Fabrication Of Dye-sensitized Solar Cells Research Articles

Synthesis and Photophysical Characterization of Unsymmetrical Squaraine Dyes for Dye-Sensitized Solar Cells Utilizing Cobalt Electrolytes

Development of novel near-infrared (near-IR) dyes compatible with cobalt complex based redox shuttles for their utilization as sensitizer is inevitable for the fabrication of high-efficiency dye-sensitized solar cells (DSSCs). A series of newly designed unsymmetrical squaraine dyes as a model of near-IR sensitizer were synthesized and characterized for their application as far-red sensitizers of DSSCs utilizing Co(bpy)2+/3+ redox electrolyte. It was shown that logical molecular design led to not only energetic tunability of the sensitizers but also the possibility of good far-red photon harvesting up to 750 nm. One of the newly designed sensitizers, SQ-110, bearing two long alkyl substituents in combination with an electron donating methoxy group directly linked to the aromatic ring was par excellent in terms of its photoconversion efficiency among the dyes utilized in this work. DSSC fabricated using SQ-110 as sensitizer and Co(bpy)2+/3+ redox electrolyte furnished a photoconversion efficiency of 1.98% along with good photon harvesting mainly in the far-red wavelength region. It was further demonstrated that dye molecular structure plays a rather more prominent role than their energetics in controlling the overall device performance of the DSSCs.

Control of Interfacial Properties between Polymer Gel Electrolytes and Counter Electrodes for Efficient Quasi-Solid Photoelectrochemical Solar Cells

There has been much attention towards dye-sensitized solar cells (DSSCs) for the past decades due to their attractive features such as reasonable energy conversion efficiency and low energy production cost. Recently, cobalt complexes have been suggested as one of the most promising candidates for replacing conventional iodine redox shuttles owing to their high voltage characteristics. Although high energy efficiency exceeding 12% was reported by employing liquid electrolyte that consists of cobalt complex redox mediator and volatile solvent, the use of volatile liquid solvent cannot ensure the long-term stability of DSSCs. In this work, therefore, novel polymer gel electrolytes (PGEs) including cobalt complexes as redox couples have been developed for efficient and long-term stable DSSCs. The physicochemical properties of PGEs were adjusted by selecting proper solvent and functional additives (for improving cobalt complex solubility and cation transference number etc.). Polyethers with polar groups (e.g. PEO and PMO) and polymers without polar groups (e.g. PVdF-HFP) were used as the polymer additives for the gelation of the liquid electrolytes with various blending ratios. Especially, various organic solvents with relatively high boiling points were tested to prepare long-term stable polymer gel electrolytes containing cobalt complex redox shuttles. Solvents with high donor number induced significant dissolution of dyes attached on TiO2 and therefore the low volatile solvents with moderate donor number and dielectric constant were utilized in this work. DSSCs employing PGEs with cobalt redox couples also showed better long-term stability compared with those of DSSCs filled with liquid electrolytes at 50 oC for 700 h. In addition, several types of conjugated polymer based counter electrodes have been prepared and used for the fabrication of DSSCs to decrease the high charge transport resistance occurred between the PGE and counter electrode. The photovoltaic and electrochemical performances of the DSSCs have been systematically analyzed via the J-V curve measurement and various electrochemical characterizations such as EIS and CV analyses. Acknowledgments: This work was supported by a grant (No.2017000140002/ RE201702218) from the Environmental Industry Advancement Technology Development Project of Korea Environmental Industry & Technology (KEITI) funded by Korea Ministry of Environment (MOE).

Environmentally friendly dye for dye-sensitized solar cells from roots and stems of Berberis vulgaris

In this research, alkaloid compounds were extracted from the roots and stems of Berberis vulgaris using response surface methodology. The experimental design used absorption intensity as the response at three levels and four factors. The results showed that the factors of mesh and solvent percentage had more meaningful effects than those of temperature and time. Extractions were performed in an incubator shaker with 90% methanol solvent as optimal. The absorption intensity for the roots and stems of the plant was 1.299 and 0.867, respectively. The extracted dye was used in the fabrication of dye-sensitized solar cells. The surface morphology of the samples was studied using atomic force microscopy. Under optimal conditions, low aggregation between the dye molecules and TiO2 film decreased the average surface roughness in comparison with the condition in which the dye molecule concentration increased. The solar cell was built using optical electrodes sensitized with the roots and stems of B. vulgaris, and the calculated solar cell output under optimal conditions was 0.304 and 0.309, respectively. Electrochemical impedance spectroscopy was used to study the internal resistance of the solar cells, and it was shown that an increase in electron transfer between the dye molecule surface and TiO2 film decreased solar cell resistance.

