FTO Glass Research Articles

Perovskite solar cells based on CH3NH3SnI3 Structure

In recent years, organic-inorganic perovskite solar cells have attracted considerable interest in the photovoltaic research community because of its ease of processing, low production costs, super light-harvesting characteristics, and relatively high performance, making it more desirable than other current solar cell materials. Lead-based perovskites (CH3NH3PbX3, X=Cl, I, Br) solar cells have recently achieved high efficiency of ∼19.3 percent, well exceeding most thin-film and organic solar cells’ efficiencies. The presence of lead, toxic material in these solar cells, therefore poses serious challenges to our health and the environment. ‘Tin’ is nontoxic and stands as a replacement to ‘lead’ for commercial purposes. in halide based Perovskites possess a potential for higher quantum efficiency because of their enhanced light absorption capability due to the wide-ranging absorption spectrum in the visible region with a comparatively lower band gap of 1.3 eV than lead-based Perovskites. In this work, we have modeled a tin-based perovskite simulation model with FTO Glass / ZnO / CH3NH3SnI3 / Cu2O / Pt. novel architecture and analyzed using the SCAPS-1D, which is well suited for studying photovoltaic architecture. Use this software method and we analyzed the thickness, fault density, and operating temperature of the model by simulating under various conditions. With the optimize the thickness to be (0.03 μm) corresponding best efficiency among another thickness of perovskites, and other layers, the defect density of absorber layer (1017 cm-3 ) the encouraging result of maximum power conversion efficiency(PCE) reached to 9.27%, the short-circuit current density(Jsc) is 46.569 mA/cm2, and fill factor(FF) is 31.17% and open-circuit voltage(Voc) is 0.637 V is calculated.

Analysis of optical linearity and nonlinearity of Fe3+- doped PMMA/FTO polymeric films: New trend for optoelectronic polymeric devices

Iron-doped polymethylmethacrylate (Fe3+/PMMA) films were deposited on FTO glass substrates. X-ray diffractometer (XRD), Fourier-transform infrared spectroscopy (FT-IR) were applied to examine the structure of Fe3+/PMMA/FTO films with varying doping percentages of iron-ions. The obtained XRD diffraction results proved the uniform and semi-crystalline in nature of the tested samples. The vibrational modes of both metal-ions and host PMMA polymers were respectively observed at 450 and 980 cm−1. The direct optical energy bandgaps for the proposed undoped and Fe3+-doped PMMA thin films were valued to be approximately 4.11, 4.1004, 4.094, 4.087, 4.07, 3.801, and 3.35 eV. The indirect energy bandgaps were 3.605, 3.58, 3.55, 3.504, 2.85, and 2.37 eV with increasing the Fe3+-contents, respectively. Moreover, the optical limiting of Fe3+/PMMA/FTO films was studied through red He-Ne and green diode lasers operating at 632.8 and 532 nm, correspondingly. Finally, Fe3+-doped PMMA/FTO composites are considered an excellent candidate for various optoelectronic devices.

TiO2 paste for DSSC photoanode: preparation and optimization of application method

We propose a simple method of TiO2 paste preparation from titania powder (Degussa) and organic binders (terpineol, ethyl cellulose) for making a continuous photoactive layer of a dye-sensitized solar cell (DSSC). The prepared paste was characterized by using thermogravimetric and X-ray diffraction methods for comparison with commercial paste (Solaronix). The TiO2 layer parameters for applying and annealing were optimized by varying the layer thickness and using different masks. The surface morphology of annealed layers was controlled by optical microscopy. Before TiO2 paste applying and after annealing, the conductive glass (fluorine-tin oxide – FTO) was treated by TiCl4 hydrochloric acid solution. The structure of DSSCs were composed FTO-glass / TiO2 layer sensitized Ruthenium complex (N719 dye)/ iodide-based electrolyte / Pt counter electrode/ FTO glass. The DSSC photovoltaic characteristics were measured under AM 1.5G irradiation and demonstrated to be close to those of photoanodes based on the prepared and commercial pastes.

