Studies of solvent effect on the conductivity of 2‐mercaptopyridine‐doped solid polymer blend electrolytes and its application in dye‐sensitized solar cells

Solvents and electrolytes play an important role in the fabrication of dye‐sensitized solar cells (DSSCs). We have studied the poly(ethylene oxide)‐poly(methyl methacrylate)‐KI‐I₂ (PEO‐PMMA‐KI‐I₂) polymer blend electrolytes prepared with different wt % of the 2‐mercaptopyridine by solution casting method. The polymer electrolyte films were characterized by the FTIR, X‐ray diffraction, electrochemical impedance and dielectric studies. FTIR spectra revealed complex formation between the PEO‐PMMA‐KI‐I₂ and 2‐mercaptopyrindine. Ionic conductivity data revealed that 30% 2‐mercaptopyridine‐doped PEO‐PMMA‐KI‐I₂ electrolyte can show higher conductivity (1.55 × 10^?5 S cm^?1) than the other compositions (20, 40, and 50%). The effect of solvent on the conductivity and dielectric of solid polymer electrolytes was studied for the best composition (30% 2‐mercaptopyridine‐doped PEO‐PMMA‐KI‐I₂) electrolyte using various organic solvents such as acetonitrile, N,N‐dimethylformamide, 2‐butanone, chlorobenzene, dimethylsulfoxide, and isopropanol. We found that ac‐conductivity and dielectric constant are higher for the polymer electrolytes processed from N,N‐dimethylformamide. This observation revealed that the conductivity of the solid polymer electrolytes is dependent on the solvent used for processing and the dielectric constant of the film. The photo‐conversion efficiency of dye‐sensitized solar cells fabricated using the optimized polymer electrolytes was 3.0% under an illumination of 100 mW cm^?2. The study suggests that N,N‐dimethylformamide is a good solvent for the polymer electrolyte processing due to higher ac‐conductivity beneficial for the electrochemical device applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42489.     

Iodine-free organic dye sensitized solar cells with in situ polymerized hole transporting material from alkoxy-substituted TriEDOT

An alkoxy-substituted ethylenedioxythiophene (EDOT) trimer is designed and synthesized which has shown a low oxidation potential of 0.50 V versus saturated calomel electrode (SCE). In situ polymerization of the trimer in a thin layer electrolytic cell using organic dye adsorbed on TiO₂ as the working electrode yielded alkoxy-substituted poly(ethylenedioxythiophene) (PEDOT). With D149 as the dye sensitizer and the in situ polymerized polymer as hole-transporting material (HTM), dye sensitized solar cells (DSSCs) were fabricated to show a typical power conversion efficiency of 3.97% under AM 1.5 G (100 mW cm⁻²) illumination. The results show good promise of in situ polymerized conjugated polymers as HTM for iodine/iodide redox-free DSSC applications.     

Synthesis and photovoltaic properties of two side‐chain polymeric metal complexes containing 8‐hydroxyquinoline and fluorene units with Zn(II) and Cd(II)

Two novel side‐chain polymeric metal complexes (PF1 and PF2) containing 8‐hydroxyquinoline and fluorene units with Zn(II) and Cd(II) having donor‐acceptor π‐conjugated structure have been synthesized and characterized using Fourier transform infrared, ¹H NMR, UV‐visible and photoluminescence spectroscopies, thermogravimetric analysis, differential scanning calorimetry, elemental analysis and cyclic voltammetry. Dye‐sensitized solar cells (DSSCs) based on PF1 and PF2 as the dye sensitizers exhibit good device performance with solar‐to‐electricity conversion efficiency up to 0.32% (J_sc = 0.83 mA cm^?2, V_oc = 0.62 mV and FF = 0.62) and 0.24% (J_sc = 0.69 mA cm^?2, V_oc = 0.59 mV and FF = 0.60), respectively, under simulated AM 1.5 G solar irradiation (100 mW cm^?2). The data show that these novel polymeric metal complexes are suitable for DSSCs. Copyright © 2012 Society of Chemical Industry     

In situ electrochemical synthesis of a poly(o‐anisidine) counter electrode for a dye‐sensitized solar cell

Poly(o‐anisidine) (POA) counter electrodes (CEs) were fabricated by potentiodynamic deposition and incorporated into platinum (Pt)‐free dye‐sensitized solar cells (DSSCs). A different sweep number had great impact on the morphology and electrocatalytic activity of the POA films. The POA film fabricated by 25 sweep cycles was observed to have a highly porous morphology, and this resulted in a lower charge‐transfer resistance of 57 cm² in comparison with the Pt CE. The DSSC assembled with the POA CE showed a higher photovoltaic conversion efficiency of 1.67% compared to 1.2% for the DSSC with the Pt CE under full sunlight illumination. Therefore, the high active surface area of the 25‐sweep‐segmented POA film could be considered a promising alternative CE for use in DSSCs because of its high electrocatalytic performance and electrochemical stability. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42041.     

