Fabrication Of Dye-sensitized Solar Cells Research Articles

Fabrication and Photovoltaic Properties of Dye-Sensitized Solar Cells Based on Graphene–TiO2Composite Photoelectrode With ZnO Nanowires

In this paper, the photoelectrode of dye-sensitized solar cell (DSSC) was fabricated into a double-layer structure on the fluorine-doped tin oxide glass, which was synthesized by a graphene oxide–titanium dioxide composite layer (GO–TiO2), and a zinc oxide nanowires (ZNWs) layer. The morphology and effects of double layer were investigated by the field emission scanning electron microscopy, UV-visible spectrometer, and solar simulator. The enhancement of the photovoltaic performances of DSSC could be attributed to the high specific surface area of GO and high electron mobility of zinc oxide. Besides, the equivalent circuit and electrochemical properties of GO–TiO2/ZNWs double structure were also investigated by electrochemical impedance spectroscopy.

Efficient Solar Cells Based on Porphyrin Dyes with Flexible Chains Attached to the Auxiliary Benzothiadiazole Acceptor: Suppression of Dye Aggregation and the Effect of Distortion.

Donor-π-acceptor-type porphyrin dyes have been widely used for the fabrication of efficient dye-sensitized solar cells (DSSCs) owing to their strong absorption in the visible region and the ease of modifying their chemical structures and photovoltaic behavior. On the basis of our previously reported efficient porphyrin dye XW11, which contains a phenothiazine-based electron donor, a π-extending ethynylene unit, and an auxiliary benzothiadiazole acceptor, we herein report the syntheses of novel porphyrin dyes XW26-XW28 by introducing one or two alkyl/alkoxy chains into the auxiliary acceptor. The introduced chains can effectively suppress dye aggregation. As a result, XW26-XW28 show excellent photovoltages of 700, 701, and 711 mV, respectively, obviously higher than 645 mV obtained for XW11. Nevertheless, the optimized structures of XW26 and XW27 exhibit severe distortion, showing large dihedral angles of 57.2° and 44.0°, respectively, between the benzothiadiazole and benzoic acid units, resulting from the steric hindrance between the benzoic acid unit and the neighboring alkyl/alkoxy chain on the benzothiadiazole unit, and thus blue-shifted absorption, decreased photocurrents. and low efficiencies of 5.19% and 6.42% were observed for XW26 and XW27, respectively. Interestingly, XW26 exhibits a more blue-shifted absorption spectrum relative to XW27, indicating that the steric hindrance of the alkyl/alkoxy chains has a more pronounced effect than the electronic effect. Different from XW26 and XW27, XW28 contains only one alkyl chain neighboring the ethynylene unit, which does not induce obvious steric hindrance with the benzoic acid unit, and thus distortion of the molecule is not seriously aggravated compared with XW11. Hence, its absorption spectrum and photocurrent are similar to those of XW11. As a result, a higher efficiency of 9.12% was achieved for XW28 because of its suppressed dye aggregation and higher photovoltage. It is worth noting that a high efficiency of 10.14% was successfully achieved for XW28 upon coadsorption with CDCA, which is also higher than the corresponding efficiency obtained for XW11. These results provide a novel approach for developing efficient porphyrin dyes by introducing chains into the suitable position of the auxiliary benzothiadiazolyl moiety to suppress dye aggregation, without seriously aggravating distortion of the dye molecules.

Fabrication of green dye-sensitized solar cell based on ZnO nanoparticles as a photoanode and graphene quantum dots as a photo-sensitizer

Zero-dimensional graphene quantum dots (GQDs) consist of single- or few-layer graphene with a size less than 20 nm and stand for a new type of QDs with unique properties combining the graphene nature and size-resulted quantum effects. GQDs possess unique optical and electronic properties, and in particular possess a band-gap less than 2.0 eV because of quantum confinement and edge effects. In this study, we investigated the performance of DSSCs using different thicknesses of ZnO nanoparticles as a photo-anode and GQDs as a green photosensitizer. The current voltage (I-V) test results indicate that the performance of DSSCs is improved by increasing the thickness of the photo-anode and the thickness of 40 μm shows the highest efficiency for DSSC device based on ZnO nanoparticles photo-anodes. The DSSC using ZnO nanoparticles as a photo-anode with thickness of 40 μm shows almost same efficiency when we replaced N-719 with GQDs which is confirmed that using GQDs as an alternative to ruthenium based dyes is a new approach for DSSCs.

