TiO2 Working Electrode Research Articles

Inexpensive green synthesis of natural dye-sensitized solar cells with aqueous solution as a Bi2S3 counter electrode

Natural dyes are more environmentally and fiscally friendly than ruthenium-based dyes because they are non-toxic and inexpensive. In this research, dye-sensitized solar cells (DSSCs) were created using natural dyes as light harvesting materials. Natural dyes were derived from blackberry fruit, beetroot, and neem foliage. Also, organic-solvent and water-based electrolytes were investigated for the TiO2 working electrode and Bi2S3 counter electrode. As-prepared organic-solvent-based electrolyte DSSCs demonstrated photoelectrochemical efficiency with fill factors (FF) varying from 35% to 45%. At 100 mW/cm2 light strength, open circuit voltages (VOC) and short circuit current densities (JSC) vary from 0.41 to 0.58 V and 1.35–1.93 mA cm−2, respectively. As a result of this, the highest power conversion efficiency (ƞ) of the as-prepared blackberry DSSC is 0.51%. The highest power conversion efficacy using water-based electrolytes with berries dye and a comparable extraction solvent, on the other hand, reached up to 0.47%. This is the first research to describe the construction of a dye-sensitized solar cell using natural dye sensitizers extracted from various colours of fruit and foliage in the presence of organic-solvent and aqueous electrolyte with Bi2S3 as a counter electrode for an efficient dye-sensitized solar cell.

Fabrication and Properties of Graphene Electron Multiple Transporting Layers for Dye-Sensitized Solar Cell

To investigate the optimal working electrode for dye-sensitized solar cells (DSSCs), the traditional TiO2 film is modified by adding an electron transporting layer of graphene. Different layers of TiO2/graphene/TiO2 stacks on the FTO substrate are analyzed. The experimental results show that the TiO2/graphene/ TiO2/graphene/TiO2 (TGT2) structure has higher dye loading, which means that more dye molecules can increase the light absorption. In the electrochemical impedance spectroscopy (EIS) analysis, the TGT2 structure has a lower interfacial resistance ( R ct2) of 2.35 Ω at the TiO2/dye/electrolyte interface and a higher electron lifetime (τe) of 64.28 ms. This result represents that the graphene material exerts its properties of good conductivity and high charge carrier mobility to reduce the interfacial resistance and enhance the electron transport capability. The DSSCs with TGT2 structure working electrode has the short circuit current density ( J SC) of 10.87 mA/cm2 and photovoltaic conversion efficiency (η) of 4.47%. In this study, the working electrode of DSSC is successfully modified by using a TGT2 structure, with an improved efficiency of 10.6% and short circuit current density ( J SC) of 17.7% higher than that of the TiO2 working electrode.

Electrochemical Generation of Hydrogen and Methanol using ITO Sheet Decorated with Modified-Titania as Electrode

Current issues of global warming and environmental pollution due to extensive use of fossil fuels has been reached to an alarming position. Being CO2 as main byproduct of fossil fuel consumption and water as abundantly available on earth surface has great potential to replace fossil fuels as energy source. Herein, electrocatalytic CO2 reduction with water for methanol and hydrogen gas (H2) production over ITO sheet decorated with modified-Titanium nanorods (TiO2 NR), has been investigated. The performance comparison of electrocatalytic activity of hydrothermally modified-titania with commercial TiO2 microparticles (MP) were further investigated. Electrochemical reactor containing KHCO3 aqueous solution with CO2 as an electrolyte and modified TiO2 nanorods (NR) as working electrodes offer an eco-friendly system to produce clean and sustainable energy system. The typical rates of product, i.e. methanol and H2 generation from the ITO sheet decorated with modified TiO2 NR layer recorded higher than those for the ITO sheet with commercial TiO2 microparticle. At 2.0V applied potential vs Ag/AgCl as reference electrode, the modified TiO2 NR electrocatalyst yielded methanol at a rate of 3.32 µmol.cm−2.L−1 and H2 at a rate of 6 µmol.cm−2.L−1 which was higher than that of commercial TiO2 MP electrocatalyst (methanol = 1.5 µmol.cm−2.L−1 and H2 = 3.7 µmol.cm−2.L−1). The enhancement in product yields of methanol and H2 was mainly due to the notable improvements and modification in texture of TiO2 working electrode interface. Hence, it is concluded that the modified TiO2 NR can be considered as a competent candidate for sustainable energy conversion applications. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Analysis of charge transport properties of dye-sensitized solar cell (DSSC) with TiO2 working electrode by employing electrochemical impedance spectroscopy (EIS)

