Electrolytes For Dye-sensitized Solar Cells Research Articles

Electrospun membrane of PVA and functionalized agarose with polymeric ionic liquid and conductive carbon for efficient dye sensitized solar cell

Environmentally benign biopolymer nanofibrous membrane was fabricated and applied as a quasi-solid state (QSS) electrolyte in dye-sensitized solar cell (DSSC). In this study, electrospun (PVA/PA/PIL/C) nanofibrous membrane was tailored from phthaloyl agarose (PA), poly(3-butyl-1-vinyl imidazolium iodide) (PIL) along with conductive carbon (C) incorporated in poly(vinyl alcohol) (PVA). The morphology, structure and physical properties (electrolyte uptake, porosity) of the membranes were analysed and their photovoltaic and electrochemical effects as electrolyte in DSSC device were studied. The best QSS-DSSC with PVA/PA/PIL/C membrane exhibited good short circuit current density (Jsc = 13.1 mA/cm2), high open circuit voltage (Voc = 0.79 V), comparable power conversion efficiency (η = 6.05%) and greater stability (up to 82% of its initial conversion efficiency after 500 h). This membrane based electrolyte enunciates the great outlook for the advancement of stable and efficient DSSCs.

Polydopamine-Modified Electrospun Polyvinylidene Fluoride Nanofiber Based Flexible Polymer Gel Electrolyte for Highly Stable Dye-Sensitized Solar Cells.

To overcome the drawbacks of solvent evaporation and leakage from the liquid electrolyte in dye-sensitized solar cells (DSSCs), a polymer gel electrolyte (PGE), based on polydopamine (PDA)-modified electrospun polyvinylidene fluoride (PVDF) nanofibers, PDA@PVDF, was prepared and applied in quasi-solid DSSCs (QS-DSSCs). The PDA coating increased the wettability of the liquid electrolyte by improving the distribution of the ionic liquid electrolyte. This, in turn, enhanced the ion conductivity of the PGE as well as the stability of QS-DSSC. The PDA@PVDF nanofiber membrane exhibited a satisfactory ultimate tensile strength of 9.3 MPa with a failure elongation of 130%. Such high toughness provided excellent mechanical support for the PGE. Owing to the unique pore connected structure of nonwoven nanofibers as well as the reduced surface tension with the liquid electrolytes, the PGE-based QS-DSSC retained 95.7% of the short circuit current from the liquid-electrolyte-based DSSC and showed an energy conversion efficiency of 8.26%. No significant impacts were observed for the open-circuit voltage and fill factor. More importantly, the QS-DSSCs using PDA@PVDF-based PGE showed a significantly improved solar cell stability under both indoor and outdoor conditions.

Effect of the potassium iodide in tetrapropyl ammonium iodide-polyvinyl alcohol based gel polymer electrolyte for dye-sensitized solar cells

Low ionic conductivity in gel polymer electrolytes with large cations is undoubtedly a critical issue. This research’s main objective was to explore potassium iodide influences on the conductivity in gel polymer electrolytes. PVA-based gel polymer electrolytes (GPEs), including tetrapropyl ammonium iodide and potassium iodide have been prepared. The GPEs have been characterized by X-ray diffraction (XRD) and electrical impedance spectroscopy (EIS). The GPEs prepared haves been recognized as an amorphous region through the X-ray diffraction analysis. The GPE sample’s conductivity (100 wt% of tetrapropyl ammonium iodide) of 6.24 × 10−3 S cm−1 was the lowest. The existence of potassium iodide in the GPE system improves the conductivity. The conductivity of 9.72 × 10−3 S cm−1 of GPE containing 30 wt% of tetrapropyl ammonium iodide and 70 wt% of potassium iodide was the highest derived from the EIS analysis. All prepared GPEs have the potential to be used for dye-sensitized solar cell applications. The dye-sensitized solar cell efficiency has been improved by ~30% if potassium iodide exists in the GPE system.