Electrochemical deposition of Pt-Ni on reduced graphene oxide as counter electrode material for dye-sensitized solar cell

Abstract In dye-sensitized solar cell (DSSC) alloys of Pt with other metals or replacement of it with Pt-free alloys can be used to reduce the fabrication cost. Herein, we present the formation of Pt-Ni alloy/reduced graphene oxide (Pt-Ni/RGO) counter electrode (CE) by a simple and environmental-friendly electrochemical deposition method for fabrication of DSSC. First, RGO/FTO CE was prepared through electrophoretic deposition (EPD) method and then reduced electrochemically. Then, Pt-Ni alloy was loaded on CE by cyclic voltammetry (CV) strategy. The morphology of the Pt-Ni/RGO film was characterized by field emission scanning electron microscopy (FESEM) analysis. Pt-Ni nanoparticles were uniformly dispersed on the surface of RGO after electrodeposition. The Pt-Ni/RGO CE showed remarkably enhanced electrocatalytic activities toward triiodide (I3−) reduction reaction in comparable to RGO CE. CV and electrochemical impedance spectroscopy (EIS) confirmed that the Pt-Ni/RGO CE has superior electrocatalytic activity than that of RGO and Pt-Ni CEs. The enhanced electrocatalytic activities can be in association with the synergistic effect of transition metals. As a result, an efficiency of 6.14% with Jsc = 14.08 mA cm−2, Voc = 749 mV, and FF = 0.58 was achieved for DSSC assembled with the Pt-Ni/RGO CE under AM 1.5 illumination of 100 mW cm−2. Thus, the fabricated Pt-Ni/RGO CE could be used as a promising material for a low-cost CE for DSSC.

In situ study of spray deposited titania photoanodes for scalable fabrication of solid-state dye-sensitized solar cells

Spray coating, a cost-effective and scalable technique, has been employed for fabricating titania films for solid-state dye-sensitized solar cells (ssDSSCs). The spray deposition of films is inherently based on kinetic processes with great complexity, which poses great challenges in its understanding. In the present work, the kinetics of the structure evolution of deposited films are investigated by in situ grazing-incidence small-angle x-ray scattering during spray deposition. The spray-solution is prepared via a polystyrene-block-polyethylene oxide (PS-b-PEO) template assisted sol-gel synthesis. It is turned into nanostructured titania/PS-b-PEO composite films via spray deposition. The information about nanostructure length scales of the composite film is obtained in real-time and in situ, revealing the morphological evolution during the spray deposition. The resulting mesoporous titania films serve as photoanodes of ssDSSCs, which couple with the solution-cast hole transport layer to form the active layers. The well working ssDSSCs demonstrate the successful use of spray deposition as a large-scale manufacturing process for photoanodes.

From Cell to Module: Fabrication and Long-term Stability of Dye-sensitized Solar Cells

Dye-sensitized solar cell (DSSC), which has been firstly developed by Graetzel et al back in 1991, has attracted a considerable interest since its discovery. However, two of the main challenges that the DSSC technology will have to overcome towards commercialization involve device scale-up and long-term stability. In our group, the fabrication technology of DSSC has been developed from laboratory to module scale over the past few years, nevertheless, the long-term stability has still became a major concern. In this contribution, the long-term DSSC performance in relation to their scale-up from cell to module is investigated. The photoelectrode of the DSSCs were fabricated using nanocrystalline titanium dioxide materials that were subsequently sensitized using ruthenium-based dye. Additionally, TiCl4 pre- and post-treatment were carried out to enhance the overall device efficiency. When fabricated as cells, the DSSC prototypes showed relatively stable performance during repeated tests over three months. In order to increase the output power of the solar cells, the DSSCs were then connected in a Z-type series connection to obtain sub-module panels. The DSSC sub-modules exhibit poor stability, particularly as indicated by the significant decrease in the short circuit current (ISC). Herein, the effect of photoelectrode and sealant materials as well as module design are investigated, highlighting their profound influence upon the DSSC efficiency and long-term stability.