Arylamine polymers prepared via facile paraldehyde addition condensation: an effective hole‐transporting material for perovskite solar cells

Arylamine polymers were prepared via the facile one‐step addition condensation of N,N′‐diphenyl‐N,N′‐bis(4‐methylphenyl)‐1,4‐phenylenediamine and 4‐methoxytriphenylamine with paraldehyde. The polymers were highly soluble in common organic solvents. The non‐conjugated arylamine polymer structure was characterized and found to form tough, homogeneous, amorphous layers with a glass transition temperature above 200 °C on a substrate by a simple spin‐coating process. The polymer layers exhibited a hole mobility of the order of 10^?5 cm² V^?1 s^?1, which was comparable with those of previously reported arylamine polymers, and a highest occupied molecular orbital level of ?5.38 eV appropriate for the hole‐transporting layer of perovskite solar cells. The perovskite cells fabricated with the polymers gave a photovoltaic conversion efficiency of 16.0%. © 2018 Society of Chemical Industry     

Development of quasi‐solid‐state dye‐sensitized solar cell based on an electrospun polyvinylidene fluoride–polyacrylonitrile membrane electrolyte

Dye sensitized solar cell (DSSC) has been magnetizing more awareness in current research due to more efficiency. The foremost drawback of the solar cell is the evaporation of organic electrolyte. In order to address this problem, the polyvinylidene fluoride–polyacrylonitrile–Electrospinning Fibrous Membranes were prepared by electrospinning method and the photovoltaic performances were evaluated. The polyvinylidene fluoride and polyacrylonitrile were mixed in N,N′‐dimethylformamide and acetone at an applied potential of 15 kV. The surface morphology of membrane is interconnected with network structure and a large number of voids were observed from Field Emission Scanning Electron Microscopy images. The electrolyte uptakes up to 310% were observed and it shows an increase in the ionic conductivity up to 6.12 × 10^?2 S cm^?1 at 25°C. The fabricated DSSCs show open circuit voltage (V_oc) of 0.74 V, fill factor (FF) of 0.65 and short circuit current (J_sc) of 6.20 mA cm^?2 at an incident light intensity of 100 mW cm^?2. The photovoltaic efficiency also reached up to 3.09%. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 40022.     

Preparation and characterization of poly(o‐anisidine) with the influence of surfactants on stainless steel by electrochemical polymerization as a counter electrode for dye‐sensitized solar cells

Efficient fast electron transfer from counter electrode to an electrolyte is a key process during the operation of dye‐sensitized solar cells (DSSCs). We introduce a surfactants assisted electro‐polymerized poly(o‐anisidine) (POA) counter electrodes (CE) for DSSCs. Commencing the electrochemical impedance spectroscopy, the POA/sodium dodecyl sulphate (SDS) CE exhibited very low series and charge‐transfer resistance. This is due to high electrocatalytic activity confirmed by cyclic voltammetry, surface area and the conductivity of the stainless steel film. The photovoltaic performance of POA/SDS counter electrode shows an energy conversion efficiency of 2.5% under 1 sun illumination. Short‐term stability test for POA/SDS point out that CE have almost uphold its initial performance. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42310.     