In this paper DSSCs of various electrode thicknesses (L = 3 ?m?12 ?m) are assembled using N719 dye, an iodide (I????)/triiodide (I???? ????) redoxliquid electrolyte and TiO2 (P-25) working electrode (WE). The theoretically modeled equations defining various bulk and interface impedances are incorporated with EIS spectrum analyzer software to fit the simulated EIS curves with experimentally measured EIS curves to evaluate the charger transfer and recombination properties of the assembled DSSCs. EIS fitting parameters investigated to study the impact of WE thickness on the charge transport properties of assembled DSSC. It is observed that the charger transfer resistance at TiO2/electrolyte interface (Rk) and series resistance (Rs) are reduced from 8 ?cm2 ? 4.05 ?cm2and 14.5 ?cm2?10.06 ?cm2 respectively which shows consistency with improvement in electron life time (?e) from 5.8 ms ?12.4 ms for increasing WE thickness, L = 3 ?m?12 ?m. The combined impact of significant reduction in Rk and Rs along with improved trend of ?e can be considered as major factors for efficient electron injection across Dye/TiO2 interface hence increases short circuit current (Isc) from 1.485 mA ? 2.365 mA and photovoltaic conversion efficiency (?) from 3.55 % ? 5.46 % for L = 3 ?m?12 ?m, respectively. Moreover, a remarkable increment in ? (~45%), ?e (~56.3%) and a noticeable reduction in Rk(~38.75 %), Rs (~23.8 %) are observed for WE variations (L = 3 ?m?6?m) and further shows insignificant change for thicker WE (L> 6?m)

Increasing the Efficiency of Dye-Sensitized Solar Cells by Adding Nickel Oxide Nanoparticles to Titanium Dioxide Working Electrodes

In this study, nickel oxide (NiO) nanoparticles were added to a titanium dioxide (TiO2) nanoparticle paste to fabricate a dye-sensitized solar cell (DSSC) working electrode by using a screen-printing method. The effects of the NiO proportion in the TiO2 paste on the TiO2 working electrode, DSSC devices, and electron transport characteristics were comprehensively investigated. The results showed that adding NiO nanoparticles to the TiO2 working electrode both inhibited electron transport (a negative effect) and prevented electron recombination with the electrolyte (a positive effect). The electron transit time was extended following an increase in the amount of NiO nanoparticles added, confirming that NiO inhibited electron transport. Furthermore, the energy level difference between TiO2 and NiO generated a potential barrier that prevented the recombination of the electrons in the TiO2 conduction band with the I3- ions in the electrolyte. When the TiO2–NiO ratio was 99:1, the positive effects outweighed the negative effects. Therefore, this ratio was the optimal TiO2–NiO ratio in the electrode for electron transport. The DSSCs with a TiO2–NiO (99:1) working electrode exhibited an optimal power conversion efficiency of 8.39%, which was higher than the DSSCs with a TiO2 working electrode.

Sol-Gel Processed TiO2 Nanotube Photoelectrodes for Dye-Sensitized Solar Cells with Enhanced Photovoltaic Performance.