Effects of concentrated light on the performance and stability of a quasi-solid electrolyte in dye-sensitized solar cells

In this study, a quasi-solid dye-sensitized solar cell (QSDSSC) and a liquid DSSC were coupled with a concentric mirror. Under focused concentrated light, the QSDSSC exhibited higher performance stability when compared to the liquid DSSC, which showed remarkably low stability due to the leakage and evaporation of the liquid electrolyte. The QSDSSC retains ~91.4% of its initial efficiency after 120 mins, while the liquid DSSC retains only ~73.2%. The enhanced stability of the QSDSSC is attributed to the 3D frame formed by the nanofillers and polymers, which effectively prevent evaporation and leakage of the electrolyte.

Evaluation of canonical choline chloride based deep eutectic solvents as dye-sensitized solar cell electrolytes.

Deep eutectic solvents (DESs) are beginning to attract interest as electrolyte alternatives to conventional organic solvents and ionic liquids within dye-sensitized solar cells (DSSCs). The precise roles played by DES components and whether they simply represent a benign medium for mobilizing charge carriers or present beneficial functionality that impacts device performance remain unclear. To begin to address this deficiency in understanding, we performed a comprehensive characterization of the three "canonical" choline chloride-based DESs (i.e., reline, ethaline, and glyceline) as DSSC electrolytes hosting the iodide-triiodide (I-/I3 -) redox couple. The measurement of electrolyte viscosities, determination of triiodide diffusion coefficients, and photovoltaic performances assessed for water contents up to 40 wt. % allow the emergence of several important insights. A comparison to the observed photovoltaic performance arising from the individual components aids in further clarifying the impact of DES chemistry and solution viscosity on photovoltaic and charge carrier diffusion characteristics. Finally, we introduce the DES guaniline-consisting of a 1:1 molar ratio mixture of choline chloride with guanidinium thiocyanate-demonstrating it to be a superior DSSC electrolyte over those formulated from the three most widely studied canonical DESs at all water contents investigated.

Investigation of the Long-Term Stability of Different Polymers and Their Blends with PEO to Produce Gel Polymer Electrolytes for Non-Toxic Dye-Sensitized Solar Cells

The electrolyte for dye-sensitized solar cells (DSSCs) is subject of constant innovation, as the problems of leakage and drying greatly reduce the long-term stability of a device. One possible way to solve these problems is the use of gel polymer electrolytes (GPEs) with a gelling structure, which offer different advantages based on the used polymers. Here, potential GPE systems based on dimethyl sulfoxide (DMSO) as solvent for low-cost, non-toxic and environmentally friendly DSSCs were investigated comparatively. In order to observe a potential improvement in long-term stability, the efficiencies of DSSCs with different GPEs, consisting of polyacrylonitrile (PAN), acrylonitrile-butadiene-styrene (ABS), polyvinyl alcohol (PVA) and poly (vinylidene fluoride) (PVDF) and their blends with poly (ethylene oxide) (PEO), were investigated over a period of 120 days. The results indicate that blending the polymers with PEO achieves better results concerning long-term stability and overall efficiency. Especially the mixtures with PAN and PVDF show only slight signs of deterioration after 120 days of measurement.

High-efficiency quasi-solid state dye-sensitized solar cells using a polymer blend electrolyte with “polymer-in-salt” conduction characteristics