Synthesis of Titanium Dioxide (TiO2) via Sol–Gel Method and Fabrication of Dye-Sensitized Solar Cell

Synthesis of Titanium Dioxide (TiO₂) via Sol–Gel Method and Fabrication of Dye-Sensitized Solar Cell

Conductive regenerated cellulose film as counter electrode for efficient dye-sensitized solar cells

Cellulose-based material for novel and functional application, has attracted more attention, due to its degradable, renewable and green nature. In this research, a conductive regenerated cellulose film (CRCF) was developed as an effective counter electrode (CE) for preparing dye-sensitized solar cells (DSSCs). The CRCF presented desirable surface morphologies and structure and low resistance, and the resultant DSSC showed a high power conversion efficiency of 8.11%, which was comparable to that of traditional platinum-CE DSSC. Our discovery opens a new avenue for promoting cellulose application, as well as fabrication of cost-effective and eco-friendly DSSCs.

Dye-Sensitized Solar Cells Prepared with Mexican Pre-Hispanic Dyes

A dye-sensitized solar cell (DSSC) is a photovoltaic device capable of generating electrical power from the absorption of solar radiation. These cells use a SnO2 : F/TiO2/dye heterojunction as the active electrode (working electrode). Active electrodes containing TiO2 in the anatase crystalline phase and synthetic dyes are used to achieve high conversion efficiencies. Synthetic dyes, whether organic or organometallic compounds, have the disadvantage of being expensive. For this reason, many efforts are made worldwide to find natural dyes with lower production costs that can be used in the fabrication of DSSCs. Nocheztli is a natural red dye obtained from the cochineal insect Dactylopius coccus; the dye dates from pre-Hispanic times and contains high levels of carminic acid (CA). Nocheztli has been used in Mexico in textile dyeing from pre-Hispanic times to the present. Carmine is an organometallic dye with two molecules of carminic acid and one atom of aluminum in its structure; it is obtained by the interaction of the carminic acid from Nocheztli with aluminum salts. Carminic acid and carmine molecules contain a carboxyl group in their structure, allowing them to anchor to TiO2, creating a suitable heterojunction to prepare DSSCs. In this study, both dyes are used to sensitize the mesoporous TiO2m semiconductor to prepare DSSCs.

Interfacial charge transport studies and fabrication of high performance DSSC with ethylene cored unsymmetrical dendrimers as quasi electrolytes

In this paper, authors focus the synthesis of conjugated unsymmetrical stilbenoid dendrimers by Heck and Horner-Wadsworth-Emmons coupling. In UV–visible absorption spectrum, the intensity of the absorption increases with increase in the generation of dendrimers. Further, bathochromic shift is observed on increasing the generation of the dendrimer from zero to first due to the greater widening of the energy gap between π-π* orbitals of the dendrimer system. Interfacial charge transport kinetics such as resistance, chemical capacitance and relaxation lifetime of the fabricated dye-sensitized solar cells (DSSC) are investigated using Nyquist and Bode phase plots by electrochemical impedance spectroscopy. Reduced electron relaxation lifetime (τe) of 1.83 ms (LiI + 7) and 1.04 ms (LiI + 8) provides efficient charge injection and thus reducing recombination process in the device. The performance of DSSC fabricated using unsymmetrical conjugated dendrimers with iodide electrolyte shows higher power conversion efficiency (PCE) than standard LiI based device. Two fold increments are achieved in PCE with first generation unsymmetrical dendrimers compared to their zeroth counterpart. The first generation unsymmetrical dendrimer 8 shows better PCE of 9.037% than all other synthesized dendrimers in the newly fabricated DSSC.

