Counter Electrode For Dye-sensitized Solar Cells Research Articles

Recent Advances on Pt-Free Electro-Catalysts for Dye-Sensitized Solar Cells.

Since Prof. Grätzel and co-workers achieved breakthrough progress on dye-sensitized solar cells (DSSCs) in 1991, DSSCs have been extensively investigated and wildly developed as a potential renewable power source in the last two decades due to their low cost, low energy-intensive processing, and high roll-to-roll compatibility. During this period, the highest efficiency recorded for DSSC under ideal solar light (AM 1.5G, 100 mW cm−2) has increased from ~7% to ~14.3%. For the practical use of solar cells, the performance of photovoltaic devices in several conditions with weak light irradiation (e.g., indoor) or various light incident angles are also an important item. Accordingly, DSSCs exhibit high competitiveness in solar cell markets because their performances are less affected by the light intensity and are less sensitive to the light incident angle. However, the most used catalyst in the counter electrode (CE) of a typical DSSC is platinum (Pt), which is an expensive noble metal and is rare on earth. To further reduce the cost of the fabrication of DSSCs on the industrial scale, it is better to develop Pt-free electro-catalysts for the CEs of DSSCs, such as transition metallic compounds, conducting polymers, carbonaceous materials, and their composites. In this article, we will provide a short review on the Pt-free electro-catalyst CEs of DSSCs with superior cell compared to Pt CEs; additionally, those selected reports were published within the past 5 years.

Ni2+ enriched carbon nanotubes nanohybrids based non-platinum counter electrodes for dye sensitized solar cells

The development of competent substitutes for Pt counter electrode (CE), possessing excellent electrocatalytic activity, stability, and ready availability, is a key issue to materialize the long-term stability and economical large-scale industrial production of future generation dye sensitized solar cells (DSSCs). In the present work, a cost effective and solution processable hydrothermal technique has been utilized to synthesize Ni2+ enriched nanohybrids of nickel oxide (NiO) and nickel sulfide (Ni3S2) nanoparticles with multi-walled carbon nanotubes (MWCNTs) as CE in DSSCs. NiO/MWCNTs nanohybrids showed superior electrocatalytic behaviour among MWCNTs, NiO, Ni3S2, nanohybrids, and Pt. The nanohybrids containing aligned network MWCNTs exhibited good electrical conductivity, high specific surface area and better stability. These nanohybrids have been further employed as CE in DSSCs and observed higher Power Conversion Efficiency (PCE) for NiO/MWCNTs nanohybrids CE (3.80%) among others and is almost comparable to that of Pt based DSSC (3.90%). It has been explained on the basis of Ni2+content present in the nanohybrids. The higher content of Ni2+species provides a greater number of active sites representing higher electrocatalytic activity that would further productively catalyze the reactions occurring at CE/electrolyte interface in DSSCs.

Enhanced properties of low-cost carbon black-graphite counter electrode in DSSC by incorporating binders

Carbon-based counter electrodes of dye-sensitized solar cells (DSSCs) such as carbon black-graphite composite (CB/Gr) have received unprecedented interest in recent years due to their ease of fabrication, good corrosion resistance, and low cost compared to platinum (Pt) electrodes. However, the poor surface adherence between the carbon counter electrodes (CE) and FTO substrate, low surface area, and poor inter-particle connection between the carbon materials have consistently become a major challenge. In order to overcome these issues, we have fabricated CB/Gr by incorporating binders of titanium (IV) isopropoxide (TTIP), and zirconium (IV) dioxide (ZrO2) as the counter electrodes for the DSSC. The performance of the CE is characterized by four-point probe conductivity measurement, scanning electron microscopy (SEM) and energy dispersive X-ray (EDX), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), and current density voltage (J-V) characteristics. The results revealed that incorporating binders to the CB/Gr has improved the series resistance (RS) and charge transfer resistance (RCT), which enhances the short-circuit current density (JSC), fill factor (FF), and the power conversion efficiency (PCE) of the device. The TTIP binder in CB/Gr CE exhibited superior performance in DSSC is largely attributed to the formation of TiO2 in situ with small particle size of about 100 nm, leading to enhanced intimate contact between the carbon materials, high surface area, and better surface adherence between counter electrode and the FTO substrate. Our findings, thereby, offer the possibility to engineer and optimize the energy levels of CE in an effort to develop a high-performing DSSC counter electrode.