Electrothermally control of dynamic infrared switching of VO2 thin film on FTO glass

Toward controlling the metal-insulator transition (MIT) of VO2 in a facile method for dynamically tuning infrared transmission, we report one-step VO2 thin film deposition on FTO/glass substrate without post annealing using the reactive sputtering deposition technique. The MIT of VO2 thin films and their infrared modulation characteristics were investigated. Using the FTO underlayer as a resistive heating element, the MIT of large area VO2 thin films can be easily achieved. Dynamic tuning the infrared transmission or abrupt infrared switching through voltage control was demonstrated. Our results suggest that voltage driven VO2/FTO/glass through electrothermally control VO2 phase change can be a promising candidate for smart window and infrared switching applications.

The effect of CuS counter electrode microtopography on the properties of quantum dot sensitized solar cells

The counter electrode (CE) is an essential working part in quantum dots sensitized solar cells (QDSCs), which performs the function of extracting electrons form external circuit and catalyzing the reduction of electrolyte. Usually, CuS based composite acts as CEs in QDSCs to realize the dual functions. In this work, the microtopography of CuS film on FTO glass was modified through changing preparation route and conditions to investigate the possibility of mono component CuS film as CEs in liquid junction QDSCs. Two kinds of CuS CEs were prepared on FTO conductive glass substrate through successive ionic layer adsorption and reaction (SILAR) and modified hydrothermal method, respectively. Based on the results of XRD, SEM and EDX characterization, ECS and J-V curves were analyzed to investigate the effect of CEs’ particle size, microstructure and film morphology on the photovoltaic properties of QDSC samples. The results showed that CuS CEs prepared through appropriate SILAR cycle times exhibited higher catalyzing ability due to smaller diameter of CuS particles and uniform distribution of CuS particles in film, compared with those with modified hydrothermal method. CuS CEs with 10 deposition cycles showed the best catalyzing ability of the lowest charge transfer resistance (3.00 Ω) on CE/electrolyte interface and the power conversion efficiency (PCE) of QDSC consisting of this CuS CE reached 3.83%.

Analysis of Ferroelectric Thin Film BaZr0.6Ti0.4O3 with Annealing Temperature Increase Variations Using x-ray Diffraction

Ferroelectric is a dielectric material which has spontaneous polarization and has the ability to change its internal polarization using a suitable electric field. The aim of this research is to decrease the FWHM value and increase the crystal size so that the dielectric constant increases for capacitor applications. Thin film ferroelectric material of Barium Zirconium Titanate (BZT) with the composition BaZr0.6Ti0.4O3 was prepared using the sol-gel method. The substrate used was FTO glass which has been treated etching and coated with BZT and in annealing at 800° C with annealing temperature increase of 5°C and 10°C. Samples were characterized using XRD with an angle interval of 2θ between 20° to 60°. The results of XRD characterization show that there were peaks indicating that there was a crystal structure. The resulting crystal structure was in a plane 100 at an angle of 2θ = 22.55°, a plane 110 at an angle of 2θ = 32.00°, a plane 111 at an angle of 2θ = 38.54°, and a plane 200 at an angle of 2θ = 47.64°. The resulting structure in this study was tetragonal where a = b = 3.955 and c = 4.266. The rate at which temperature rose had an effect on the peak of X-Ray diffraction. The FWHM value for 5°C was less than 10°C. This implies a greater density when annealing at 5°C. The crystal size values obtained with an increase in temperature of 5°C and 10°C in the 100 plane were 3.22 and 2.954, respectively. The crystal size was inversely proportional to the FWHM value where the small speed of the annealing temperature increase caused the crystal size to enlarge.