The performance of dye-sensitized solar cells (DSCs) critically depends on the efficiency of electron transport within the TiO2-dye-electrolyte interface. To improve the efficiency of the electron transfer the conventional structure of the working electrode (WE) based on TiO2 nanoparticles (NPs) was replaced with TiO2 nanotubes (NTs). Sol-gel method was used to prepare undoped and Nb-doped TiO2 NPs and TiO2 NTs. The crystallinity and morphology of the WEs were characterized using XRD, SEM and TEM techniques. XPS and PL measurements revealed a higher concentration of oxygen-related defects at the surface of NPs-based electrodes compared to that based on NTs. Replacement of the conventional NPs-based TiO2 WE with alternative led to a 15% increase in power conversion efficiency (PCE) of the DSCs. The effect is attributed to the more efficient transfer of charge carriers in the NTs-based electrodes due to lower defect concentration. The suggestion was confirmed experimentally by electrical impedance spectroscopy measurements when we observed the higher recombination resistance at the TiO2 NTs-electrolyte interface compared to that at the TiO2 NPs-electrolyte interface. Moreover, Nb-doping of the TiO2 structures yields an additional 14% PCE increase. The application of Nb-doped TiO2 NTs as photo-electrode enables the fabrication of a DSC with an efficiency of 8.1%, which is 35% higher than that of a cell using a TiO2 NPs. Finally, NTs-based DSCs have demonstrated a 65% increase in the PCE value, when light intensity was decreased from 1000 to 10 W/m2 making such kind device be promising alternative indoor PV applications when the intensity of incident light is low.

Interface effect of graphene–TiO2 photoanode with CuO nanorod counter electrode on solar conversion efficiency and enhanced external quantum efficiency

In this study, graphene–TiO2 nanostructures and CuO nanorods were produced on FTO (F:SnO2) substrates using the cost effective hydrothermal growth method. The interface effects of the graphene–TiO2 nanostructures were examined to compare with pure TiO2 photoanode in respect to solar cell efficiency. Graphene–TiO2 was shown as a perfect alternative for the standard F:SnO2 (FTO)/TiO2 working electrodes in dye-sensitized solar cells due to its higher electro-optic activity, surface area and good charge transport characteristics. Furthermore, CuO nanorods were also investigated as efficient counter electrodes (CEs) to be used in place of the conventional and costly platinum (Pt) CEs. By utilizing graphene–TiO2 photoanode and CuO nanorod based CEs, hybrid solar cells with photovoltaic efficiency of 6.18% under AM 1.5G solar radiation were produced. According to the external quantum efficiency (EQE) of the hybrid solar cell agreement with the J–V measurements, the device based on the hybrid CuO CE exhibited higher EQE. EQE was improved by 30% compared to the Pt CE due to the higher Jsc, Voc and the fill factor of the hybrid devices.

Effect of Titanium Dioxide (TiO2) Light Scattering Layer deposited by Spray Deposition Method at Room Temperature for Dye-sensitized Solar Cell (DSSC)

Abstract TiO2 light scattering layer was prepared form TiO2 (Degussa P25) colloidal solution of 0.75% by Wt. by spray coating machine under O2 gas. The conditions were varied with pulse spray at 5, 10, 15 and 20 times under substrate rotation deposited on the nano-porous TiO2/FTO substrate. The TiO2 working electrodes were sintered at 500°C for 1 hour and lead to immersed in dye sensitizer for 24 hours. Morphological, structural and optical properties were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and UV-vis spectrophotometer, respectively. DSSC cells were fabricated by the TiO2 working electrodes sandwich with the Pt counter electrode. Photo-conversion efficiency of DSSC cells were compared between the standard cells which non-TiO2 scattering layer and the TiO2 scattering layer by solar simulator (AM 1.5). Structural characteristic exhibits crystalline of anatase phase TiO2 plane (101). Surface morphology is beginning uniform distribution when the pulses spray since to 15 times and obtains nano-microparticles sizes. Moreover, thickness of TiO2 light scattering layer and TiO2 working electrodes have approximately of 1 to 1.5 µm and 10 to 20 µm. Transmittances spectra of have lower 50%. Reflections spectra have lower of 50% and absorbance can be absorbed of 1 to 2% show that low transmittance, low reflection and low absorption in visible light which occur light scattering effect in TiO2 scattering layer well. The efficiency can be highest obtains which consists of the open circuit voltage (Voc), the current density (Jsc), fill factor.