“Polymer-in-salt” electrolytes are special conductive materials that demonstrate much higher conductivity compared to the conventional “salt-in-polymer” electrolytes. However, up-to-now, they are found unsuitable for dye-sensitized solar cells (DSSCs) application, mainly because they lead to increased charge recombination rate. The present paper demonstrates the development and application in DSSCs of polymer blend electrolytes that utilize features found in “polymer-in-salt” electrolytes, while the aforementioned drawback is overcome. This is done with the appropriate selection and amount of polymers used to jellify the liquid state electrolyte, keeping the redox couple concentration fixed at a high level. Herein, the unique properties of polyvinylpyrrolidone (PVP), as a nitrogen-containing heterocyclic polymer, in combination with the ability of polyethylene glycol (PEG) to dissolve high quantities of ionic compounds, were the main reasons for developing PVP/PEG blend-based polymer electrolytes for DSSCs. The efficiency attained by the solar cells employing the polymer blend electrolytes was found enhanced up to 30% compared to the corresponding of DSSCs employing the PVP-based and PEG-based polymer electrolytes. By the extra use of two common additives in the best-performing polymer blend electrolyte and an advanced multi-layered photo-anode, the efficiency of DSSCs reached 8.21%, which is one of the highest reported for quasi-solid state DSSCs employing non-composite ionic liquid-free iodide-based polymer electrolytes. The results are also found quite satisfactory compared to the corresponding ones obtained by the DSSCs employing commercially available liquid state electrolytes, while the preparation of the proposed electrolytes is simple and of low-cost, and their composition has great prospects for further improvement.

Eco-Friendly Dye-Sensitized Solar Cells Based on Water-Electrolytes and Chlorophyll

Organic solvents used for electrolytes of dye-sensitized solar cells (DSSCs) are generally not only toxic and explosive but also prone to leakage due to volatility and low surface tension. The representative dyes of DSSCs are ruthenium-complex molecules, which are expensive and require a complicated synthesis process. In this paper, the eco-friendly DSSCs were presented based on water-based electrolytes and a commercially available organic dye. The effect of aging time after the device fabrication and the electrolyte composition on the photovoltaic performance of the eco-friendly DSSCs were investigated. Plasma treatment of TiO2 was adopted to improve the dye adsorption as well as the wettability of the water-based electrolytes on TiO2. It turned out that the plasma treatment was an effective way of improving the photovoltaic performance of the eco-friendly DSSCs by increasing the efficiency by 3.4 times. For more eco-friendly DSSCs, the organic-synthetic dye was replaced by chlorophyll extracted from spinach. With the plasma treatment, the efficiency of the eco-friendly DSSCs based on water-electrolytes and chlorophyll was comparable to those of the previously reported chlorophyll-based DSSCs with non-aqueous electrolytes.

High-voltage solar energy conversion based on ZIF-67-derived binary redox-quasi-solid-state electrolyte

Abstract Zeolitic imidazolate framework-67 (ZIF-67) nanoparticles were incorporated into a traditional redox quasi-solid-state nanogel polymer electrolyte system to form a color-tunable and energy-efficient binary redox-quasi-solid-state electrolyte for dye-sensitized solar cells. The operation of the traditional redox quasi-solid-state nanogel polymer electrolyte system is based on the I–/I3– redox couple reaction with an I2 intermediate. However, this system has issues, such as solvent leakage, low voltage, and color limitation, because the iodide-based components are in a relatively fluidic state. For addressing the durability issue, we employed ZIF-67 nanoparticles to form a quasi-solid-state electrolyte. Additionally, the ZIF-67 nanoparticles were partially decomposed into cobalt ions, which provided an additional Co2+/Co3+ redox couple system for operating the electrolyte system with the binary redox shuttle. The ZIF-67 nanoparticles reduced the polymer chain crystallinity, increasing the ion conductivity. In contrast, the tetrahedral coordinated cobalt ions in the framework, and dissociated cobalt ions absorbed visible light, leading to a loss of electron excitation. Thus, the current density decreased slightly. Nevertheless, the Co2+/Co3+ redox couple provided a modified electron level for the binary redox couple system, significantly enhancing the open-circuit voltage. Regarding practical significance, with tuning of the binary redox system, the binary redox-quasi-solid-state electrolyte can potentially exhibit color-tunable characteristics. Thus, the method of incorporating coordinated porous nanomaterials to form the binary redox-quasi-solid-state electrolyte can be adapted to other transparent renewable energy devices for increasing the operating voltage and enhancing the stability.