Sb2S3 entrenched MWCNT composite as a low-cost Pt-free counter electrode for dye-sensitized solar cell and a viewpoint for a photo-powered energy system

The current research interest is to use Sb2S3 entrenched Multi-Walled Carbon Nanotubes (MWCNT) composite as Pt-free counter electrode in dye-sensitized solar cells (DSSCs) and also to test its usage as a supercapacitor. Hence here, Sb2S3 nanorods with different concentrations of MWCNT have been synthesized by facile microwave irradiation technique and are used as a counter electrode in Pt-free DSSCs and also tested for supercapacitance. Crystalline structure, shape, and quantum states have been elucidated using XRD, TEM, and XPS spectra, respectively. Among all, Sb2S3/CNT30 composite counter electrode delivers the highest Power Conversion Efficiency (PCE) of 5.02% with a short circuit current (JSC) of 12.68 mA cm−2 and open-circuit voltage (VOC) of 0.68 V. The improvement observed is due to the lower peak-to-peak separation (Epp), higher exchange current density (J0) and lower charge transfer resistance (RCT). The obtained PCE is compared with the standard Pt-based counter electrode (PCE~5.8%) and discussed. This composite is also found to be a suitable material for the supercapacitor. Among the electrodes, Sb2S3/CNT100 exhibits the highest specific capacity of 228 C g−1 with 1 Ag−1 with the capacitive retention of ~92.5% over 1000 charge-discharge cycles, which also reveals its ability for energy storage. The excellent capacitive and photovoltaic output highlights the promise of Sb2S3/MWCNT for photo-supercapacitor devices.

Nickel foam supported Pt as highly flexible counter electrode of dye-sensitized solar cells

In this paper, Pt nanoparticles are deposited on nickel foam by the mild displacement reaction occurring at room temperature. Thus prepared nickel foam supported Pt is used as efficient and highly flexible counter electrode of dye-sensitized solar cells (DSSCs), the performance of which can be enhanced by simply prolonging the reaction time. The results denote that when the reaction time is just 40 min, the nickel foam supported Pt has exhibited better catalytic activities than the commonly used polyethylene naphthalate polymers supported Pt. The deposition of Pt is investigated by the scanning electron microscopy, X-ray photoelectron spectroscopy, energy dispersive spectroscopy and UV–Vis spectra, and the catalytic activities of fabricated flexible Pt counter electrode are verified by electrochemical impedance spectra and cyclic voltammetry curves. The approach proposed here is facile and can be used for the large scale fabrication of efficient flexible counter electrode in DSSCs.

Cobalt and Carbon Complex as Counter Electrodes in Dye-Sensitized Solar Cells

We developed cobalt and carbon complex materials as counter electrodes (CEs) for dye-sensitized solar cells (DSSCs) to replace conventional platinum (Pt) CEs. Co12 and Co15, both of which are basic cobalt derivatives, showed good redox potential with a suitable open-circuit voltage (VOC); however, their poor electrical conductivity engendered a low short-circuit current (JSC) and fill factor (FF). Mixing them with carbon black (CB) improved the electrical conductivity of the CE; in particular, JSC and FF were considerably improved. Further improvement was achieved by combining cobalt derivatives and CB through thermal sintering to produce a novel CoCB material as a CE. CoCB had good electrical conductivity and electrocatalytic capability, and this further enhanced both JSC and VOC. The optimized device exhibited a power conversion efficiency (PCE) of 7.44%, which was higher than the value of 7.16% for a device with a conventional Pt CE. The conductivity of CoCB could be further increased by mixing it with PEDOT:PSS, a conducting polymer. The device’s JSC increased to 18.65 mA/cm2, which was considerably higher than the value of 14.24 mA/cm2 for the device with Pt CEs. The results demonstrate the potential of the cobalt and carbon complex as a CE for DSSCs.