Plasmonic Effects of Infiltrated Silver Nanoparticles Inside TiO2 Film: Enhanced Photovoltaic Performance in DSSCs

The plasmonic effects of infiltrated silver (Ag) nanoparticles, with different contents, inside a nanostructured TiO₂ film on the photovoltaic performance of dye‐sensitized solar cells (DSSCs) are explored. The synthesized Ag nanoparticles are immobilized onto deposited TiO₂ nanoparticles by a new strategy using 3‐mercaptopropionic acid (MPA), a bifunctional linker molecule. Transmission electron microscope (TEM) images show that monodispersed Ag and polydispersed TiO₂ nanoparticles have an average diameter of 12 ± 3 nm and 5 ± 1 nm, respectively. Moreover, Fourier transform infrared spectroscopy (FTIR) analysis reveals that Ag nanoparticles were successfully functionalized and capped with MPA. Optical studies on the MPA‐capped Ag nanoparticles inside TiO₂ film show an increase in the total absorbance of the electrode. Moreover, EIS measurements confirm that MPA‐capped Ag nanoparticles inhibit the charge recombination and improve the stability of nanoparticles in I₃^?/I^? electrolyte. The DSSC assembled with optimal content of MPA‐capped Ag nanoparticles demonstrated an enhanced power conversion efficiency (8.82% ± 0.07%) compared with the pure TiO₂ (7.30% ± 0.05%). The increase in cell efficiency was attributed to the enhanced dye light absorption in strength and spectral range due to the surface plasmon resonance of MPA‐capped Ag nanoparticles in the photoanode.     

Solid‐state dye‐sensitized and bulk heterojunction solar cells using TiO2 and ZnO nanostructures: recent progress and new concepts at the borderline

In the field of photovoltaic energy conversion, hybrid inorganic/organic devices represent promising alternatives to standard photovoltaic systems in terms of exploiting the specific features of both organic semiconductors and inorganic nanomaterials. Two main categories of hybrid solar cells coexist today, both of which make much use of metal oxide nanostructures based on titanium dioxide (TiO₂) and zinc oxide (ZnO) as electron transporters. These metal oxides are cheap to synthesise, are non‐toxic, are biocompatible and have suitable charge transport properties, all these features being necessary to demonstrate highly efficient solar cells at low cost. Historically, the first hybrid approach developed was the dye‐sensitized solar cell (DSSC) concept based on a nanostructured porous metal oxide electrode sensitized by a molecular dye. In particular, solid‐state hybrid DSSCs, which reduce the complexity of cell assembly, demonstrate very promising performance today. The second hybrid approach exploits the bulk heterojunction (BHJ) concept, where conjugated polymer/metal oxide interfaces are used to generate photocurrent. In this context, we review the recent progress and new concepts in the field of hybrid solid‐state DSSC and BHJ solar cells based on TiO₂ and ZnO nanostructures, incorporating dyes and conjugated polymers. We point out the specificities in common hybrid device structures and give an overview on new concepts, which couple and exploit the main advantages of both DSSC and BHJ approaches. In particular, we show that there is a trend of convergence between both DSSC and BHJ approaches into mixed concepts at the borderline which may allow in the near future the development of hybrid devices for competitive photovoltaic energy conversion. Copyright © 2011 Society of Chemical Industry     

In situ thermal polymerization of an ionic liquid monomer for quasi‐solid‐state dye‐sensitized solar cells

In situ thermal polymerization of a model ionic liquid monomer and ionic liquids mixture to form gel electrolytes is developed for quasi‐solid‐state dye‐sensitized solar cells (Q‐DSSCs). The chemical structures and thermal property of the monomers and polymer are investigated in detail. The effect of iodine concentration on the conductivity and triiodide diffusion of the gel electrolytes is also investigated in detail. The conductivity and triiodide diffusion of the gel electrolytes increase with the increasing I₂ concentration, while excessive I₂ contents will decrease the electrical performances. Based on the in situ thermal polymeric gel electrolytes for Q‐DSSCs, highest power conversion efficiency of 5.01% has been obtained. The superior long‐term stability of fabricated DSSCs indicates that the cells based on in situ thermal polymeric gel electrolytes can overcome the drawbacks of the volatile liquid electrolyte. These results offer us a feasible method to explore new gel electrolytes for high‐performance Q‐DSSCs. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42802.     

Stable Tin Chloride Perovskite Sensitized Silver Doped Titania Nanosticks Photoanode Solar Cells with Different Hole Transport Materials

