Quasi-solid State Dye-sensitized Solar Cells Research Articles

Gellan gum/PEDOT:PSS gel electrolyte and application on quasi-solid dye sensitized solar cells

GG/PEDOT:PSS (Gellan gum/poly(3,4-ethylenedioxythiophene) polystyrene sulfonate) based gel electrolytes were prepared and characterized via FESEM, EDS, XRD, Raman, FTIR, and thermogravimetric analysis. In addition, these hydrogels were immersed in I-/I3- based liquid electrolytes and used as gel electrolytes for Quasi-solid-state Dye Sensitized Solar Cells (QS-DSSC). QS-DSSCs that used prepared hydrogel electrolytes were characterized with Linear Sweep Voltammetry and Electrochemical Impedance Spectroscopy for obtaining important photoelectrochemical parameters such as VOC, JSC, FF, light conversion efficiency (η), and charge transfer properties within the cell. Also, in this study, the thickness effect of hydrogel electrolytes was investigated. It was observed that with increased thickness, efficiency decreased because of the recombination reactions. 2.01% efficiency was obtained for QS-DSSCs with thin-layered gel electrolyte.

Effective redox shuttles for polymer gel electrolytes-based quasi-solid-state dye-sensitized solar cells in outdoor and indoor applications: Comprehensive comparison and guidelines

Various redox shuttle-mediated polymer gel electrolytes (PGEs) were utilized individually to fabricate quasi-solid-state (QSS) dye-sensitized solar cells (DSSCs) for outdoor and indoor applications. The power conversion efficiency (PCE) of QSS DSSCs based on I3−/I−-mediated PGEs was comparable with liquid electrolyte-devices under both 1-sun and 1000 lux compact fluorescent light (CFL) (compact fluorescent lamp) illuminations. The PCEs for QSS-DSSCs based on cobalt/copper complex-mediated PGEs were not comparable with their liquid electrolyte DSSCs under 1-sun condition, but, comparable, even higher for cobalt complex-mediated PGE devices, under CFL light. The PCE for organic dye-sensitized cobalt PGE devices was in the range of 23%–30% under 200–2000 lux CFL illuminations. The remarkable PCEs of 27.5% and 25.0% were obtained for cobalt and copper complex-mediated PGE-based QSS DSSCs using organic sensitizers, respectively, under 1000 lux CFL light. This result specifies that the mass transport limitation of Co-/Cu-complexes in PGEs can only be applicable for 1-sun illumination, not for ambient lighting. The outstanding efficiency under CFL ambient light and high stability under 50 °C make us optimistic for future commercial utilization of metal-complex-mediated PGE-QSS DSSCs as a safe power source for the internet of things and low-powered autonomous electronic devices.

Synthesis of polymer-gel electrolytes for quasi solid-state dye-sensitized solar cells and Modules: A potential photovoltaic technology for powering internet of things (IoTs) applications

Dye-sensitized solar cells can display brilliant performance in artificial/indoor light, predominantly in various wireless sensor networks applications. The main objective of this work was to fabricate stable dye-sensitized solar cells/modules for the internet of things applications. The stability issue was addressed by developing polymer gel electrolytes. Polymer gel electrolyte with the highest ionic conductivity value was then employed as an electron transport mediator in the cells and modules. The photovoltaic performance of cells was affected by the conductivity of electrolytes. The results showed that the efficiency of quasi-solid state dye-sensitized solar cells remained stable for a week, while the efficiency of conventional cells approached zero after a day. Thus, the development of polymer gel electrolytes is an ultimate solution to enhance the stability of dye-sensitized solar cells and modules for the internet of things applications.