Metal Chalcogenides (MxEy; E = S, Se, and Te) as Counter Electrodes for Dye–Sensitized Solar Cells: An Overview and Guidelines

The dye‐sensitized solar cell (DSSC), a third‐generation photovoltaic technology, has gained considerable attention since the achievement of around 7% efficiency in 1991. To reduce the cost of the commonly used platinum (Pt) counter electrode (CE), different materials with good electrocatalytic activities have been applied as CEs for DSSCs. Recently, transition metal chalcogenides, such as metal sulfides, metal selenides, and metal tellurides, have been investigated because of their low cost, unique electrocatalytic performance, and electronic structure similar to Pt. However, more efforts remain to be made on the mechanism and application of these metal chalcogenides as CEs for DSSCs. Herein, an overview and guidelines are given on recent advances in binary and multinary metal chalcogenides used as CEs in DSSCs. The synthesis techniques and the effect of morphology optimization and stoichiometric ratios are briefly described. The development of composites made of metal chalcogenides combined with highly electrocatalytic materials, especially carbon‐based materials, is also briefly discussed. Some suggestions and methods to improve the power conversion efficiencies (PCEs) of DSSCs designed with metal chalcogenides as CEs are also provided.

An integrated approach to construct tantalum derivatives for electrocatalysis beyond the triiodide reduction reaction

The counter electrode (CE) is an essential component in dye-sensitized solar cells (DSSCs) to transfer electrons and catalyze triiodide reduction. In this research, efficient and cost-effective tantalum derivatives (oxide, nitride, carbide, oxynitride, and corresponding hybrids) are synthesized and utilized as CEs in DSSCs toward the triiodide reduction. The DSSC with mixed-anionic TaON CE achieves a cell efficiency of 5.46%, surpassing that with pristine TaOx CE (5.20%) before nitriding treatment. Benefiting from the synergistic interaction between mesoporous carbon (MC) and TaC0.95, TaC0.95/MC hybrid CE-based DSSC possess superior cell efficiency of 7.23%, higher than that of respective TaC (6.24%) and MC (6.52%), especially standard Pt (6.34%). Furthermore, TaON and TaC0.95/MC CEs exhibit durably great catalytic activity for I3- reduction. This work raises an effective and generally accepted approach to construct transition metal derivatives, which could utilize as low-priced Pt-free electrocatalysts for new energy devices.

Graphene Nanoplatelets–Nickel Nanoparticles Hybrid Counter Electrodes for Low-Cost and Efficient Dye-Sensitized Solar Cells

Reducing the cost of dye-sensitized solar cells (DSSCs) by replacing the expensive platinum (Pt) counter electrode (CE) with low-cost and earth-abundant materials without sacrificing their power conversion efficiency (PCE) is a topic of high interest. Herein, we prepared graphene nanoplatelets/nickel nanoparticles (GnPs/NiNPs) hybrid as a CE for DSSCs by electrochemical deposition of NiNPs onto fluorine-doped tin oxide (FTO) followed by spin coating of GnPs onto NiNPs/FTO electrodes. The optimal GnPs/NiNPs-CE with homogeneously distributed NiNPs with well-defined crystallinity exhibited excellent catalytic activity toward the I−/I3 − redox mediator with low charge transfer resistance at the electrode∣electrolyte interface. The DSSCs with an optimized GnPs/NiNPs-CE electrode exhibited a substantial improvement in efficiency to 7.24%, which is similar to the PCE of the cells with Pt-CE (ca. 7.99%). The GnPs/NiNPs-CE is a promising replacement for the expensive Pt used in DSSCs.