Preparation and characterization of (100 − x) TiO2 + (x)ZnO nanocomposites for dye-sensitized solar cells using Beta vulgaris and Syzygium cumini natural dye extract

The present paper attempts to report the preparation of TiO2–ZnO nanocomposite photoanode materials for dye-sensitized solar cells (DSSC) and analyse the efficiency of DSSC with natural dyes. The structural and optical characteristics of the composites were studied by transmission electron microscopy, X-ray diffraction, field effective scanning electron microscopy, energy dispersive spectrometry, photoluminescence and absorption spectroscopy. The synthesized nanocomposites formed on FTO substrates are applied as photoanode in a dye-sensitized solar cell (DSC). The natural dyes extracted from Beta vulgaris (Beetroot) and Syzygium cumini (black plum) were used in the fabrication of DSSC. The solar cells’ photovoltaic performance in terms of short-circuit current, open circuit voltage, fill factor and energy conversion efficiency was tested with photocurrent density–voltage measurements. The evolution of the solar cells parameters is explored as a function of the photoanode and type of dye used in DSSC fabrication.The obtained results show that the efficiency of DSSC significantly changes with the addition of ZnO to TiO2, while the Beta vulgaris dye has evidently shown higher photo sensitized performance compared to Syzygium cumini in the preparation of DSSC.

Novel High Pressure Exfoliated Graphene-Based Semitransparent Stable DSSCs for Building Integrated Photovoltaics

Integrating dye-sensitized solar cells (DSSCs) with a building’s architecture is required for its commercialization. Coupling semitransparent designer DSSCs with windows has the dual benefit of providing daylighting and power generation. To achieve this, we report a low-cost, novel, high-pressure exfoliation technique for graphene and utilize it as a transparent counter electrode for fabrication of semitransparent DSSCs. By adopting environmentally friendly and economic exfoliated graphene instead of conventional platinum, the overall device cost comes down. The electrocatalytic behavior of fabricated transparent graphene counter electrode was assessed using cyclic voltammetry, Tafel plot in symmetry cell configuration, and impedance spectroscopy. We have fabricated DSSC with >70% transmittance in the visible spectrum, which gives promising power conversion efficiency of 3.19%. The fabricated cells were stable for more than 500 h under constant illumination with no significant efficiency drop. Also, we ha...

Extraction and application of natural pigments for fabrication of green dye-sensitized solar cells

Four dye-sensitized solar cell devices are designed and fabricated based on natural dyes extracted from Celosia Cristata, Saffron, Cynoglossum, and eggplant peel, as photosensitizers. The UV–vis technique has been served to determine maximum absorption of natural extract and pre-dyed photoanode. The Fourier transform infrared (FT-IR) was employed to cover the presence of functional groups. The cyclic voltammetry method has been employed to assess the possibility of charge transfer from dried natural dyes to the photoelectrode. The performance of natural-based dye-sensitized solar cells is determined subsequently. The highest power conversion efficiency was ca. 1.38%, which belonged to Celosia Cristata extract. The devices were examined for higher efficiencies, individually, co-sensitized arrangement and/or in tandem with each other.

Fabrication and Characterization of Dye-Sensitized Solar Cells Based on Flower Shaped ZnO Nanostructures.

Herein, we report a facile synthesis, characterization and dye sensitized solar cell (DSSC) application of flower-shaped ZnO nanostructures. The flower-shaped ZnO nanostructures were synthesized by low-temperature hydrothermal process and characterized in detail by several techniques. The detailed morphological studies confirmed that the flower-shaped structures are formed by the accumulation of several nanoneedles which are axially arranged through their bases in a special fashion that they made flower-like morphologies. The compositional, structural and optical characterizations revealed that the synthesized flowers possess high purity, well-crystallinity with the wurtzite hexagonal phase and good optical properties. The synthesized flower-shaped ZnO nanostructures were used as photoanode to fabricate DSSC which attained a reasonable solar to electrical conversion efficiency of ~1.1%, open-circuit current (VOC) of 0.611 V, short circuit current (JSC) of 3.53 mA/cm2 and fill factor (FF) of 0.51.