Development of quasi solid state dye sensitized solar cells

Dye Sensitized Solar Cells (DSSCs) present a significant renewable energy source in terms of control of different parameters governing flexibility, efficiency, lifetime and cost. The liquid electrolytes used inside the cells are generally responsible for the leakage and inefficient encapsulation related issues. These are critical for practical applications of DSSCs. The choice of electrolyte medium used in the cell should take into account the fast regeneration of electrolyte and redox potential of the dye. Organic dyes in general, exhibit better extinction coefficients and variant color ranges. The present work is focused on quasi solid state DSSCs based on an organic dye. For the fabrication of devices, nanocrystalline titanium-di-oxide (TiO2) films were used as the photoanode and well known organic dye Eosin B as the sensitizer. The photovoltaic performance of the cells was measured at different light intensities. The results exhibited the quantum efficiency of organic dye Eosin B which can be used as a potential sensitizer in conjugation with quasi solid state electrolytes. Copyright © 2017 VBRI Press.

Au-doped mesoporous SiO2 scattering layer enhances light harvesting in quasi Solid-State dye-sensitized solar cells

This study investigates the morphological effect of different Au-doped SiO2 scattering layers on the performance of dye-sensitized solar cells (DSSCs). Particularly, the SiO2 sources were varied to yield different geometries, i.e., tetraethyl orthosilicate (TEOS) templated SiO2, Sidoarjo mud (LuSi) extracted SiO2, and commercial silica glass sphere. The microstructure, as well as physical, electronic, and optical properties of different Au-doped SiO2 particles, were characterized using SEM-EDX, TEM, BET, XRD, and various spectroscopy techniques. The photoelectrochemical performance of quasi-solid state DSSCs was indicated by current density–voltage (J-V) response, external quantum efficiency spectra, and the impedance response. The results indicate that the performance of TiO2-based DSSCs is enhanced quite significantly due to the improved photocurrent generation and fill factor. The short circuit current density is found up to 370% higher (and hence, the conversion efficiency) than the reference cell upon incorporating Au-doped crystalline SiO2 extracted from LuSi (Voc = 0.89 V, Jsc = 1.28 mA‧cm−2, FF = 0.65, and η = 0.75%). This substantial photocurrent enhancement stems from the combined effect of efficient light scattering by submicron SiO2 particles, surface plasmon resonance, and reduced interfacial recombination by SiO2 insulation. In addition, the optimum size of SiO2 particles is deduced as the results indicate the size-scattering dependency which controls the gain and loss of photocurrent due to the type of scattering.

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.

Highly efficient gel electrolytes by end group modified PEG-based ABA triblock copolymers for quasi-solid-state dye-sensitized solar cells

To get highly efficient quasi-solid-state dye-sensitized solar cells (QSS-DSSCs) with long-term stability using polymer gel electrolytes (PGEs), well-defined ABA triblock copolymers ([Poly(methyl methacrylate)]2-block-poly(ethylene glycol)) with different end functionality and components of I-/I3- liquid electrolytes (LEs) are studied and optimized for the fabrication of PGE-based QSS-DSSCs. Triblock copolymers are synthesized in a one-step reaction using bifunctional PEG-macro chain transfer agent (MCTA) by reversible addition-fragmentation chain transfer (RAFT) polymerization. Due to the high reactivity and toxicity of sulfur-containing trithiocarbonate end groups, ABA triblock copolymers prepared from RAFT polymerization are further modified to sulfur-free 2-methylpropionitrile and 4-cyanopentanoic acid end functional triblock copolymers by radical-induced exchange reactions. Dodecyl trithiocarbonate end functional PEG-MCTA and triblock copolymers absorb UV-light in the region of 260–380 nm, whereas sulfur-free carboxylic acid and 2-methylpropionitrile end functional polymers do not absorb in that UV-light region. Among three different end functional polymers, the carboxylic acid end functional triblock copolymer has the highest thermal stability. Based on electrochemical parameters, photovoltaic performance, and long-term stability, 1,2-dimethyl-3-propylimidazolium iodide (DMPII) ionic liquid and 4-tert-butylpyridine (TBP) additive containing acetonitrile-based I-/I3- LEs are effective for PGEs. The highest power conversion efficiency (PCE) for QSS-DSSCs achieved under simulated 1-sun illumination is up to 10.34%, which is comparable with the highest PCE of 10.39% for LE-DSSCs. Considering the high reactivity, thermal stability, UV-absorption, and the toxicity of the trithiocarbonate end group, the SGT-643-C triblock copolymer with carboxylic acid end group can be a promising candidate as a sulfur-free polymeric matrix for gel electrolytes of QSS-DSSCs.