Improved performance and long-term stability of organogelator electrolyte based semi-solid-state dye sensitized solar cells with electrospun ZnO-TiO2 hybrid films

Abstract The liquid electrolytes for dye-sensitized solar cells (DSSCs) have been identified as one of main obstacles for commercialization. One possible way to resolve this problem is to employ the semi-solid electrolyte. In this respect, we apply two types of electrolytes, namely liquid and low molecular weight organic gelator (LMOG) to fabricate the semi-solid state DSSCs and investigate their effects over the efficiency and long-standing thermal stability of devices. Unlike the conventional TiO2 nanoparticulate films, we have introduce a hybrid oxide layer consisting of nanocomposites of TiO2 nanospheres (NSPs) mingled with ZnO nanofibers (NFs) namely (mixed ZnO NFs + TiO2 NSPs) produced by a novel electrospray technique. This route resulted in an effective contact between the electrolyte and the highly porous layer of dye-coated hybrid film as the gel electrolyte penetrated within the pores. The semi-solid state DSSCs fabricated using hybrid oxide films for the LMGO based electrolyte exhibits power conversion efficiency (PCE) of 9.51%, which is considerably greater compared to cells based on TiO2 nanoparticulate films (5.14%). The semi-solid state DSSCs using the LMOG-based gel electrolyte demonstrate the significantly improved device performance and stability compared to the devices using the liquid electrolyte owing to their enhanced light trapping which serves as a scattering layer. Remarkably, the champion devices based on gel electrolyte produce the maximum PCE of 10.69%, the highest efficiency reported so far for these types of devices.

Organosoluble, esterified starch as quasi-solid biopolymer electrolyte in dye-sensitized solar cell

Fabrication of quasi-solid state polymer electrolytes are recently being endorsed by electrochemists due to its superior electrical and physical properties. With the aspiration to develop a sustainable electrolyte component, this study is a novel attempt to fabricate quasi-solid electrolyte based on esterified starch. Potato starch was chemically modified via simple phthaloylation method. The resulting amorphous, hydrophobic starch derivative was used as a polymer base to prepare cost effective thermoplastic gel electrolytes via incorporation of propylene carbonate, dimethylformamide and lithium iodide. Fourier transform infrared spectroscopy and X-ray diffraction characterizations verified the impact of phthaloylation and plasticization in suppressing the crystallinity and hydrophilicity of starch. The biopolymer gel with 40 wt.% LiI recorded the highest room temperature ionic conductivity of 4.82 mS cm−1. The sample with highest ionic conductivity recorded the best efficiency of 3.56%, which is one of the highest values for starch electrolyte-based dye-sensitized solar cells (DSSC). The optimized efficiency indicate that starch-based electrolyte has good prospects for fabrication of quasi-solid DSSC.

Consolidation of ion promoters into quasi solid-state (QSS) polymer electrolytes for dye-sensitized solar cells (DSSCs)

Enhanced quasi solid-state (QSS) polymer electrolytes were developed by consolidating dissolved polyacrylonitrile (PAN) in a binary organic solvent of ethylene carbonate-propylene carbonate (EC-PC) with ion promoters such as 1-methyl-3-propylimidazolium iodide (MPII), sodium iodide (NaI) salt, and Iodine (I2). In this work, the concentration of I2 was varied to one-twentieth, one-fifteenth, one-tenth, one-fifth, and equal of the total weight of the NaI salt used. The purpose of this study is to investigate the dependence of dye-sensitized solar cells (DSSCs) performance on the concentration of I2. Fourier-transform infrared (FTIR) spectroscopy study confirmed that there is a complexation occurred between all materials used. The electrolyte consists of I2 with one-tenth of the weight of the NaI salt (I1/10 electrolyte) has achieved the highest ionic conductivity of 8.70 × 10–3 S cm-1 at ambient temperature. From the current density-voltage (J-V) study, DSSC based I1/10 electrolyte has achieved the best photovoltaic efficiency of 6.47%.