In situ grown NiIn2S4 nanosheets as counter electrode for bifacial quasi-solid-state dye-sensitized solar cells

The development of counter electrode (CE) catalytic materials with cost-effective and excellent catalytic activity, transparency, good stability, and simple fabrication process is urgently needed for bifacial quasi-solid-state dye-sensitized solar cells (BQDSSCs). Herein, NiS1.97 nanoparticles, In2.77S4 and NiIn2S4 nanosheet structures were successfully constructed by a one-step in situ solvothermal method on an FTO glass substrate to act as counter electrodes (CEs). The electrochemical results revealed that the NiIn2S4 interconnected nanosheet CE exhibited enhanced electrocatalytic activity for the reduction of I3−, which can be attributed to the unique structure with a large contact area for the electrolyte and FTO substrate, enhancing electron transfer and providing effective catalytic sites. The BQDSSCs based on the NiIn2S4 CE showed the superior front and rear illumination Jsc values of 15.27 and 9.13 mA cm−2, and power conversion efficiencies (PCEs) of 8.00% and 4.59%, respectively, which were higher than those of binary NiS1.97 and In2.77S4, and comparable to the Pt CE with front and rear efficiencies of 7.42% and 3.93%, respectively. Furthermore, the NiIn2S4 CE film displayed a high multiple on–off switching response and good stability, suggesting that ternary sulfides could be promising alternatives for CE materials in BQDSSCs. The NiIn2S4 nanosheet BQDSSC yields front and rear PCEs of 8.00 and 4.59%, higher than those of NiS1.97, In2.77S4, and Pt CEs, respectively.

TiO2/GO nanocomposites: synthesis, characterization, and DSSC application

In this investigation, titanium dioxide and TiO2/graphene oxide nanocomposites were synthesized and coated on FTO glass using the doctor blade method to act as a photoanode in the fabricated dye-sensitized solar cells. X-ray diffraction pattern analysis, Raman spectroscopy, and FTIR confirmed the presence of GO in TiO2/GO nanocomposites. XRD peaks of the TiO2 sample were indexed to the tetragonal rutile structure; however, some weak peaks were also assigned to the anatase phase. In addition, the amount of GO in the composite caused an increase in current density from 10.18 mAcm−2 in the fabricated cell using pure TiO2 to 10.79 mAcm−2 in the cell fabricated using 0.001 wt% GO in TiO2/GO nanocomposite. The obtained results give insights into the role of GO in the enhancement of the DSSC device’s performance and present a simple method for the synthesis of novel photoanodes.

THE EFFECT OF ZnO/NiO NANOCOMPOSITE ON THE PROPERTIES OF A PHOTOELECTRODE OF A DYE SENSITIZED SOLAR CELL

The aim of the article was to investigate the structure and optical and properties of the ZnO/NiO nanoparticle layer with a different percentage of individual components produced by the sol-gel method. The influence of the developed layers on the properties of dye sensitized solar cells was also determined. Phase identification of the ZnO and NiO samples was confirmed by X-ray diffraction and TEM analysis. From the synthesized nanoparticles, a ZnO/NiO layer was prepared by screen printing method. Studies of the surface morphology of this layer from as prepared nanoparticles, deposited on an FTO glass substrate, was performed by using scanning electron microscopy. Current-voltage characteristics of dye-sensitized solar cells with ZnO/NiO layer and platinum counter electrodes were performed using PV Test Solutions Tadeusz Żdanowicz Solar Cell I-V Tracer System with solar simulator and Keithley 2400 source meter. The best results were obtained for a solar cell containing a ZnO/NiO nanocomposite with 70/30 ratio and its efficiency was 4.46%.

Effect of Annealing Temperature on Efficiency of Perovskite Solar Cell

In this work, a simple method for producing Perovskite solar cells [PSCs] by recycling automobile batteries is used. Trying to get rid of some structures or materials which are harm to the environment (i.e. recycled car batteries) by using lead [Pb] sheets from those battery. Also, by reusing car batteries we will avoid the disposal of toxic battery elements and provide an alternative technique, readily-available Pb source for fabricating PSCs. Perovskite solar cells [PSCs] were prepared by two-step spin coating solution method grown on the FTO glass substrate. The organo-halide PSCs consists of four layers over FTO glass substrate. Lead iodide (PbI2) and methyl-ammonium iodide (CH3NH3I) used to form the structure of the precursor (CH3NH3PbI3) by the above-mentioned coating method. The photovoltaic performance of PSCs was investigated, together with the stability of PSCs, and the effect of annealing temperature of PRK layer on performance of PSCs. Characterization of PSCs achieved by using X-ray diffraction, SEM, and Spectrophotometer techniques. The effect of annealing on the optical properties of MAPbI3 films were studied by measuring spectral transmittance. The energy band gap value of the MAPbI3 film was found to be 1.60 eV.