A novel multifunctional polymer ionic liquid as an additive in iodide electrolyte combined with silver mirror coating counter electrodes for quasi-solid-state dye-sensitized solar cells

A novel multifunctional polymer ionic liquid poly(oxyethylene)-imide-2,2,6,6-tetramethyl-1-piperidinyloxy (POEI-TEMPO) was successfully prepared and used as an additive in iodide electrolyte in quasi-solid-state dye-sensitized solar cells (QSS-DSSCs).

PAN-Based Triblock Copolymers Tailor-Made by Reversible Addition–Fragmentation Chain Transfer Polymerization for High-Performance Quasi-Solid State Dye-Sensitized Solar Cells

For efficient polymer gel electrolytes (PGEs) in quasi-solid-state dye-sensitized solar cells (QSS-DSSCs), six ABA triblock copolymers based on (poly(acrylonitrile-co-N-(isobutoxymethyl)acrylamide)-block-poly(ethylene glycol)-poly(acrylonitrile-co-N-(isobuto-xymethyl)acrylamide)) (P(AN-co-BMAAm)-b-PEG-b-P(AN-co-BMAAm)) with various copolymer compositions and molecular weights, coded as SGT-605, SGT-606, SGT-608, SGT-609, SGT-611, and SGT-612, have been synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization using PEG-functionalized macro-RAFT agents. The effects of copolymer compositions and molecular weights in P(AN-co-BMAAm)-b-PEG-b-P(AN-co-BMAAm) triblock copolymers were investigated in terms of electrochemical properties and photovoltaic performance as PGEs. The ionic conductivity was increased with N-(isobutoxymethyl)acrylamide (BMAAm) composition of these triblock copolymers, which is attributed to the availability of free iodide ions by complex formation among acrylamide groups with Li+ ions. However, polymer gel electrolytes with high molecular weights enhance ionic conductivity due to the lower amount of polymers required for the gel formation. Thus, the photovoltaic performances of PGE-based QSS-DSSCs improved along with the increase in the molecular weight of the triblock copolymer. The addition of 7 wt % TiO2 nanofiller into PGEs produced a higher ionic conductivity and diffusion of I3– than the corresponding PGEs. The resulting power conversion efficiency (PCE) of QSS-DSSCs using SGT-612/TiO2 composite PGEs under simulated 1-sun condition was 9.83% (Voc, 792.8 mV; Jsc, 16.65 mA/cm2; FF, 74.52%), which was higher than that of liquid electrolyte DSSCs (PCE 9.53%; Voc, 743.8 mV; Jsc, 17.16 mA/cm2; FF, 74.64%). The long-term device stability of PGE-based QSS-DSSCs was better than the liquid-state DSSCs.

Covalently functionalized graphene oxide with cobalt–nitrogen-enriched complex containing iodide ligand as charge carrier nanofiller for eco-friendly high performance ionic liquid-based dye-sensitized solar cell