Facile synthesis of Co0.85Se nanotubes/reduced graphene oxide nanocomposite as Pt-free counter electrode with enhanced electrocatalytic performance in dye-sensitized solar cells

A novel nanocomposite of Co0.85Se nanotubes with reduced graphene oxide (Co0.85Se/RGO) is prepared by a facile hydrothermal approach coupled with in situ selenization, which is applied as counter electrode in dye-sensitized solar cells. Electrochemical analysis shows that the Co0.85Se/RGO composite displays a higher electrocatalytic activity for the reduction of triiodide respect to its single components due to the unique hollow structure of Co0.85Se as well as the synergistic effects of high catalytically active Co0.85Se and conductive RGO. As a consequence, the dye-sensitized solar cell (DSSC) fabricated with the Co0.85Se/RGO electrode presents a high photovoltaic conversion efficiency of 7.81%, exceeding the cell based on a Pt electrode (7.55%). Moreover, a considerable electrochemical stability is also achieved when the material was used as a counter electrode in a I−/I3− electrolyte. Therefore, the Co0.85Se/RGO exhibits a huge potential as efficient and low-cost Pt-free counter electrode material to replace Pt allowing for large-scale fabrication of DSSCs.

Engineering of magnetically separable ZnFe2O4@ TiO2 nanofibers for dye-sensitized solar cells and removal of pollutant from water

In this study, magnetic Zinc Ferrite (ZnFe2O4)@TiO2 nanofibers were prepared by low cost and nontoxic route; hydrothermal technique followed by electrospinning process. The prepared magnetic ZnFe2O4@TiO2 nanofibers were morphologically and structurally analyzed by X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), and thermal gravimetric analysis (TGA). The prepared magnetic ZnFe2O4@TiO2 nanofibers were utilized as photoanode for the fabrication of dye-sensitized solar cells (DSSCs) and presented applicable performance with 4.2% overall conversion efficiency with high short circuit current density (JSC) of 10.16 mA/cm2. The maximum ∼42% incident photo-to-current conversion efficiency (IPCE) value was also recorded at 530 nm. In addition, ZnFe2O4@TiO2 nanofibers were not only possessed the good conversion efficiency, but also shown excellent photocatalytic efficiency with magnetic properties towards the dye remediation. Prepared ZnFe2O4@TiO2 nanofibers can be considered as a promising material for energy conversion and environmental applications.

High-Performance Ruthenium Sensitizers Containing Imidazolium Counterions for Efficient Dye Sensitization in Water.

A new type of water-soluble ruthenium sensitizers incorporating imidazolium counterions, denoted [DMPI]2 -Ru and [DMHI]2 -Ru, has been developed, which can be efficiently adsorbed onto TiO2 photoanodes in aqueous solution. Owing to the good thermal stability of imidazolium, [DMPI]2 -Ru adsorbed on TiO2 has a higher decomposition temperature than N719 dye [di(tetrabutylammonium) cis-di(thiocyanato)bis(2,2'-bipyridine-4,4'-dicarboxylato)ruthenium(II)]. When using organic solvent-based I- /I3- electrolytes, solars cell based on [DMPI]2 -Ru-sensitized TiO2 in water show high power conversion efficiencies (PCE) of up to 10.2 %, which is higher than that of N719 (9.9 %) under the common conditions for dye sensitization in organic solvent. [DMHI]2 -Ru, with poorer water solubility than [DMPI]2 -Ru, gives a smaller dye-adsorption amount on TiO2 and thus a lower PCE of 9.4 %. From the viewpoint of safety and environmental impact, the fabrication of dye-sensitized solar cells (DSSCs) by using water as solvent is undoubtedly a preferable strategy. Although the [DMPI]2 -Ru-based device fabricated by using water as the solvent for both the dye-sensitization process and the electrolyte gives a relatively low efficiency, it provides a promising approach for the practical application of DSSCs.