Performance of Strelitzia reginae Flowers Dye as Sensitizer for New Dye-Sensitized Solar Cell Fabrication

In current study, the dye from flowers petals of Strelitzia reginae used for the first time to prepare natural photosensitizer for DSSC fabrication. Among five different solvents used to extract the natural dye from S. reginae flowers, the ethanol extract of anthocyanin dye revealed higher absorption spectrum of 0.757a.u. at wavelength of 454nm. A major effect of temperature was studied to increase the extraction yield. The results show that the optimal temperature was 70 °C and there was a sharp decrease of dye concentration from 0.827 at temperature of 70 °C to 0.521 at temperature of 90°C. The extract solution of flowers of S. reginae showed higher concentration in acidic media, especially at pH 4 (0.902). The C, H, N elemental analyses of natural extract showed the presence of N (10.52%), C (18.97%) and H (2.229%) contents. The presence of anthocyanin in the extract of S. reginae and their functional groups were determined using UV-Vis spectroscopy and Fourier-Transform Infrared Spectroscopy (FTIR). The optical properties of deposited TiO2 thin film were studied using scanning electron microscope (SEM) and X-Ray Diffraction (XRD). In Addition, other confirmation that dye supported surface of TiO2, inhibition of crystallinity of TiO2 was investigated by the Energy Disperse X-ray (EDX) analysis. According to experimental results, the conversion efficiency of DSSC fabricated using anthocyanin dye obtained from S. reginae flowers was 0.1%, with short-circuit current (Isc) of 0.6 mA/cm-2, open-circuit voltage (Voc) of 0.51 V and fill factor (FF) of 36.83%.

Direct Comparison of Electron Transport and Recombination Behaviors of Dye-Sensitized Solar Cells Prepared Using Different Sintering Processes

Flexible dye-sensitized solar cells on plastic substrates have achieved a conversion efficiency of 8.6% with the hot compression technique (<150 °C). However, the value of efficiency is only 70% of that achieved using glass substrates with high-temperature sintering technique (500 °C). Investigating the origin of this difference is a critical step for further improving the performance of plastic dye-sensitized solar cells. In this study, an optimized ternary viscous titania paste without the addition of organic binders enables the fabrication of efficient dye-sensitized solar cells with a low-temperature process. Therefore, the electron-transport behavior of dye-sensitized solar cells can be directly compared with those prepared with the high-temperature sintering technique. In addition to the structural and optical differences, the hot compressed photoanode of dye-sensitized solar cells have an electron diffusion coefficient that is 2 times smaller and a recombination time that is 6 times shorter than th...

Highly Conductive and Stable Graphene/PEDOT:PSS Composites As Metal Free Cathodes for Organic Dye-Sensitized Solar Cells

Graphene is a potential candidate as a counter electrode (CE) material to replace the Pt for long-term stability and low-cost fabrication of dye-sensitized solar cells (DSSC). Although the catalytic activity of graphene towards iodine-based redox mediator is not significantly high, it exhibited excellent electrocatalytic activity for cobalt-based redox mediators. However, the low adhesion capacity of graphene with FTO and low stability is the significant problems of graphene based CE for the development of long-term stable DSSCs. This research demonstrated the fabrication of highly stable with strong adhesion capacity based graphene nanoplatelets (GnP) CEs for organic DSSCs. We used conducting polymer (PEDOT:PSS) together with GnPs to improve the adhesion, stability, and catalytic activity. Different weight percent (%) of GnPs were mixed with PEDOT:PSS (PP), and subsequently dispersed by ultrasonication. The dispersed solutions were deposited on FTO by an electro spray (e-spray) method and their electro-catalytic properties were measured for Co(bpy)3 2+/3+ redox couple (bpy=2,2′-bipyridine). The optimal PP/GnP (PPG) CE with 1wt% GnP mixed PP exhibited the profound improvement in conductivity, eletrocatalytic activity, and electrochemical stability for the Co(bpy)3 2+/3+ redox couple compared to the Pt, GnP, and PP CEs. The charge transfer resistance (R CT) of the optimal PPG CE at the CE/electrolyte interface was 0.07 W.cm2, which is much lower than that of Pt CE (1.02 W.cm2). Moreover, the optimal PPG CEs showed better electrochemical stability under prolonged potential cycling. The DSSCs based on the Y123 sensitizer and optimal PPG CE showed a higher photovoltaic performance (J sc, FF, and h of 13.64 mA/cm2, 67.01%, and 8.33%, respectively) than those of Pt-CE (J sc, FF, and h of 13.27 mA/cm2, 65.52%, and 7.99%, respectively), GnP-CE (J sc, FF, and h of 12.74 mA/cm2, 65.69%, and 7.61%, respectively), and PP-CE (J sc, FF, and h of 12.27 mA/cm2, 60.72%, and 7.03%, respectively).