Synthesis of Bi2S3 thin films based on pulse-plating bismuth nanocrystallines and its photoelectrochemical properties.

The solubility of Bi3+ in aqueous solution is an important factor that limits the fabrication of high-quality Bi2S3 thin films. In order to find a low-cost method to manufacture high-quality Bi2S3 thin films, we are reporting the preparation of the Bi2S3 thin films based on pulse-plating method in this paper for the first time. The nano-bismuth particles were obtained by electroplating on fluorine-doped SnO2 (FTO)-coated conducting glass substrates with saturated bismuth potassium citrate solution as the electroplating bath, and then it was put into a muffle furnace to oxidize. Finally, the thin films depositing on FTO glass substrates were put into the thioacetamide solution for vulcanization. In the end, the Bi2S3 thin films were successfully prepared on FTO glass substrates. Different characterization techniques were used to characterize the structure, morphology and photoelectrochemical properties of the prepared thin films. The test results revealed that we used this method to synthesize the high-quality Bi2S3 thin films, thus the Bi2S3 materials synthesized through this method are promising candidates in photoelectrochemical application.

STUDY OF THE Ni(OH)2 ELECTROCHROMIC PROPERTIES OF FILMS DEPOSITED ON FTO GLASS WITH AN ADDITIONAL CONDUCTING LAYER

This work attempts to evaluate the influence of substrate conductivity on electrochromic and electrochemical properties of Ni(OH)2/PVA composite films, including coloration and bleaching rate. The conductivity of FTO glass was improved by depositing a silver gird with differing line densities. For deposition of the silver lines, aerosol jet printing method was used. As a result, few electrochromic films were deposited onto bare FTO glass and FTO glass with silver grid deposited onto it. In order to investigate deposited electrochromic films, the cyclic voltammetry with simultaneous recording of the optical characteristics is used. The optical characteristics of films were rather close to each other. At the same time, their electrochemical properties are different. It is found that the additional peaks observed is that of silver, which is electrochemically active in used potential window. In addition it was observed that during electrochemical cycling of Ni(OH)2/PVA deposited on substrates with silver grid, the last changed color from shiny metallic to black color. It is proposed that color changes of silver grid caused by silver transforming to Ag2O or AgO and back to metallic silver. It is found, that for small areas of electrochromic platings, substrate resistivity has a negligible effect on coloration and bleaching rates. The coloration and bleaching rates for Ni(OH)2/PVA films deposited onto the bare substrate, the substrate with a silver grid (1 cm cell size) and the substrate with a silver grid (0.5 cm cell size) were: –1.45, –1.71, –1.40 and 1.1, 0.75, 0.84 %∙s-1. It is suggested that the effect of substrate conductivity will clearly be seen when the physical sizes of substrate increase. Also it was underlined that for further experiments for effect definition of substrate resistivity on electrochromic properties inherit conductive materials should be used

Synthesis and study of photoelectrical properties of planar ensembles based on TiO2 and graphene oxide

In this paper, planar structures of various configurations based on TiO2 and graphene oxide are synthesized. Using SEM, it is shown that graphene oxide forms an insular film both on the surface and under the TiO2 layer during deposition. As well as SEM images show that TiO2 nanoparticles on the surface of graphene oxideare distributed as evenly as on the surface of FTO glass. The absorption spectra of synthesized films are a combination of the absorption curves of the original components. In this case, there is a shift of the absorption band of the planar structure nanocomposite to the longwave region. It is shown that in planar ensembles, the photoelectrochemical activity of films is higher only for the first lighting cycle. Research shows that the amount of graphene oxide affects not only the optical and photoelectrochemical properties, but also the electrical parameters. The latter, in turn, show that the resistance decreases by 1.3 times in the planar structure of graphene oxide with 30 layers. It was found that in planar structures of nanocomposite materials, the location of graphene oxide also affects the overall properties of the material. Research shows that the best indicators of photoinduced current generation are registered for the FTO/GO/TiO2 structure. Thus, a nanocomposite material in a planar structure based on TiO2 and graphene oxide depends on the architecture of the location and deposited volume of graphene oxide.