For the first time, a new class of heterocyclic conjugated cobalt complex with specially designed iodide ligand onto functionalized nitrogen-enriched graphene oxide sheets (Co-complex-NGO) was synthesized as efficient charge transferable nanofiller (NF), which promoted the photovoltaic performance of quasi-solid-state dye-sensitized solar cell (QS-DSSC). This NF is unique with active sites of heterocyclic Co-complex-NGO that can generate redox-active spices on the GO surface. The ionic liquid electrolyte consisted of highly dispersed hydrophilic Co-complex-NGO NF has more than 86% wider electrochemical window and a 64% lower charge transfer resistance compared to the bare ionic liquid-based electrolyte. Cells utilizing an optimized amount 0.75 wt% NFs indicated power conversion efficiency (η) of 7.287, showing 70.37% enhancement compared to the cells using a referenced electrolyte (4.277%). Such excellent η correlates with the induced formation of a π-π interaction-shielding model between aromatic systems in the electrolyte which effectively improves the open-circuit voltage and the short-circuit current density. Given the superior long-term stability of the optimized device and excellent photoelectric conversion efficiency of the promoted ionic liquid-based electrolyte, this research will open up a new way to overcome the drawbacks of volatile-liquid electrolytes.

Quasi-solid-state composite electrolytes with Al2O3 and ZnO nanofillers for dye-sensitized solar cells

In the literature, so far, in-situ chemical cross-linking methods have been utilized for the preparation of Al2O3 or ZnO-composite polymer gel electrolytes (PGEs). Such PGEs have shown poor performance in quasi-solid-state dye-sensitized solar cells (QS-DSSCs) under one-sun conditions. Moreover, the QS-DSSCs using ZnO-PGEs had higher open-circuit voltages (Voc) than the cell using Al2O3-PGEs; but their conversion efficiencies are much lower. To solve this problem, for the first time, composite printable electrolytes (CPEs) are fabricated by dispersion Al2O3 and ZnO nanofillers (NFs) in the quasi-solid-state electrolytes. The electrochemical properties of the CPEs and their effects on the QS-DSSCs performance are systematically studied and compared. The results show that the diffusion coefficients of ions in Al2O3CPEs are much higher than in ZnOCPEs. However, the introduction of ZnO NFs significantly decreases the charge recombination at the photoelectrode/electrolyte interface than do by the Al2O3. Therefore, the QS-DSSCs using Al2O3CPE and ZnOCPE have, respectively, higher current density and higher Voc; and the highest efficiencies achieved are 8.73% and 7.59%. These efficiencies are significantly higher than those reported for the QS-DSSC PGEs using the two NFs. The mechanisms of the two NFs are proposed by analysis the iodide ions on the two NFs using X-ray photoelectron spectroscopy and ultraviolet-visible spectroscopy.

Multi-layers of TiO2 nanoparticles in the photoelectrode and binary iodides in the gel polymer electrolyte based on poly(ethylene oxide) to improve quasi solid-state dye-sensitized solar cells

A gel electrolyte based on poly(ethylene oxide) is optimized in order to improve dye-sensitized solar cells (DSCs) by varying the contents of a binary mixture of salts, LiI, and Hex4NI (tetrahexylammonium iodide). Two series of electrolytes, one excluding and the other including 1-butyl-3-methylimidazolium iodide (BMII) and 4-tert-butylpyridine (4TBP), are investigated. The added BMII and 4TBP improve the conductivity in electrolytes. The highest conductivities at all the measured temperatures are shown by the electrolyte which includes BMII and 4TBP along with the Hex4NI:LiI molar ratio of 3:2. This composition in gel polymer electrolyte exhibits relatively high ionic conductivities, 4.44 × 10−3 and 6.93 × 10−3 S cm−1 at 25 and 50 °C, respectively. Quadruple-layered and highly porous nanocrystalline photoelectrodes that are prepared by spin coating TiO2 nanoparticles of the size 13 and 21 nm were used for the DSC preparation. DSCs that are assembled with BMII and 4TBP added electrolytes exhibit higher efficiencies. The DSC fabricated using the electrolyte having performance enhancers along with Hex4NI:LiI molar ratio of 2:3 and the photoelectrode having quadruple layers of TiO2 nanoparticles exhibit the highest short-circuit current density (11.1 mA cm−2), open-circuit voltage (770 mV), and efficiency (5.58%). The stability of the DSC performances is monitored by measuring current-voltage as a function of time. The cell optimized in this study exhibits a good short-term stability. The positive effects of TiO2 nanoparticle multilayers in the photoelectrodes, as well as of binary salt and performance enhancers in the electrolyte, are successfully utilized to enhance the performance of DSCs.