A DFT study on electrocatalytic performance of 12CaO·7Al2O3 (C12A7) with electrolytic LiI applied in DSSCs

The electrocatalytic properties of C12A7 materials were improved by hydrated, protonated, and hydroxylated interactions. Geometric structures, charge transfers, thermodynamic quantities and electronic density of states of the studied reactions were performed using DFT calculations. Based on these calculations, a hydroxylation reaction on C12A7 shows more interesting structures because of its configuration’s shape. According to the band gap, the hydroxylated–C12A7 form is a candidate electrocatalytic material for electrolysis reactions. In this investigation, improved C12A7 with hydroxylation was utilized as an electrocatalytic material for redox reactions with LiI and applied as a counter electrode in dye-sensitized solar cells (DSSCs). The calculated results reveal that the hydroxylated–C12A7 structure can undergo electrocatalytic reactions in DSSC counter electrodes. The result may be useful for further design and experimental improvement of an electrocatalytic mechanism to enhance their electrode properties.

On the Use of PEDOT as a Catalytic Counter Electrode Material in Dye-Sensitized Solar Cells

Dye-sensitized solar cells (DSSCs) emerged in the early 1990s as a promising alternative to the classic silicon-based solar cell due to their unique combination of low cost, ease of fabrication, color palette for building integration, and high efficiency in indoor applications. This review article describes the fabrication and the properties of poly (3,4-ethylenedioxythiophene) (PEDOT)-based catalytic counter electrodes (CEs) for DSSCs. In particular, the electrochemical reactivity PEDOT CEs used in conjunction with alternative redox mediators for DSSCs is outlined. Among alternative redox shuttles, cobalt and copper complexes, as well as totally organic thiolate/disulfide, have been considered. Finally, PEDOT can also be used as a hole conductor material in electrolyte-free solid-state dye-sensitized solar cells. This review clearly shows that the progress in DSSCs development is strongly linked to the introduction of PEDOT as a new counter electrode material.

Nanocomposites of Multi-walled Carbon Nanotubes and Titanium dioxide (MWCNTs/TiO2) as affective counter electrode materials for Platinum-free Dye-Sensitized Solar Cells (DSSCs)

Platinum is commonly used as a catalyst to regenerate the redox mediator in Dye-Sensitized Solar Cells (DSSCs). This work intends to replace the expensive and rare platinum with conventional and economical materials. Nanocomposites of Multi-walled Carbon Nanotubes (MWCNTs) and TiO2 can be used as active catalyst materials for the counter-electrode of DSSC. In these composites, MWCNTs provide catalytic properties, and TiO2 acts as a binder. The interaction between MWCNTs and TiO2 has been investigated by Transmission Electron Microscopy (TEM). It has been observed that DSSCs photovoltaic performance significantly depends on the concentration of MWCNTs in nanocomposites. The amount of MWCNTs has been optimized for the best performance of DSSC. The solar cell assembled with 4%MWCNTs catalyst material showed an efficiency of 8.81%, comparable to Pt-based device (9.40%), fabricated under analogous environment.

Graphene wrapped NiSe2 nanocomposite-based counter electrode for dye-sensitized solar cells (DSSCs)

Strengthening electrical conductivity of metal combine with carbon based content is benefit for improving activity of photovoltaic system. Herein, we designed a NiSe2/graphene hybrid, constructed by NiSe2 nanocrystals homogeneously anchored on the graphene nanosheets, is fabricated through a facile one-step hydrothermal method. The crystallographic, morphology, optical and textural properties of samples were analyzed by XRD, SEM, TEM, UV, PL and BET analysis. The fabricated NiSe2/graphene applied as a counter electrode (CE) of dye-sensitized solar cells (DSSCs) for the first time, which displays remarkable catalytic activity in the reduction of I3−. The DSSC with a NiSe2/graphene CE produces higher power conversion efficiency (10.6%) than bare NiSe2 CE (6.04%) under the same conditions. Hence, NiSe2/graphene products have great potential applications as the CE of DSSCs and can be an efficient method to substitute for Pt in DSSCs.