Sn-doped TiO2 nanotubular thin film for photocatalytic degradation of methyl orange dye

We fabricated Sn-doped TiO2 nanotubular film via annealing of anodized TiO2 nanotubes grown on F–SnO2 (FTO) glass. Annealing was carried out at 500 °C in ambient air. Anatase crystal structure was achieved with no change in nanotubular morphology in respect to as-anodized amorphous TiO2 nanotubes. The X-ray photoelectron spectroscopy analysis revealed Sn on the surface of TiO2 film, following the thermal treatment, probably caused by the diffusion from FTO glass. Depth profile examination of the film chemical composition was conducted by elastic recoil detection analysis, which showed that in addition to the diffusion of Sn from FTO, diffusion of Ti to FTO concurrently occurred. Thus, a higher concentration of Sn was found at the bottom of the tubes, while a lower concentration was present on the tubes’ surface top. This explains the improved optical response revealed by a diffuse reflectance spectroscopy. The absorption enhancement demonstrated that Sn-doped TiO2 film was efficient in the degradation of methyl orange dye under visible light.

Synthesis and characterization of platinum multi-walled carbon nanotubes nanocomposite film electrode

Carbon nanotubes (CNTs) were synthesized by a bimetallic (Fe–Co/CaCO3) catalytic chemical vapour deposition (CCVD) method. The synthesized CNTs were purified with acid to remove the catalyst impurities to enhance the deposition of platinum (Pt) onto the CNTs surface. Platinum multiwall (Pt-MWCNTs) nanocomposites were produced by a wet impregnation technique dispersed in Texanol and Acrylic resins to form a paste. The paste was screen printed on an FTO glass substrate. Surface morphology, microstructure, chemical composition, crystallographic phase, surface area and electrical performance of the Pt-MWCNTs nanocomposites were measured by HRSEM, HRTEM, EDS, XPS and XRD. The electrical conductivity of the electrode produced was found to be 4.927 S m−1. The results showed that the prepared nanocomposites will be a good electrode material in solar cell applications.

High stable with efficient dye-sensitized solar cell-based Al2O3/graphene hybrid photoanode fabricated by simple household microwave irradiation technique

A facile and one-step microwave irradiation approach was adapted to fabricate the hybrid photoanode of aluminum oxide (Al2O3)/graphene (GR) nanocomposite and scientifically investigated their structural, morphological and optical properties by XRD, TEM, Raman, UV, PL and BET analysis. XRD and TEM results exposed that crystal symmetry and exhibited face centered lattice with uniform plate-like nanoparticles are homogeneously covered on the surface of the graphene sheets. Mesoporous with nature with high pore size and huge surface area of Al2O3/GR is identified by N2 adsorption–desorption analysis. A significant reduction in the band gap energy (4.42–3.62 eV) and rapid electron–hole pair generation process of the hybrid materials was found by UV-DRS and PL spectra analysis. Sandwich type solar cell was fabricated by deposition the hybrid materials on FTO glass substrate and technically studied the photovoltaic (PV) parameters through J–V characteristics. The results express that Al2O3/GR hybrid photoanode show fabulous photo conversion efficiency (PCE) of (8.21%) and high stability than compared with bare Al2O3.