Polymer Gel Electrolytes Based on PEG-Functionalized ABA Triblock Copolymers for Quasi-Solid-State Dye-Sensitized Solar Cells: Molecular Engineering and Key Factors.

The molecular weights and structural properties of polymers play key roles in the efficiency of gelators in polymer gel electrolytes (PGEs) for quasi-solid-state dye-sensitized solar cells (QSS-DSSCs). To find an appropriate gelator, we synthesized well-defined poly(acrylonitrile-co-N,N-dimethylacrylamide)-block-poly(ethylene glycol)-block-poly(acrylonitrile-co-N,N-dimethylacrylamide) ABA triblock copolymers with various molecular weights and copolymer compositions by reversible addition-fragmentation chain-transfer polymerization. The ratio of acrylonitrile (AN)/N,N-dimethylacrylamide (DMAA) in the triblock copolymers influences their solubility in liquid electrolytes (LEs) and thermal stability. The highest thermal stability was up to 360 °C, and this was achieved by the polymer with an AN/DMAA ratio of ≤4. The thermal stability was related to excessive randomness in the P(AN-co-DMAA) block that hinders cyclization among nitrile groups. Both the molecular weights and the AN/DMAA ratios enabled gel formation by controlling the amount of the polymer, and hence, they influence the ionic conductivity and diffusion as well. Based on the electrochemical properties, polymers with molecular weights above 100 kg/mole were efficient as PGEs in QSS-DSSCs. The overall power conversion efficiency (PCE) of 14 wt % SGT-626 PGE-based QSS-DSSCs was 9.72% under AM 1.5G solar illumination, comparable with an overall PCE of 9.79% for LE DSSCs. The overall PCE of the QSS-DSSCs further increased to 10.02% by incorporating 3 wt % TiO2 nanoparticles in the 14 wt % SGT-626 PGE. The SGT-626 PGE-based QSS-DSSC was also tested under indoor light conditions, and the best PCE of 21.26% was achieved under a white LED light of 1000 lux, which is higher than the PCE of 19.94% for the LE DSSC. The long-term device stability test under adverse conditions (50 °C and 1 sun illumination) reveals the improved stability of PGE-based QSS-DSSCs over LE DSSCs. In terms of PCE and long-term device stability, our PGE QSS-DSSCs have great potential over LE DSSCs for future indoor and outdoor applications.

A polyelectrolytic polyacetylene for quasi-solid state dye-sensitized solar cell applications

A new polyelectrolytic polyacetylene, poly(2-ethynyl-N-iodopyridinium triiodide), was applied for DSSCs. Poly(2-ethynyl-N-iodopyridinium triiodide) was prepared by the non-catalyst polymerization of 2-ethynylpyridine using iodine without any additional initiator or catalyst in high yields. The photoluminescence peak was observed at 534 nm corresponding to a photon energy of 2.32 eV. Quasi-solid-state DSSCs with a SnO2:F/TiO2/D719 dye/solid-state electrolyte/Pt device was fabricated with the poly(2-ethynyl-N-iodopyridinium triiodide) electrolyte, which shows the power conversion efficiency (PCE) of 5.79%.