Perovskite sensitized solar cells (PSSCs) have recently been catapulted to the cutting edge of thin-film photovoltaic research and development because of their promise for higher power conversion efficiencies and ease of fabrication. In this work, an attempt has been made to fabricate CH₃NH₃SnCl₃ perovskite sensitized silver doped titania nanosticks photoanode solar cells with an efficient hole transport material (HTM), spiro-MeOTAD, poly(3-hexylthiophene-2,5-diyl) (PTTA) and CuI and attained light to electricity power conversion efficiency (PCE) of 10.46, 7.89 and 6.05 % respectively, under AM 1.5G illumination of 100 mW/cm² intensity. As well, PSSCs made with redox couple electrolytes namely quasi-solid state electrolyte (QSSE) and ionic liquid (IL) electrolyte exhibited the PCE of 4.92 and 3.20 % respectively. A metal oxide (HfO₂) layer is coated on the perovskite sensitized photoanode, which could increase the stability of PSSCs. The current density (Jsc)–open circuit voltage (Voc) study shows that PSSCs made with HTMs exhibited better fill factor and PCE. The electron impedance spectroscopy revealed that the electron lifetime (τ_n), electron mobility (µ) and charge collection efficiency (η_cc)in the PSSCs are in the order spiro-MeOTAD > PTTA > CuI > QSSE > IL. This work expresses that the nature of the HTM is essential for charge recombination and elucidates that finding an optimal HTM for the perovskite solar cell includes controlling the perovskite/HTM interaction.     

Preparation of PAA‐g‐PEG/PANI polymer gel electrolyte and its application in quasi solid state dye‐sensitized solar cells

A microporous hybrid polymer of poly(acrylic acid)‐g‐poly(ethylene glycol)/polyaniline (PAA‐g‐PEG/PANI) is synthesized by a two‐step solution polymerization method. The influence of aniline concentration on the conductivity of PAA‐g‐PEG/PANI gel electrolyte is discussed, when the concentration of aniline is 0.66 wt%, the conductivity of PAA‐g‐PEG/PANI gel electrolyte is 11.50 mS cm^?1. Using this gel electrolyte as host, a quasi solid state dye‐sensitized solar cell (QS‐DSSC) is assembled. The QS‐DSSC based on this gel electrolyte achieves a power conversion efficiency of 6.38% under a simulated solar illumination of 100 mW cm^?2 (AM 1.5). POLYM. ENG. SCI., 55:322–326, 2015. © 2014 Society of Plastics Engineers     

Double‐Layer Structure Photoanode with TiO2 Nanotubes and Nanoparticles for Dye‐Sensitized Solar Cells

Here, we report a novel double‐layer structure photoanode with TiO₂ nanotube (TNT) layer and TiO₂ nanoparticle (TP) layer via a two‐step method of electrochemical anodization and screen printing for dye‐sensitized solar cells (DSSCs). The results indicate that DSSCs with this double‐layer structure have significant advantages of large surface area, long electron lifetime, superior electron recombination restraint characteristics, and high light scattering. The layer thickness of nanotubes and nanoparticles is also investigated and finally an optimized double‐layer structure with excellent performance is prepared. With such a double‐layer structure photoanode, DSSC with a relative high conversion efficiency of 6.43% and a short‐circuit photocurrent density of 16.40 mA·cm^?2 is obtained.     

Microporous gel electrolyte for quasi‐solid‐state dye‐sensitized solar cell

The extension of electrocatalytic reaction of I^?/I₃^? from counter electrode/gel electrolyte interface to gel electrolyte can significantly enhance the redox kinetics and therefore conversion efficiency of dye‐sensitized solar cells. Microporous gel electrolyte from polypyrrole integrated poly(hydroxyethyl methacrylate/cetytrimethylammonium bromide) [PPy‐integrated poly (HEMA/CTAB)] is successfully synthesized by in‐situ polymerization of pyrrole monomers in three‐dimensional framework of porous poly(HEMA/CTAB) matrix. An ionic conductivity of 12.72 mS cm^?1 and activation energy of 8.65 kJ mol^?1 are obtained from PPy‐integrated poly(HEMA/CTAB) gel electrolyte. Tafel polarization and electrochemical impedance spectroscopy are employed to characterize the electrocatalytic behaviors of the gel electrolytes. The resultant quasi‐solid‐state dye‐sensitized solar cell shows a light‐to‐electrical conversion efficiency of 6.68%. POLYM. ENG. SCI., 54:2531–2535, 2014. © 2013 Society of Plastics Engineers     

Triphenylamine-based organic dyes containing benzimidazole derivatives for dye-sensitized solar cells