Semi-automatic spray pyrolysis deposition of thin, transparent, titania films as blocking layers for dye-sensitized and perovskite solar cells.

For proper function of the negative electrode of dye-sensitized and perovskite solar cells, the deposition of a nonporous blocking film is required on the surface of F-doped SnO2 (FTO) glass substrates. Such a blocking film can minimise undesirable parasitic processes, for example, the back reaction of photoinjected electrons with the oxidized form of the redox mediator or with the hole-transporting medium can be avoided. In the present work, thin, transparent, blocking TiO2 films are prepared by semi-automatic spray pyrolysis of precursors consisting of titanium diisopropoxide bis(acetylacetonate) as the main component. The variation in the layer thickness of the sprayed films is achieved by varying the number of spray cycles. The parameters investigated in this work were deposition temperature (150, 300 and 450 °C), number of spray cycles (20–200), precursor composition (with/without deliberately added acetylacetone), concentration (0.05 and 0.2 M) and subsequent post-calcination at 500 °C. The photo-electrochemical properties were evaluated in aqueous electrolyte solution under UV irradiation. The blocking properties were tested by cyclic voltammetry with a model redox probe with a simple one-electron-transfer reaction. Semi-automatic spraying resulted in the formation of transparent, homogeneous, TiO2 films, and the technique allows for easy upscaling to large electrode areas. The deposition temperature of 450 °C was necessary for the fabrication of highly photoactive TiO2 films. The blocking properties of the as-deposited TiO2 films (at 450 °C) were impaired by post-calcination at 500 °C, but this problem could be addressed by increasing the number of spray cycles. The modification of the precursor by adding acetylacetone resulted in the fabrication of TiO2 films exhibiting perfect blocking properties that were not influenced by post-calcination. These results will surely find use in the fabrication of large-scale dye-sensitized and perovskite solar cells.

NiS/rGO nanohybrid: An excellent counter electrode for dye sensitized solar cell

We report the synthesis of a novel nanohybrid based on nickel sulfide (NiS) nanoparticles decorated reduced graphene oxide (rGO) following a facile hydrothermal approach for application as Pt-free counter electrode (CE) in dye sensitized solar cells (DSSC). The DSSC devices fabricated using this NiS/rGO nanohybrid film as CE showed an impressive power conversion efficiency (PCE) of 9.5% and a fill factor of about 0.78 when illuminated by AM 1.5 G simulated solar light. These values are well above those reported previously for DSSCs fabricated with Pt free CE and thus establishes the potential of the NiS/rGO nanohybrid as an excellent low-cost CE material for DSSC fabrication. The improvement in the PCE is due to improved electro-catalytic activity of the NiS/rGO nanohybrid for reduction of the triiodide caused by the synergistic effects of highly catalytic NiS nanoparticles and electrically conductive rGO.

Fabrication of dye-sensitized solar cell using chlorophylls pigment from sargassum

Dye-sensitized solar cell (DSSC) is a new generation of the solar cell. Its development in the dye-sensitized system is varied. Natural dyes have been the choice in developing DSSC. This study used a dye-sensitized chlorophyll pigment from Sargassum sp. as a dye-sensitized solar cell. This study aims to obtain chlorophyll pigment extract to be used as a dye in DSSC and to obtain the best energy conversion efficiency from DSSC. The chlorophyll pigments were extracted using APHA method (2012), and the TiO2 coating method used was doctor blade method. The two fabricated cells have an area of 1 cm2 immersed with chlorophyll dye for 30 hours. Then these cells were tested using direct sun radiation. The concentration value of chlorophyll in acetone solution was 61.176 mg/L. The efficiency value obtained was 1.50% with VOC of 241 mV, ISC 2.9 x 10-4 mA and fill factor 0.432.