Nanostructured Mixed Transition Metal Spinel Oxide Thin Films As Efficient Electrocatalysts – Composition, Structure and Properties

Transition metal oxides have received renewed attention with their demonstrated usefulness as cathodes in dye-sensitized solar cells and as anodes in fuel cell [1,2]. In addition, careful choice of the synthesis method and experimental conditions allow for the tailoring of the film nanostructure and surface area. However, it is clear from the literature [3,4] and our own work [5,6] that the experimental parameters used for the oxide material preparation can greatly affect its electrocatalytic properties and this often makes it difficult to compare material performances. We have prepared various spinel oxides, namely CuxCo3-xO4 (0 ≤ x ≤ 1), Ni1-xCuxCo2O4 (0 ≤ x ≤ 0.75) and FeyNix-yCo3-xO4 (for y = 0.1 and 0.15 and x = 1 and 0.5, respectively), on FTO glass using the thermal decomposition method.The films were analyzed, using several structural, chemical and electrochemical methods such as x-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX), cyclic voltammetry and X-ray photoelectron spectroscopy (XPS). The oxygen evolution reaction (OER) and electroreduction of hydrogen peroxide reaction were used as model reactions to determine the electrocatalytic activity of the electrodes.The SEM analysis shows that the prepared thin films are quite porous and uniform. EDX analysis shows that a good correlation exists between stoichiometric and the resulting composition of the films. CuxCo3-xO4 materials shows a tendency for more copper to be incorporated in the films, while for Ni1-xCuxCo2O4, an excess of Co and a deficiency of Cu is observed. The formation of the spinel structure is confirmed by XRD analysis. For CuxCo3-xO4, an increase of the lattice parameter with increasing copper content was observed. This supports the incorporation of the copper in the spinel structure. However, the increase of the lattice-parameter was not linear due to the formation of copper oxide at higher copper concentrations. For the Ni1-xCuxCo2O4 series, the X-ray data also support the existence of the spinel structure.Using the film's real surface area, as determined by capacitance measurements, it is possible to compare the properties of materials of different roughness. The addition of Cu to Co3O4 to form CuxCo3-xO4 resulted in an increase in roughness for x values from 0.25 to 1. When Ni is added to form the ternary oxides, the roughness more than doubles. For spinel oxides containing iron, nickel and cobalt, the roughness is much lower, i.e., around 80.X-ray Photoelectron Spectroscopy was used extensively to understand cation site occupancy, composition and oxidation state of the metal ions in the ternary oxide materials. Our XPS data shows some differences between the bulk and surface compositions of our materials. The high-resolution spectra for the Co, Cu and Ni 2p peaks indicate the existence of different Co2+/Co3+, Cu+/Cu2+ and Ni2+/Ni3+ ratio for these materials. However, the amount of iron was often too small to be detected by XPS in iron containing samples with y ≤ 0.15. In general, the surface of the materials was found to be enriched with copper and deficient in cobalt. Larger Co2+/Co3+ ratios are usually associated with better electrocatalytic properties towards OER. This points to the octahedral surface sites being the active sites. The analysis of O 1s spectra indicates that it is composed of three components that can be assigned to lattice oxygen, adsorbed oxygen containing species such as hydroxides and surface bonded water.During the presentation, our results will be compared to the morphology, structure, surface and bulk compositions, and electrochemical properties of spinel oxide films of similar compositions reported in the literature.

Fabrication of Nanosticks-Like CdS Sensitizer for the Application of Solar Cells.

The novelty of this work is to fabricate the Nanosticks (NSs) like CdS sensitizer on the surface of TiO₂ electrode by chemical bath deposition (CBD) method with a very high vacuum annealed at 350 °C for 30 min. Whereas, nanocrystalline TiO₂ electrodes have been prepared on FTO (SnO₂: F) glass by a spin-coating method with high purity (99.99%, Degussa P25) TiO₂ powder. The surface of the CdS layer has been covered by NSs like structures which are confirmed by the scanning electron microscope image. The 100 nm of platinum-coated FTO substrate and polysulfide-based electrolyte are used to assemble the Grätzel Solar cell (GSC). The performance of solar cell (SC) based on NSs like CdS has been compared with the nanoparticles (NPs) based CdS sensitized SC, where CdS NPs has synthesized by CBD without any post-annealing. The efficiency of NSs like CdS sensitized SC exhibits 2.44%, which is 2 folds of the efficiency of the CdS NPs sensitized SC. The NSs like CdS sensitized SC shows the highest photocurrent 20.24 mA/cm² compared to CdS NPs based SC.