Porous composite separator membranes of dye-sensitized solar cells with flexible substrate for their improved stability

The durability of a dye-sensitized solar cell with flexible substrate (fDSSC) was improved by introducing a composite separator membrane (CSM) between the TiO2 working electrode and the counter electrode (CE). The fDSSC was fabricated by replacing a typical fluorine-doped tin oxide glass substrate of the platinum CE with a flexible indium tin oxide-coated poly(ethylene naphthalate) substrate. The CSM was a triple-layered membrane composed of poly(ethylene terephthalate) nonwoven fabric between the poly(vinylidene fluoride-co-hexafluoropropylene) gel layers, which provided a sandwich-like structure. The fDSSC with the CSM exhibited relatively good electrolyte retention capability and improved interfacial contact between the components, affording an fDSSC with high energy conversion efficiency and stable long-term performance. The potential of a CSM as an efficient component for durable flexible energy devices is demonstrated.

Performance of 7-cells Dye Sensitized Solar Module in Z-type Series Interconnection

Dye sensitized solar cells (DSSC) is becoming attractive research topic as third generation solar cells technology since it provides clean energy and low cost fabrication. In this study, DSSC was fabricated into module scale, which is important for practical applications. The module was prepared in sandwich structure consisting of TiO2 working electrode and Pt counter electrode on conductive substrate with an area of 100 mm x 100 mm, which was distributed into seven active cells. TiO2 paste was deposited on FTO glass as working electrode with a size of 10 mm x 98 mm per unit cell by screen printing method. Each cell was connected in Z-type series that able to produce high voltage. I − V measurement was applied in two methods consisting of laboratory testing using sun simulator under 500 W/m2 of illumination and outdoor testing using a digital multimeter under direct sunlight. The result shows that DSSC module has photoconversion efficiency of 1.08% and 1.17% for laboratory and outdoor testing, respectively. The module was also tested in three different times to monitor its stability performance.

Material analysis and characterization of working electrodes of dye-sensitized solar cells

The aim of this paper is to demonstrate the influence of the TiO2 with different sintered time regarding the performance of photovoltaic characteristics of DSSCs. A layer of TiO2 with a thickness of ~8-10 μm and an area of 0.25 cm2 was prepared by depositing TiO2 nanoparticles paste onto a fluorine-doped tin oxide (FTO) sbustrate by doctor blade technique, followed by sinterring at 450°C with 4 differennt sintering times: 10 min, 20 min, 30 min, and 40 min. The Pt solution was dripped on FTO substrate works as counter electrode. SEM, XRD and I-V curve were conducted for the material analysis. The photovoltaic characteristics were measured under AM 1.5 sunlight simulator. The results reveal that the different sintered time of TiO2 working electrode did affect the photovoltaic conversion efficiency. In conclusion, TiO2 sintered for 30 min yields the highest power conversion efficiency of 6.273%.

Enhance photovoltaic performance of tris(2,2′-bipyridine) cobalt(II)/(III) based dye-sensitized solar cells via modifying TiO2 surface with metal-organic frameworks

A very thin blocking layer of a metal organic framework ZIF-8 has been successfully coated on the surface of mesoporous TiO2 films. Compared to the uncoated samples, dye-sensitized solar cells with such films exhibit enhanced open circuit voltage (VOC) and short circuit current (JSC) by 3% and 21%, respectively, leading to a 9.42% energy conversion efficiency using tris(2,2′-bipyridine) cobalt(II)/(III) redox mediator. The electron lifetimes as well as dye loading on TiO2 working electrodes were found to increase after ZIF-8 treatment, which is responsible for the improvement of JSC. An increase of charge recombination resistance between working electrode and organic electrolyte, as is characterized by electrochemical impedance spectra, is proposed to be the reason for the increased VOC, as there is no TiO2 conduction band shift after the treatment of ZIF-8.

Fabrication of working and counter electrodes on plastic substrates for flexible dye-sensitized solar cells

This paper presents the fabrication technologies related to flexible titanium-dioxide (TiO2) working electrodes and graphite counter electrodes on plastic substrates for dye-sensitized solar cells (DSSCs). The DSSC on a plastic substrate had a sandwich structure consisting of a TiO2 working electrode, an electrolyte, and a graphite counter electrode. Nano-crystalline TiO2 powder, titanium (IV) bis (ammonium lactato) dihydroxide (TALH), de-ionized water (DI water), and Triton X-100 were added to the mixture of PDMS base and curing agents to form TiO2 colloids for the TiO2 working electrode. The material analysis of the TiO2 working electrode and the graphite counter electrode employed field-emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), and X-ray diffraction (XRD). Nano-crystalline TiO2 powder was used to form the TiO2 working electrode. The surface characteristics of the TiO2 and graphite films were investigated herein. The low-cost fabrication technologies of the TiO2 working electrode and graphite counter electrode on the plastic substrate were clearly demonstrated.