P(HEMA-co-EA) as host polymer for flexible dye-sensitized solar cell (DSSC) electrolyte

An electrolyte is the main component of a dye-sensitized solar cell (DSSC) which influences the efficiency of the DSSC. In order to prevent leakage problem and adhesive problem, new solid-state polymer electrolyte proposed rather than using a liquid electrolyte. For this research, new copolymers using 2-hydroxyethyl methacrylate (HEMA) and Ethyl Acrylate (EA) monomers are randomly copolymerized via UV-cure polymerization method with different ratio of each monomer (10,30,50,70,90) towards development as a solid-state electrolyte in flexible DSSC. In this study, the best ratio of the copolymer HEMA-co-EA will be the host polymer for electrolyte in DSSC. The most promising characteristics as a host in polymer electrolytes are due to its smooth cross-sectional surface and lowest glass transition temperature. Therefore, a best ratio of p(HEMA-co-EA) will be stirred with sodium iodide (NaI), Tetrahydro folic acid (THF) and iodine crystal for 24 hours to form a homogenous solution of an electrolyte. This p(HEMA-co-EA) will incorporate with different weight ratios of sodium iodide (NaI). This research reported that after 1500 s only three ratios of new host polymer p(HEMA-co-EA) were successfully copolymerized completely. All three ratio will be characterized by physical appearance, FTIR, DSC and XRD. By naked eyes, only 3 ratios of monomer (50HEMA:50EA, 70HEMA:30EA and 90HEMA:10EA) gave brittle structure which proved the copolymerization process completely success. For FTIR, those three ratios show the breakdown of a double bond at the HEMA monomer structure proved the complete copolymerization process. DSC shows that all three ratio shows the glass transition temperature (Tg) and only 50HEMA:50EA gave melting temperature (Tm) at 192.49°C and XRD confirmed the phase structure and crystallinity of three ratios. All these characterizations show that HEMA and EA monomers can be successfully random copolymerize with a three suitable ratio of each monomer and been used as an electrolyte for flexible DSSC.

Synthesis and characterization of poly-3-(9H-carbazol-9-yl)propylmethacrylate as a gel electrolyte for dye-sensitized solar cell applications

Poly-3-(9H-carbazol-9-yl)propylmethacrylate (pCMA) is synthesized as a polymer gel electrolyte and employed in the fabrication of dye-sensitized solar cells (DSSC). The pCMA was characterized by various analytical techniques to examine its structural and thermal properties. The photovoltaic and electrochemical effects of this electrolyte in DSSCs were investigated. From the results, it was found that DSSCs assembled with pCMA-PGE is an efficient electrolyte, which yields an open-circuit voltage 545 mV and current density 10 mA for a cell of area 0.25 cm2. pCMA-PGE device shows better performance (η = 2.2%), and it also performs as a good host polymer matrix for redox couple in the electrolyte.

Choline chloride-based deep eutectic solvents as effective electrolytes for dye-sensitized solar cells

Electrolytes for dye-sensitized solar cells remain a challenge for large-scale production and commercialization, hindering the wide application of solar cells. We have developed two new electrolyte-based deep eutectic solvents using a mixture of choline chloride with urea and with ethylene glycol for dye-sensitized solar cells. The prominent features of the two deep eutectic solvent electrolytes are simple preparation for large-scale production with inexpensive, available, and nontoxic starting materials and biodegradability. The solar cell devices proceeded in a safe manner as the two deep eutectic solvents afforded low-cost technology and comparative conversion efficiency to a popular ionic liquid, namely 1-ethyl-3-methylimidazolium tetracyanoborate. Results showed that devices with choline chloride and urea electrolyte exhibited improved open circuit voltage values (VOC), while the ones with choline chloride and ethylene glycol showed an increase in the short circuit current (Isc). Characterization of the devices by electrochemical impedance spectroscopy helped explain the effects of their molecular structures on the enhancement of either VOC or Isc values. These new solvents expand the electrolyte choices for designing dye-sensitized solar cells, especially for the purpose of using low-cost and eco-friendly materials for massive production.