Preparation and Characterization of Zinc Oxide Based Photoanode for Dye-sensitized Solar Cell using Delonix Regia Natural Dye Extract

<p>As of late, research on the fabrication of natural dye-sensitized solar cells has been growing tremendously, largely due to its low cost and environmentally friendly nature. We have fabricated Zinc Oxide (ZnO) based Dye-sensitized Solar Cell (DSSC) using Delonix Regia, locally known as the Gulmohar flower natural dye extract. Zinc Oxide nanostructure films were allowed to grow on Fluorine-doped Tin Oxide (FTO) substrates via hydrothermal process. The seed layer for this was prepared by the spin coating method. The ZnO film’s structure, topology, and optical properties were then studied using X-ray Diffraction (XRD), an Atomic Force Microscope (AFM) and an Ultraviolet Visible (UV-Vis) Spectrophotometer respectively. The X-ray results showed the hexagonal system structure of ZnO oriented along (101) planes. The effect of ethylene glycol on the structural property of ZnO film was also studied. The current voltage curve of DSSC showed the open circuit voltage and short circuit current of 360 mV and 80 μA respectively.</p><p><strong>Journal of Nepal Physical Society</strong><br />Volume 4, Issue 1, February 2017, Page: 1-6</p>

Benzo[1,2,5]thiadiazole dyes: Spectral and electrochemical properties and their relation to the photovoltaic characteristics of the dye-sensitized solar cells

Important aspects of dye-sensitized solar cells (DSSCs) fabrication based on dyes including benzothiadiazole unit were investigated. Two absorption peaks of the dyes covering the 330–551 nm region and possessing moderate band energy gap (1.83–2.16 eV) were found to be important to demonstrate high photovoltaic efficiency (η > 8) in metal free iodide/iodine electrolyte composed DSSCs. Furthermore, the dye energy band gap determined from optical spectra decreases with the increase of DSSCs short circuit photocurrent density, which in turn linearly increases the photovoltaic efficiency of DSSCs. While the RedOx potentials of dyes are less functionally related to the photovoltaic properties of the DSSCs, their appropriate values (0.67 ≤ Eox ≤ 1.1 V and −1.75 ≤ Ered ≤ −0.91 V) can be important for efficient DSSCs. Fabrication details increasing photovoltaic efficiency of the devices based on dyes with benzothiadiazole unit were found. The relationships obtained in the work can be used for preliminary prognosis whether a newly synthesized dye is a promising metal-free sensitizer for DSSCs or not.

Fabrication of Semi-quasi Solid DSSC using Spiro Material as Hole Transport Material

Dye Sensitized Solar Cells (DSSC) has been emerging a promising development in recent years. DSSC is a low-cost solar cell belonging to the third generation of solar cells. However, the conversion efficiency of DSSC is still far behind compared to silicon based solar cells. To produce long stability of DSSC, the used of solid state electrolyte is recommended instead of liquid electrolyte, though solid state DSSC also has problem relating to a lack of pore-filling hole transport material into mesoporous TiO2. In this work an attempt to improve performance of DSSC has been done by adding hole transport material into mesoporous TiO2 layer and optimizing fabrication method. In the first part of the work, we used low Tg material spiro-TAD and spiro-TPD as hole transport material with mosalyte and hybrid polymer as gel electrolyte to obtain a semi-quasi solid DSSC. In the second part, we modified fabrication method by annealing process before spin-coated spiro material into dye-coated TiO2 substrate. Current–voltage measurement of semi-quasi solid DSSC was performed using halogen lamp. We found that the used of spiro-TPD as hole transport give the best power conversion efficiency η = 2.03% of semi-quasi solid DSSC.