Influence of thin film thickness of working electrodes on photovoltaic characteristics of dye-sensitized solar cells

This paper presents the study of the influence of thin film thickness of working electrodes on the photovoltaic characteristics of dye-sensitized solar cells. Titanium dioxide (TiO2) thin films, with the thickness from 7.67 to 24.3 μ m, were used to fabricate the working electrodes of dye-sensitized solar cells (DSSCs). A TiO2 film was coated on a fluorine-doped tin oxide (FTO) conductive glass substrate and then sintered in a high-temperature furnace. On the other hand, platinum (Pt) solution was coated onto an FTO substrate for the fabrication of the counter electrode of a DSSC. The working electrode immersed in a dye, the counter electrode, and the electrolyte were assembled to complete a sandwich-structure DSSC. The material analysis of the TiO2 films of DSSCs was carried out by scanning electron microscopy (SEM) and ultraviolet-visible (UV-Vis) spectroscopy, while the photovoltaic characteristics of DSSCs were measured by an AM-1.5 sunlight simulator. The light transmittance characteristics of the TiO2 working electrode depend on the TiO2 film thickness. The thin film thickness of the working electrode also affects the light absorption of a dye and results in the photovoltaic characteristics of the DSSC, including open-circuited voltage ( V OC), short-circuited current density ( J SC), fill factor, and photovoltaic conversion efficiency.

Few-layered graphene decked with TiO2 nano particles by ultrasonic assisted synthesis and its dye-sensitized solar cell application

Few-layered graphene (FLG, 1.0, 2.0 and 3.0 wt%)/titania (TiO2) nanocomposites were prepared by ultrasonic assisted synthesis. The phase and compositional analysis of FLG/TiO2 nanocomposites were performed with X-ray diffraction and Raman spectroscopy, optical properties carried out by UV–Vis diffuse reflectance spectra and functional groups identified by Fourier transform infrared spectroscopy. Surface morphologies were characterized by field emission scanning electron microscopy and high-resolution transmission electron microscopy. The prepared FLG/TiO2 nanocomposites were used as working electrodes to form thin films deposited onto fluorine doped tin oxide through a doctor blade technique. The assembled solar cell, current density–voltage characteristics were measured with N719 dye under AM 1.5G, 100 m W/m2 of the solar simulator. The efforts showed that the optimized η was observed to be 6.70 % in appropriate with FLG (1.0 wt%)/TiO2 working electrode, compared to the TiO2 working electrode. However, by increasing wt% of FLG the η was decreased due to the surface interaction of FLG with TiO2 NPs. The results revealed that the FLG (1.0 wt%)/TiO2 working electrode has increased the electron charge transport rate which further leads to enhanced η of DSSC.

Fe‐Cu metastable material as a mesoporous layer for dye‐sensitized solar cells

AbstractThis study investigates the performance of dye‐sensitized solar cells constructed with a Fe‐Cu metastable material as the mesoporous layer on which a natural organic dye is applied. The synthesis of the Fe‐Cu material is done via a high throughput process that produces nanosized particles from elemental metallic powders. Xanthophyll is singled out as the organic natural dye of choice among other dyes that were extracted, as it exhibited wider spectral absorptivity in terms of wavelength range and magnitude. Two compact solar cells were constructed and tested; one is a reference cell with a TiO2 working electrode and the other with a Fe‐Cu working electrode. The results show a better power conversion efficiency for the Fe‐Cu‐based solar cell 0.943% compared to 0.638% for the TiO2, and the number of carriers in the former is found to be orders of magnitude higher than the latter (1019 vs. 1032, respectively). A thorough optical, electrical, and thermal analysis of the Fe‐Cu material is conducted and used to explain the obtained results.