PEMBUATAN SEL SURYA TERSENSITASI PEWARNA (SSTP) LAPISAN TiO2/GRAFIT DARI EKSTRAK KELOPAK BUNGA ROSELLA, BERAS KETAN HITAM, DAN UBI JALAR UNGU

Fabrication of Dye-Sensitized Solar Cells (DSSC) using working electrodes composed of a mixture of TiO2 and 14% of graphite, which then denoted as TiO2:C14%, has been done. The TiO2:C14% colloid was deposited on a conductive Fluorine Doped Tin Oxide (FTO) glass substrate by using sol-gel-spin coating at the speed of 1500 rpm for 50 seconds. This thin layer was then immersed for 24 hours in different dye solutions extracted from Rosella petals (hibiscus sabdariffa), black glutinous rice (oryza sativa) and purple sweet potato (ipomoea batatas). Composition materials used to fabricate the solar cells were characterized by using x-ray diffraction (XRD) and scanning electron microscope (SEM). The power conversion efficiency (PCE) of the solar cells was measured by using a set of I-V characteristic circuit. The result showed that the highest PCE of 3 x 10-3 % was obtained from the cells based on dye extracted from rosella petals compared to those from black glutinous rice and purple sweet potato.&#x0D; &#x0D; Keywords: DSSC, dye, rosella, TiO2, spin coating, XRD, efficiency.

Effect of composition of chlorophyll and ruthenium dyes mixture (hybrid) on the dye-sensitized solar cell performance

The fabrication of dye-sensitized solar cell (DSSC) has been conducted by varying the composition of natural dye from moss chlorophyll (Bryophyte) and synthesis dye from ruthenium complex N719. The sandwich structure of DSSC consists of the working electrode using TiO2, dye, electrolyte, and counter electrode using carbon. The composition of chlorophyll and synthesis dyes mixture were 100% and 0%, 80% and 20%, 60% and 40%, 40% and 60%, and 20% and 80%. The UV-Vis absorption spectra of moss chlorophyll showed the first peak in the wavelength range of 450-500 nm and the second peak at wavelength of 650-700 nm. The peak value of absorbance at wavelengths of 450-500 nm was 6.1004 and at wavelengths of 650-700 nm was 3.5835. The IPCE characteristic curves showed the absorption peak of photon for DSSCs occurred at wavelength of 550-650 nm. It considered that photon in this wavelength can contribute dominantly to produce the optimum electrons. The I-V characteristics of DSSCs with composition of chlorophyll and synthesis dyes mixture of 100% and 0%, 80% and 20%, 60% and 40%, 40% and 60%, and 20% and 80% resulted the efficiency of 0.0022; 0.0194; 0.0239; 0.0342; and 0.0414, respectively. It suggested that the addition of a little composition of the ruthenium complex dye into moss chlorophyll dye can increase the efficiency significantly.

Synthesis and characterisation of SnO2 nanostructures for Dye-Sensitized Solar Cells

Tin Oxide (SnO2) is a wide band gap n-type semiconducting material having good chemical stability, electrical and optical properties. SnO2 nanostructures were prepared by surfactant assisted solvothermal technique at different pH conditions and used as n-type layer for Dye-Sensitized Solar Cell (DSSC) fabrication. Herein we report the characterization of SnO2 nanostructures by various techniques like Fourier-transform Infra Red spectroscopy (FT-IR), Ultra – Violet and Visible Spectroscopy (UV-Vis), Photoluminescence (PL), Powder X-Ray diffraction (XRD) and Scanning Electron Microscopy (SEM). SnO2 prepared at pH – 8 and 10 were used for the fabrication of DSSC and the efficiency was relatively higher at pH 8.