Presence of NaI in PEO/PVdF-HFP blend based gel polymer electrolytes for fabrication of dye-sensitized solar cells

Poly(vinylidene fluoride-co-hexafluoro propylene) copolymer (PVdF-HFP) and polyethylene oxide (PEO) blend gel polymer electrolytes (GPEs) containing ethylene carbonate (EC) and propylene carbonate (PC) as solvent with different concentrations of sodium iodide (NaI) salt are prepared. Effect of sodium iodide (NaI) on the gel polymer electrolyte system is investigated by using electrochemical impedance spectroscopy (EIS), temperature-dependence ionic conductivity, X-ray diffraction (XRD) and FTIR studies. The highest ionic conductivity value for the gel polymer electrolytes are 6.38mScm−1 in the presence of 100wt% of sodium iodide (NaI) salt with respect to weight of PEO/PVdF-HFP polymer blend. The temperature-dependent ionic conductivity study indicates that the gel polymer electrolyte system follows the Arrhenius model. Dye-sensitized solar cells (DSSCs) are fabricated using gel polymer electrolytes and tested under Sun simulator. The highest energy conversion efficiency value of 5.67% is obtained after the addition of 100wt% of sodium iodide (NaI) salt.

A scalable monitoring method of dye uptake in dye-sensitized solar cells and modules: Optimization of Z907 impregnation time for long term stability

In the fabrication of dye-sensitized solar cells (DSSC), dye coating is a time-consuming and critical step. Rapid sensitization processes suitable for DSSC industrialization require appropriate dye loading measurement methods. We present a non-destructive method, in which we monitor a fast continuous-flow dyeing process by UV–Vis analysis on the exhaust solution flowing out of the cells. The proposed approach has the advantage over a direct optical analysis on the photo-anode of being independent from film non-uniformity, transparency and area. The monitoring method was successfully applied to evaluate the dependence of Z907 dye adsorption kinetic on temperature, flow rate and dye initial concentration, both on small cells and on 23cm×23cm DSSC modules. Saturation of dye uptake is reached after 40min for 0.3mM dye solution and the rate constant is determined to be 0.114min−1. The results are discussed and correlated with DSSC photovoltaic performances, showing that a longer coloration time has a beneficial influence on long term stability.

Fabrication and characterization of dye-sensitized solar cells based on nanostructured ZnO photoanodes

Fabrication and characterization of dye-sensitized solar cells based on nanostructured ZnO photoanodes

Physicochemical and photo-electrochemical characterization of novel N-doped nanocomposite ZrO2/TiO2 photoanode towards technology of dye-sensitized solar cells

This work introduces the synthesis of N-doped nanocomposite of ZrO2/TiO2 nanofibers (NFs) by use of both electrospinning and hydrothermal methods. The physicochemical properties of the introduced TiO2 NFs are investigated to describe the morphology, crystallinity and chemistry through FESEM, SEM-EDX, XRD, TEM and XPS. As the results, the investigated material can be described as N@ZrO2/TiO2 NFs. The crystal structure of the prepared TiO2 is only anatase structure. Then, the novel NFs are utilized to design novel photoanode and photo-electrochemical characterization such as current-potential response under light, incident photon-to-current efficiency (IPCE) and electrochemical impedance spectroscopy (EIS) of the dye-sensitized solar cell (DSC) are also investigated. The photovoltaic response showed that the efficiency of the DSCs employed N@ZrO2/TiO2 photoanode gave 4.95%, which was higher than those of DSCs designed with ZrO2/TiO2 NFs (4.51%) and N@TiO2 NFs (4.41%) photoanodes. The high photo-response of DSC by use of N@ZrO2/TiO2 NFs can be attributed to enhanced electrical conductivity, which is studied via EIS, and presence of active sites of N. These active sites can easily absorb dye-molecules in the step of dye-loading in the fabrication of DSC.