MoS2/ZIF-8 derived nitrogen doped carbon (NC)-PEDOT: PSS as optically transparent counter electrode for dye-sensitized solar cells

A few-layered MoS2 successfully grown on the nitrogen-doped carbon (NC) derived from zeolitic imidazolate framework (ZIF-8) via the hydrothermal method. A small portions of the obtained MoS2/NC composite blended with Poly (3, 4-ethylenedioxythiophene poly styrene sulfonic acid)PEDOT: PSS(as a conductive binder and utlized as counter electrode (CE) for dye-sensitized solar cells (DSSCs). The spin-coated MoS2/NC-PEDOT: PSS composite on Fluorine-doped Tin Oxide (FTO) glass not only possesses promissing catalytic ability toward the I3-/I-and [Co(bpy)3]2+/3+ redox mediators but also displayed considerable optical transparency in the visible range thus used to fabricate bi-facial DSSCs. The assembled bi-facial devices with MoS2/NC-PEDOT: PSS composite CEs showed an excellent power conversion efficiency (PCE) under both the front and the rear irradiations. The PCE of the device with 5% MoS2/NC-PEDOT: PSS composite CE and I3-/I- redox couple are 7.67 and 4.54%, under the front and rear irradiation respectively. Also, the values of the device with the same composite CE and [Co(bpy)3]2+/3+ redox mediator are 7.87 and 5.34% under the front and rear irradiation, respectively. The optimum performance of the devices with the prepared CEs and both redox systems are comparable with Pt-based devices. Thus, the MoS2/NC-PEDOT: PSS composite CEs are recommend being a promising Pt-free CEs for DSSCs.

Recent Advancement in Photo-Anode, Dye and Counter Cathode in Dye-Sensitized Solar Cell: A Review

Photovoltaic cells are devices that directly convert sunlight into electricity and it is very simple method to utilize the solar energy. Development of low-cost and high-efficiency solar cell is necessary for the large-scale adaption of solar energy. O’Regan and Gratzel in 1991, developed a new cell called Dye Sensitized Solar Cell (DSSC). Inexpensiveness and easy fabrication technique make DSSC an attractive one. An attempt has been made to review the basic components of Dye Sensitized Solar Cell, which influences the performance of the system. Specific inferences by the researchers around the globe obtained using various photo anodes, dyes and counter electrodes in DSSCs have been thoroughly examined, and the optimum material for a pronounced performance is highlighted. Also, different metals and nanomaterials encapsulated photo anodes and counter electrodes are considered for the review and presented.

Chemically synthesized Bi2S3, CuS and Bi2S3/CuS heterostructure materials as counter electrode: Dye sensitized solar cell application

In the present work, we have successfully synthesized Bi2S3, CuS, and its heterojunction Bi2S3/CuS thin film on fluorine doped tin oxide (FTO) coated glass as counter electrodes. These depositions are done by simple, cost effective, and simply executable sequential chemical bath deposition (S-CBD) method. Well optimized preparative parameters led to the formation of good quality thin films of Bi2S3 and CuS films and heterojunction. The structural validation Bi2S3, CuS, and its heterojunction were achieved by X-ray diffraction and Raman scattering, surface morphological study observed through Scanning Electron Microscopy (SEM) and topology was confirmed by Atomic Force Microscopy (AFM). We have employed Bi2S3/CuS heterostructure as a counter electrode (CE) in dye-sensitized solar cell (DSSC). We have observed different parameters like short circuit current density (Jsc), open circuit voltage (Voc), Fill Factor (FF) and efficiency (n) by Current–voltage (J-V) characteristics. Though we do not achieve an anticipated outcome for heterostructure compared with conventional Platinum and Carbon black counter electrode, CuS separately found worthy as Counter electrode (CE) in DSSC.

Engineering MoSe2/WS2 Hybrids to Replace the Scarce Platinum Electrode for Hydrogen Evolution Reactions and Dye-Sensitized Solar Cells.