Review on mixed cation effect in gel polymer electrolytes for quasi solid-state dye-sensitized solar cells

This paper reviews the efforts made to enhance the power conversion efficiencies of dye-sensitized solar cells (DSCs) by employing binary and ternary iodides in gel polymer electrolytes. Reported studies about mixed cation effects in quasi-solid-state electrolytes have been investigated using polyacrylonitrile (PAN), polyvinylidene fluoride, polyvinyl alcohol, polyethylene oxide, polymethylmethacrylate, and phthaloylchitosan as host polymers, with PAN being the most commonly employed. Ionic conductivities, their dependence on the composition of iodide salts, and the nature of counterion have been studied by preparing many different sets of gel polymer electrolytes. DSCs that were fabricated and characterized using different gel polymer electrolytes containing binary salt combinations showed efficiency enhancements. The general trend of open-circuit voltage (Voc) is to increase with an increasing radius of counterion, while short-circuit current density (Jsc) tends to be enhanced with reducing the size of the counterion in the cell. This behavior has been confirmed by studying single salt systems based on alkali metal iodides as well as quaternary ammonium iodides. The studies emphasized a significant enhancement of cell performance for binary cationic systems with respect to their single cation counterparts. In conclusion, the efficiency of the DSCs can be improved by employing a mixed cationic system with high and low charge densities.

Highly porous Ba3Ti4Nb4O21 perovskite nanofibers as photoanodes for quasi-solid state dye-sensitized solar cells

Ternary oxides are considered promising electrode materials for light harvesting devices due to their optical and electronic properties that can be tuned by controlling their composition and doping ratio. Herein, a facile approach is demonstrated to fabricate ternary oxide perovskite nanofibers (NFs) and their investigation investigated as efficient electrode materials in dye-sensitized solar cells (DSSCs). The fabricated electrospun hexagonal perovskite-like (A3B8O21) nanofibers are made of several small single crystals that are connected together to several micrometers in length. Upon sintering to 650 ⁰C, highly porous perovskite nanofibers were obtained, which increased the dye adsorption capacity of the nanofibers and in turn resulted in higher photoconversion efficiency than the traditional nanotubes counterparts. The crystallinity, chemical, and thermal characteristics of the fabricated NFs were investigated using XRD, SEM, TEM, and TGA analyses. Moreover, Brunauer–Emmett–Teller (BET) measurements were used to evaluate the effect of annealing temperature on the pore size and the overall surface area of the NFs. The fabricated nanofibers were used to construct full solar cell devices, revealing enhancement in the overall performance as indicated via the photocurrent-voltage curves. This enhancement is mainly related to the higher adsorption rate of the dye on the nanofibers surface. Highly porous electrospun nanofibers are good platforms that should be useful for the future development of solar cell devices.

Highly efficient indoor light quasi-solid-state dye sensitized solar cells using cobalt polyethylene oxide-based printable electrolytes

High-performance printable electrolytes (PEs) containing Co+2/Co+3 or I−/I3− redox-couple are prepared to fabricate quasi-solid-state (QS) dye-sensitized solar cells (QS-DSSCs) for room light environment applications. Polyethylene oxide (PEO) and poly(methyl methacrylate) (PMMA) are utilized to prepare PEs. Various parameters are regulated to obtain the optimal power conversion efficiencies (PCEs). For the I−/I3− system, the QS-DSSCs using PEO and PEO/PMMA PEs achieve nearly identical PCEs (16.32% and 16.40%, respectively) under the optimal conditions. However, the PCEs obtained for the Co+2/Co+3 system are markedly higher and the cell using PEO PE has a higher PCE (21.06%) than that using PEO/PMMA (18.14%). This difference is ascribed to the different composition of Li+ and Co+3 around the photoelectrode. The presence of Li+ around the interface will repel Co+3 away from the interface, decreasing the recombination of excited electrons to Co+3. According to the molecular structure, PMMA has more lone pair electrons to coordinate with Li+ ions, which will decrease the concentration of free Li+ more significantly than does by PEO. Therefore, the presence of PMMA will decrease and increase, respectively, the Li+ and Co+3 concentrations at the photoelectrode/electrolyte interface, resulting in more significant recombination of electrons to the Co+3. Consequently, the PCE of the PEO/PMMA cell is lower than that of the PEO cell. This effect doesn’t occur in I−/I3− system because the concentration variation of negatively charged ions did not affect significantly the electrons recombination at the interfacial. By using this cobalt PE, a bifacial QS-DSSC can achieve PCEs of 17.22% and 14.25%, respectively, under front-side and back-side illumination by 200 lx T5 light. A sub-module QS-DSSC using the cobalt PE can attain a PCE of 12.56%.