Organic/Inorganic Hybrid Electrode Materials for Photo-Conversion of Solar Energy

NiO nanoparticles deposited on FTO glass modified surface were used to adsorb an organic dye. The obtained device was covered with PEDOT/PSS polymers blend and later sprinkled with palladium nanoparticles.This modified hybrid electrode was used under ligth and than under dark conditions to study the reduction reaction of CO2 in solution.The results obtained indicated a large shift toward positive potential of the reduction wave of CO2 in solution under light when compared to the same reduction wave under dark in the same conditions.The obtained results will be presented and discussed in the frame of the state of the art of CO2 reduction catalysed by palladium nanoparticles supported by hybrid charge transport material.

Synthesis of Zinc-Terephthalate Metal Organic Frameworksand Their Application to Redox Batteries

Metal-organic frameworks (MOFs) made of inorganic ions and organic linkers are attracting attention for their unique properties because of their widely open porous crystal structure. We have recently succeeded in microwave-assisted hydrothermal synthesis of Zn-Terephthalate (TPA) MOF particles [1]. Several different types such as Zn3(OH)4(TPA)･6H2O (Type I) and Zn4(OH)6(TPA) (Type II) in layered structures were obtained depending on pH of the precursor solution. They exhibited proton-selective reversible redox reactions to indicate possibilities for membrane-free redox batteries [2]. However, still little is known about their electrochemical behavior (such as redox potential, coulombic capacity, cycle stability, and their difference between I and II). In this study, we have undertaken quantitative electrochemical analysis at the Zn-TPA MOF electrodes to evaluate their applicability to batteries. The precursor solution containing 0.1 M zinc acetate and 0.05 M TPA was basified to pH 7.0 and 5.9 to yield Types I and II, respectively. White precipitates after hydrothermal reaction at 150℃ and 30 min. under microwave irradiation were centrifugally collected. 35wt% of MOF pastes were prepared in 2-butanol containing acetylacetone, coated onto an FTO glass substrate to fabricate porous electrodes with a projected area of 2 cm2. While the film thickness for both Types I and II was about 10 µm, the density was 0.25 and 0.45 g cm-3, corresponding to porosity of 90 and 82%, respectively, assuming the density of bulk MOFs of Types I and II to be the same as that of Zn3(OH)4(TPA) reported earlier (2.538 g cm-3) [3]. The redox potentials of Types I and II were -1.16 and -1.08 V vs. Ag/AgCl in a neutral KCl aq. as judged from redox peaks in cyclic voltammograms (CVs, Fig. 1). Although Type II initially exhibited the higher redox activity than Type I, it gradually decreased over the repetition of CVs, whereas coulombic reversibility always was around 100% (Fig. 1). Thus, the redox active fraction calculated by assuming redox reactions as, Zn3(OH)4(TPA)･6H2O + 2H+ + 2e- ⇌ Zn3(OH)4(TPAH2)･6H2O (1) Zn4(OH)6(TPA) + 2H+ + 2e- ⇌ Zn4(OH)6(TPAH2) (2)was about 0.22% for Type I and stayed unchanged, whereas it dropped from 0.89% (initial) to 0.50% (100th cycle) for Type II. In fact, the XRD pattern of Type II electrode after 100 CV cycles revealed its conversion into Type I, described as, Zn4(OH)6(TPA) + 2H+ + 2e- + 6H2O → Zn3(OH)4(TPAH2)･6H2O + Zn(OH)2 (3)Although Type I appears to be the better electrode material for its more negative potential and higher stability, the absolute redox capacity is so small because of its small redox active fraction. That may be caused by poor necking of the particles as suggested from its extremely high porosity. Therefore, control of particle size, conditions of paste preparation and film fabrication need to be reviewed to improve its redox activity.[1] Y. Hirai et al., Microsys. Technol., 24, 699–708 (2017)[2] Y. Hirai et al., ECS Trans., 88(1):259-268 (2018)[3] A. Carton et al., Solid State Sciences., 8 (2006) 958–963 Figure 1