In recent times, two-dimensional transition-metal dichalcogenides (TMDs) have become extremely attractive and proficient electrodes for dye-sensitized solar cells (DSSCs) and water electrolysis hydrogen evolution as alternatives to the scarce metal platinum (Pt). The active TMD molybdenum selenide (MoSe2) and tungsten disulfide (WS2) are inspiring systems owing to their abundance of active sulfur and selenium sites, but their outputs are lacking due to their inactive basal planes and ineffective transport behavior. In this work, van der Waals interrelated MoSe2/WS2 hybrid structures were constructed on conducting glass substrates by chemicophysical methodologies. For the first time, the constructed MoSe2/WS2 structures were effectively used as a counter electrode for DSSCs and an active electrode for hydrogen evolution to replace the nonabundant Pt. The assembled DSSCs using the designed MoSe2/WS2 heterostructure counter electrode provided a superior power-conversion efficiency of 9.92% and a photocurrent density of 23.10 mA·cm-2, unmatchable by most of the TMD-based structures. The MoSe2/WS2 heterostructure displayed excellent electrocatalytic hydrogen evolution behavior with a 75 mV overpotential to drive a 10 mA·cm-2 current density, a 60 mV·dec-1 Tafel slope, and an over 20 h durable process in an acidic medium. The results demonstrated the advantages of the MoSe2/WS2 hybrid development for generating interfacial transport and active facet distribution and enriching the electrocatalytic activity for DSSCs and the water-splitting hydrogen evolution process.

In situ solvothermal growth of Cu2ZnSnS4 thin film for counter electrode of dye-sensitized solar cells

Quaternary Cu2ZnSnS4 (CZTS) nanocrystalline thin films were in situ grown on FTO coated conductive glass by a low cost solvothermal method. The effect of the reaction time and the concentration of precursor solution on the purity and morphologies of the deposited thin films was studied. The morphology, crystal structure and composition of the deposited thin films were characterized by scanning electron microscope, high resolution transmission electron microscope, X-ray diffraction, Raman spectroscopy and energy-dispersive X-ray spectroscopy. The pure wurtzite CZTS nanoparticles can be formed as the reaction time is 20 h. The film prepared at the optimized precursor solution concentration has uniform thickness, smooth surface and tight binding between the nanoparticles. The performance of the deposited CZTS thin films used as the counter electrode for dye-sensitized solar cells (DSSCs) was evaluated by measuring photocurrent density-voltage curves of DSSCs, electrochemical impedance spectroscopies and Tafel polarization curves of the symmetric cells. Photoelectric conversion efficiency of DSSC based on the optimized CZTS counter electrode reached 6.19%. The excellent photoelectric performance is attributed to the better surface morphology and conductive skeleton of the prepared CZTS thin film. The in situ solvothermal preparation method of the CZTS thin films for counter electrode of DSSCs is green, low cost and simple.

Investigating the Performance of Carbon Black/Tin Selenide Composite As the Counter Electrode in Dye Sensitized Solar Cells

The counter electrode (CE) is an essential component of dye sensitized solar cells (DSSC). Currently, platinum (Pt) is the most widely used CE in DSSCs but it is an expensive material and new lower cost materials are required to replace Pt. In this study, we prepare different carbon black/tin selenide composite CEs using a facile hydrothermal method and employ them in TiO2-based DSSCs. It is shown that the low-cost composite CEs demonstrate very promising electrocatalytic and charge transport properties, and a carbon black/SnSe CE with the weight ratio of 80% can achieve an open circuit voltage of 660 mV and short circuit current density of 12.4 mA/cm3 with a fill factor of 62% which gives an efficiency of 5% that is comparable to that of Pt DSSCs. The results of this paper are confirmed via XRD, FESEM, EDS, cyclic voltammetry, J-V measurement and IPCE analyses.

NickelPalladium alloy–reduced graphene oxide as counter electrode for dye-sensitized solar cells

In this work, nickel-palladium (NiPd) alloy-reduced graphene oxide (rGO) has been prepared via liquid-phase deposition (LPD) technique and applied as counter electrode (CE) of dye-sensitized solar cell (DSSC). The effect of Ni content on the properties of the sample and the performance of the device utilizing the CE has been investigated. The morphology of the sample is described by rumples and white strips distributed on the ITO surface. The device utilizing the CE prepared with the Ni:Pd ratio of 20:1 owns the highest power conversion efficiency (η) of 2.13%. This is due to this device possesses the lowest series resistance (Rs) of 84.6 Ω and the highest incident photon conversion efficiency (IPCE) of 11.30%. The findings of this work reveal that NiPd-rGO has potential to substitute platinum (Pt) as CE of DSSC since its η is comparable to that of Pt based device.