Electrochemically Deposited Polypyrrole for Counter Electrode of Quasi-Solid-State Dye-Sensitized Solar Cell.

In this study, quasi-solid-state dye-sensitized solar cells (QSS-DSSCs) were fabricated by employing polypyrrole (PPy)-functionalized counter electrodes and an iodine-based gel electrolyte. The PPy film was fabricated on a fluorine-doped tin oxide substrate by simple potentiostatic electrodeposition in an aqueous solution using a pyrrole monomer as the precursor. The prepared polypyrrole counter electrode was used in a QSS-DSSC and characterized by scanning electron microscopy and electrochemical impedance spectroscopy. The use of PPy counter electrodes was judged to be acceptable for practical applications because they were only 21% less efficient than counter electrodes fabricated with Pt.

Highly Efficient Dye-sensitized Solar Cells Based on Poly(vinylidene fluoride-co-hexafluoropropylene) and Montmorillonite Nanofiller-based Composite Electrolytes.

Highly efficient nanocomposite electrolytes were prepared by mixing the montmorillonite (MMT) clay nanofillers and iodide poly(vinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) gel electrolytes for the purpose of measuring the performance of quasi-solid-state dye-sensitized solar cells (QS-DSSCs). The impacts of different amounts of MMT nanofillers on the ion diffusivity, conductivity of the polymer gel electrolytes (PGEs), and the photovoltaic performance of the cells using the PGEs were evaluated. The results indicated that the use of 5 wt.% MMT markedly increase the ion diffusivity and conductivity of the PVDF-HFP PGE. The introduction of 5 wt.% nanofillers considerably reduced the Warburg diffusion resistance, which made to the high performance of the QS-DSSCs. Cells utilizing 5 wt.% MMT nanofillers were shown to obtain a power conversion efficiency (PCE) (6.77%) higher than that obtained for cells using pure PGEs and identical to that obtained using liquid electrolytes (LEs) (6.77%). The high PCE was a result of an enhance in the current density in the presence of the 5 wt.% MMT nanofillers. The DSSC efficiency was found to maintain 99.9% of its initial value after 194 h of testing at 60℃ under dark environments. The stability of the DSSC using PGEs with the optimal amount of MMT nanofillers was higher than that for the cells using liquid electrolyte and pure PGE.

Study on the effect of PVDF and TiO2 composition on quasi-solid state DSSC

Dye sensitized solar cell (DSSC) is a third generation solar cell that has become an interesting research topic on energy area due to its properties such as low cost, green technology and simple fabrication. DSSC is mainly constructed with three components consisting of semiconductor photoelectrode, counter electrode and an electrolyte, which usually contains redox couple. Liquid electrolyte is commonly used in standard DSSC device, although it is vulnerable to leakage and susceptible to the environment. Furthermore, liquid electrolyte could react to some kind of sealing material that encapsulates the device as it affects the stability performance. Accordingly, this research attempted to develop quasi-solid-state DSSC (QS-DSSC) by replacing liquid to gel electrolyte in a sandwich structured DSSC with a size of 0.5 cm × 0.5 cm per unit cell. The gel electrolyte prepared in this work was based on liquid electrolyte that was mixed with TiO2 and polymer material in the form of PVDF with various compositions for optimizing the gel electrolyte material. The performance of QS-DSSC samples was obtained using IPCE and I – V measurement, while the viscosity characteristic of the electrolyte was also assessed. The best performance of QS-DSSC sample achieved in this work had short-circuit current density, open-circuit voltage, fill factor, and photoconversion efficiency of 3.708 mA/cm2, 0.637 V, 0.64, and 2.98%, respectively.