Fabrication of dye-sensitized solar cells using a both-ends-opened TiO 2 nanotube/nanoparticle hetero-nanostructure

Abstract We fabricated a hetero-structure photoanode with both-ends-opened TiO2 nanotubes and TiO2 nanoparticles for dye-sensitized solar cells (DSSCs). Two-step anodization and selective etching process were used to obtain the both-ends-opened TiO2 nanotubes. A heat treatment was employed to obtain anatase crystal-structured nanotubes. The effect of the both-ends-opened TiO2 nanotubes on the photoelectric conversion efficiency (PCE) of the DSSCs was evaluated by positioning the TiO2 nanotubes on TiO2 nanoparticle layers and by sandwiching them between the TiO2 nanoparticles. It is suggested that both-ends-opened TiO2 nanotubes serve as incident light scattering layers that lead to superior light harvesting efficiency of DSSCs. This increases the electron lifetime and results in the recycling of more light by dye molecules, thus increasing the photocurrent density. Consequently, a high PCE of 7.74% was obtained when the TiO2 nanotubes were placed on the TiO2 nanoparticles and a PCE of 8.56% was obtained when the TiO2 nanotubes were placed between the TiO2 nanoparticles.

CuS thin film grown using the one pot, solution-process method for dye-sensitized solar cell applications

Abstract The counter electrode has a great influence on the performance of dye-sensitized solar cells (DSSCs). In this work, efforts have been made to develop a platinum (Pt)-free, low-cost, copper sulfide (CuS) counter electrode for application in DSSCs. CuS thin film was successfully grown on a conducting and non-conducting substrate using a low temperature, one pot, solution-process method. The as-synthesized CuS thin film was utilized in the DSSCs as a counter electrode (CE). The CE demonstrated good electrocatalytic properties and a photoconversion efficiency (PCE) of 5.03% when used in DSSCs. It was also comparable with devices made using platinum counter electrodes. Synthesized CuS thin film with excellent electrocatalytic properties could serve as an alternative counter electrode in DSSC fabrication.

Investigation on the role of cost effective cathode materials for fabrication of efficient DSSCs with TiNT/TiO2 nanocomposite photoanodes

Free-standing, micrometer long TiO2 nanotube arrays (TiNTs) were synthesized via anodization by utilizing selected transition metals and non-transition elements as cathode materials. Free-standing TiNTs arrays with the maximum tube length up to 153µm was fabricated with Ti cathode material, whereas, the cost effective cathodes materials of charcoal and graphite pencil yielded nearly 100µm long nanotubes for an anodization time of 48h. The barrier layer was removed from the bottom of the free-standing TiNT arrays using chemical etching process. The as-synthesized open ended free-standing amorphous arrays were then crystallized into anatase phase. The annealed free-standing TiNT array was powdered and mixed with TiO2 nanoparticles (NP) to form TiNT/TiO2 NP composite and then utilized as photoanodes to fabricate dye sensitized solar cells (DSSCs). The J-V characteristics and the performances of the solar cells were studied and compared. The results indicate that the TiNT arrays developed with different cathode materials are similar to or in some cases superior to those nanotubes obtained using Pt cathode. Thus, the strategy employed in this work provides a simple, efficient and economical fabrication method for large scale production of TiNT arrays.

Synthesis of organic sulfobetaine‐based polymer gel electrolyte for dye‐sensitized solar cell application

We have synthesized eco‐friendly, economic, and equally efficient polysulfobetaine‐based gel electrolyte to the alternative of liquid electrolyte in the fabrication of dye‐sensitized solar cells (DSSCs) for the first time. This nitrogen‐rich and highly conductive polysulfobetaine was synthesized by an easy and facile method without the use of any catalyst and explored for its DSSC application. The synthesized polymer gel electrolyte exhibited good ionic conductivity about 6.8 × 10−3 Scm−1 at ambient temperatures. DSSCs were fabricated based on this polysulfobetaine gel electrolyte and studied for their performance based on photovoltaic parameters. The DSSC photovoltaic results were appreciable and are Voc = 0.82 V, Jsc = 11.49 mA/cm2, FF = 66%, and PCE = 6.26% at 1 sun intensity. These values are slightly lower than conventional liquid electrolyte‐based DSSC shown as Voc = 0.78 V, Jsc = 12.90 mA/cm2, FF = 69%, and PCE = 7.07%, both at 100 mWcm−2. Conductivity and photovoltaic parameters of the device reveals that as prepared polysulfobetaine‐based polymer gel electrolyte may be useful in the fabrication of DSSC and other electrochemical devices. Copyright © 2017 John Wiley & Sons, Ltd.