporated V2O5 electrochromic films based multicolored electrochromic film device comprising: - a. a working electrode consisting Indium tin oxide (ITO glass) coated with NiO and polyaniline co-incorporated V2O5 electrochromic films;b. a counter electrode comprising ITO glass coated with NiO as the ion storage layer; c. a Li- based solid gel polymer electrolyte;d. sandwiching the 1 wt % NiO - 5 wt% PANLV2O5 coated working electrode between the Li-based solid-gel electrolyte sheet / NiO / ITO counter electrode and leaving no space between the two electrodes;2. The ITO glass coated with NiO and polyaniline co-incorporated V2O5 electrochromic films as working electrode as claimed in claim 1 , wherein the process for preparation of polyaniline coincorporated V2O5 electrochromic films comprising the steps of:a. mixing NiO, polyaniline, and hydrated V2O5 powders in a ratio of 0.01:0.01:1, followed by grinding the mixture for 30 minutes in an agate mortar;b. transferring the mixture into a glass beaker, adding 4 wt. % hexadecyltrimethylammonium bromide (CTAB), 10 wt. % aqueous polyvinyl pyrrolidone (PVP), and ethanol as a solvent, and ultrasonically treating the mixture for 45 minutes;c. stirring the resultant solution for 24 hours and aging it for an additional 72 hours to obtain NiO and polyaniline co-incorporated V2O5 sols;d. cleaning ITO-coated glass substrates 9(10 cm X 10 cm) with soap water, deionized water, and ethanol to obtain cleaned substrates;e. dip-coating the cleaned substrates as obtained in step (d) in the NiO and polyaniline co-incorporated V2O5 sols as obtained in step (c) at a dipping speed of 20 cm / min, holding the substrates in the solution for 1 minute, and withdrawing the substrates at a speed of 10 cm / min;f. drying the coated films at 60°C for 2 hours;P_W0100793g. heating the dried films at 350°C with a heating rate of 3°C / min, holding at 350°C for 3 hours, and cooling at a rate of 3°C / min to obtain ITO glass coated with NiO and polyaniline co-incorporated V2O5 electrochromic films.

3. The Li-based solid gel polymer electrolyte as claimed in claim 1, wherein the process for preparation comprising the steps of:mixing of 10-20 wt. % Lithium perchlorate (LiC104) as conducting ion material, 40-50 wt. % of Propylene Carbonate (PC) as plasticizer and 20-30 wt % Polymethyl methacrylate (PMMA) as polymer matrix in Tetrahydrofuran (THF) as solvent.

4. The two-electrode NiO and polyaniline co-incorporated V2O5 electrochromic films based multicolored electrochromic film device as claimed in claim 1, wherein the color of the electrochromic film device changed from yellow to green at 0.2 V, then to brown at 0.4 V and to orange at 0.8 V.

5. The two-electrode NiO and polyaniline co-incorporated V2O5 electrochromic films based multicolored electrochromic film device as claimed in claim 1, wherein electrochromic film device provides maximum optical contrast of 75±2% between colored and bleached state by tuning the external voltage from - 1.5 V to + 1.5 V and vice versa.

6. The two-electrode NiO and polyaniline co-incorporated V2O5 electrochromic films based multicolored electrochromic film device as claimed in claim 1 , wherein an optical contrast of 75 ±2% obtained in the as fabricated optimized electrochromic composition with NiO and polyaniline (PANI) co-incorporation into V2O5 structure which is far better than optical contrast of the conventional vanadium oxide electrochromic film (13 ±5 %).

7. The two-electrode NiO and polyaniline co-incorporated V2O5 electrochromic films based multicolored electrochromic film device as claimed in claim 1, wherein a color switching kinetics having coloration time of (tc) 2.4±0.5s and bleaching time (tb) of 2.5±0.5s.

8. The two-electrode NiO and polyaniline co-incorporated V2O5 electrochromic films based multicolored electrochromic film device as claimed in claim 1 , wherein a robust multicolored EC provides electrochemical cyclic stability of 10000 cycles.

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