The development of poly(ethylene oxide) reinforced with a nanocellulose-based nanocomposite polymer electrolyte in dye-sensitized solar cells

Here, we describe a nanocomposite polymer electrolyte prepared using a solution casting technique.

Cu(ii/i) redox couples: potential alternatives to traditional electrolytes for dye-sensitized solar cells

DSSCs have reached certified efficiency of 11.9% and device efficiency of 14.3% using I−/I3− or Co(ii/iii) redox shuttles. But, they have many constraints and Cu(i/ii) electrolytes are found to be best alternatives and the efficiency has crossed 30% under low light conditions, potential applications in Internet of things.

Biopolymer-Based Electrolytes for Dye-Sensitized Solar Cells: A Critical Review

Continual escalation of our world population demands a vast and safe energy supply, the majority of which has been produced by fossil fuel sources. However, because of the huge energy demand, expon...

Effect of polyaniline (PANI) on efficiency enhancement of dye-sensitized solar cells fabricated with poly(ethylene oxide)-based gel polymer electrolytes

Ionically conducting gel polymer electrolytes can be used effectively to improve the problems associated with liquid electrolytes in dye-sensitized solar cells (DSSCs) and in particular to reduce their electrode degradation. In this work, gel polymer electrolytes containing poly(ethylene oxide) (PEO), LiI, and I2 were used as the redox electrolyte and conducting polymer; polyaniline (PANI) as an additive was introduced to the PEO-based electrolytes. The effect of incorporating PANI into the PEO-based gel electrolyte on iodide ion conductivity and solar cell performance was studied. The gel polymer electrolyte without PANI showed a conductivity of 1.23 × 10−3 S cm−1 at room temperature, while the electrolyte incorporating 1.5 wt% PANI showed an enhancement in conductivity increasing its value up to 1.87 × 10−3 S cm−1. While the DSSCs fabricated without PANI in the electrolyte showed 5.00% efficiency, the DSSCs fabricated with 1.5 wt% PANI-incorporated polymer electrolyte showed 6.56% efficiency under the same illumination of 100 mW cm−2(AM 1.5) simulated sunlight. Ionic conductivity and FTIR results suggest that the increase in electrolyte conductivity and the enhancement of DSSC performance appear to be due to the combined result of the plasticizing effect on decreasing the crystallinity of the PEO polymer and the improved ionic dissociation due to “trapping” and immobilizing the Li+ cations in the polymer matrix by PANI, creating more iodide (I−) ions in the redox medium.

Development of Rapid Curing SiO2 Aerogel Composite-Based Quasi-Solid-State Dye-Sensitized Solar Cells through Screen-Printing Technology.

Grätzel's dye-sensitized solar cells (DSSCs) can readily convert sunlight into electricity, attracting considerable attention of global scientists. The fabrication efficiency of DSSCs was greatly limited by the slow fabrication (∼3.5-24 h) of quasi-solid (QS) electrolytes to date. In this study, novel composites of SiO2 aerogel with graphene (GR), multi-walled carbon nanotubes, or polyaniline were proposed in the fabrication of QS-state electrolytes. The morphology of these composites was characterized. The gels with SiO2 aerogels as QS electrolytes of DSSCs can be rapidly cured in ∼3 s. Using the screen-printing technology, these QS electrolytes can be readily utilized to construct the QS-DSSC to provide high efficiency and great stability. The photovoltaic parameters and interfacial charge-transfer resistances of the QS-DSSC incorporated with our synthetic composites were investigated in detail. Specifically, the SiO2 aerogel composed of GR (SiO2@GR) as a gel can greatly improve the performance of QS-DSSCs up to 8.25%. It is likely that these SiO2 aerogel composite electrolytes could provide a rapid curing process in the preparation of QS-state DSSCs, which might be useful to promote the development of DSSCs for future industrialization.