Effects of CdS-TiO<sub>2</sub> Working Electrode Layer on Dye Sensitized Solar Cell Investigated by Impedance Spectroscopy

The efficiency of dye-sensitized solar cell (DSSC) has been improved by various ways. In this work, The CdS nanoparticles were added in the TiO2 working electrode for improving the efficiency of DSSC. The DSSC structure comprises of TiO2 working electrode with and without CdS powder, Pt counter electrode, rutherium (II) (N719) dye and lithium iodide electrolyte. Normally, the TiO2 paste was screened for five layers. In this work, the TiO2 paste with CdS nanoparticles was screened for various numbers of layers on the layers of pure TiO2 to get the total of five layers. Then TiO2 mixed and unmixed CdS nanoparticles and Pt films were annealed at the temperature of 500°C for 50 min. Impedance spectroscopy (IS) was used to study charge transport in each interface of DSSC. For illumination condition, the measured IS can be divided into three regions that were charge transport at Pt layer, charge transport at working electrode/dye/electrolyte interface and ion contribution at electrolyte layer. The carrier transport parameters extracted from fitting IS spectra were chemical capacitance, charge transfer resistance and time constant.

Enhancing the efficiency of dye-sensitized solar cells by adding diatom frustules into TiO2 working electrodes

In this study, diatom frustules were added into TiO2 paste to prepare a TiO2-diatom paste mixture. Spin-coating and high-temperature sintering techniques were then used to fabricate working electrodes for dye-sensitized solar cells (DSSCs). Mixing the diatom frustules with the TiO2 paste improved the light-trapping effect and scattering properties of the incident light in the TiO2-diatom working electrodes, thereby enhancing the power conversion efficiency of the DSSCs. In this study, a high-speed centrifugal processing technology and sedimentation-rate separation techniques were first used to obtain the diatom frustules, which were then mixed with the TiO2 paste at a weight ratio of 1:50; a spin-coating technique was then used to fabricate the working electrodes. Finally, a high-temperature sintering process (500°C) was performed. In this study, optical microscopy, scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and a surface profiler and spectrometer were used to analyze the characteristics of the working electrodes. The TiO2 or TiO2-diatom working electrodes were prepared under various spin-coating conditions for fabricating and analyzing the characteristics of the DSSCs. The results indicated that under identical conditions, the power conversion efficiency of the DSSCs was 3.81% when coated three times with a conventional TiO2 paste, and 5.26% when coated once with the TiO2-diatom paste before being coated twice again with the TiO2 paste, indicating a 38% increase in efficiency.

Mesoporous TiO2 Microbead Electrodes for Cobalt-Mediator-Based Dye-Sensitized Solar Cells

Light scattering, porosity, surface area, and morphology of TiO2 working electrode can affect the power conversion efficiency of dye -sensitized solar cells dramatically. Here mesoporous TiO2 microbeads were tested as working electrode in dye-sensitized solar cells based on cobalt tris-bipyridine electrolyte. Power conversion efficiencies up to 6.4% were obtained with D35 dye adsorbed onto the light-scattering microbeads. Electron transport, studied using small light perturbation methods, was found to be significantly faster in the microbead films than in standard mesoporous TiO2 films. This was attributed to the favorable assembly of nanocrystals in the microbeads, which can increase the electron diffusion coefficient in the conduction band. Electron lifetimes were similar in both types of film. While solar cell performance of microbead films was comparable to that of standard mesoporous films in acetonitrile-based electrolytes, a significant improvement was found when the more viscous 3-methoxypropionit...

Influence of Scattering Layer on the Performance of Solid-State Dye Sensitized Solar Cell

Carbon counter electrode based solid-state dye sensitized solar cells (ss-DSCs) have been investigated with the influence of scattering ZrO2 layer. Compared with the traditional noble metal based ss-DSCs, the scattering layer, which lies between the titania working electrode and counter electrode, plays the roles of both insulator to isolate the carbon electrode from the TiO2 working electrode and reflector to enhance the light harvesting efficiency. The particle size of the ZrO2 presents the remarkable effect on the performance of the ss-DSC.