The synthesis and application to dye-sensitized solar cells of two new triphenylamine-based organic dyes containing benzimidazole derivatives as secondary donors together with a simple triphenylamine derived dye for the purpose of comparison is reported. The photophysical and electrochemical properties of the dyes were investigated by UV–vis spectroscopy and cyclic voltammetry. The introduction of benzimidazole derivatives in the phenyl ring of the triphenylamine core increases the molar extinction coefficients and λ_max because of the extension of the π-conjugation structures of the dyes. Overall conversion efficiencies of ∼2.5% under full sunlight (AM 1.5G, 100 mW cm⁻²) irradiation were obtained for DSSCs based on these new dyes, under the same conditions, the reference dye and di-tetrabutylammonium cis-bis(isothiocyanato) bis(2,2′-bipyridyl-4,4′-dicarboxylato) ruthenium(II) (N719) gave overall conversion efficiencies of 1.23% and 5.61%, respectively. Our findings demonstrate that the introduction of benzimidazole derivatives as secondary donors in triphenylamine-based dye can improve their photovoltaic performance compared to the unsubstituted reference dye in DSSCs.     

Direct (hetero)arylation polymerization for the synthesis of donor–acceptor conjugated polymers based on N‐benzoyldithieno [3,2‐b:2′,3′‐d]pyrrole and diketopyrrolopyrrole toward organic photovoltaic cell application

In this research, new donor–acceptor (D‐A) photovoltaic polymers were synthesized from dithieno[3,2‐b:2′,3′‐d]pyrrole electron donor derivatives, including N‐benzoyldithieno[3,2‐b:2′,3′‐d]pyrrole and N‐(4‐hexylbenzoyl)dithieno[3,2‐b:2′,3′‐d]pyrrole, in combination with the electron deficient unit 2,5‐bis(2‐ethylhexyl)‐3,6‐di(thiophen‐2‐yl)‐2,5‐dihydropyrrolo[3,4‐c]pyrrole‐1,4‐dione via direct (hetero)arylation polymerization. The D‐A conjugated polymers obtained were characterized via ¹H NMR, gel permeation chromatography, Fourier transform infrared spectroscopy, DSC, XRD, photoluminescence and UV–visible methods. In addition, these D‐A polymers were used as activated layers in bilayer and bulk heterojunction structures for the fabrication of organic photovoltaic cells. © 2019 Society of Chemical Industry     

Novel Polymeric Metal Complexes for Dye Sensitizer: Synthesis and Photovoltaic Performances

Four novel polymeric metal complexes with a D–A–π–A motif, BDTT-PY-Cd, BDTT-PY-Zn, BDTT-PY-Cu and BDTT-PY-Ni, were designed, synthesized and characterized. These polymeric metal complexes were made up with Cd(II), Zn(II), Cu(II), Ni(II) complexes, thienylbenzo-[1,2-b:4,5-b'] dithiophene (BDTT) and the 8-quinolinol derivative, which were used severally as dye sensitzers’ auxiliary electron acceptors (A), electron donor (D) and π bridges as well as the acceptors (A). Under AM 1.5 irradiation (100 mW cm^?2), the devices of dye sensitized solar cells (DSSC) based on four polymer complexes exhibited short-circuit photocurrent densities (J_sc) of 17.45 mA cm^?2, 14.75 mA cm^?2, 13.94 mA cm^?2 and 12.00 mA cm^?2, as well as attractive power conversion efficiencies (PCE) of were 9.73%, 8.02%, 6.82% and 6.12%, respectively. The photovoltaic conversion efficiency (PCE) and short-circuit photocurrent density (J_sc) of BDTT-PY-Cd, BDTT-PY-Zn, BDTT-PY-Cu and BDTT-PY-Ni decrease in order because the radius and charge number of the metal ion affect the strength of the coordination bond between the metal ion and the ligand. These results provides a new way of development for efficient and stable dye sensitizers in the future.

     

Synthesis and characterization of poly(1‐vinyl‐3‐propylimidazolium) iodide for quasi‐solid polymer electrolyte in dye‐sensitized solar cells

The synthesis conditions of ionic liquid 1‐vinyl‐3‐propylimidazolium iodide (ViPrIm⁺I⁻) and Poly(1‐vinyl‐3‐propylimidazolium) iodide [P(ViPrIm⁺I⁻)] were studied in this work. P(ViPrIm⁺I⁻) as a single‐ion conductor providing iodine was designed to develop a quasi‐solid polymer electrolyte based on PVDF/PEO film for dye‐sensitized solar cells (DSSCs). The samples were characterized respectively by high‐performance liquid chromatography (HPLC), Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance imaging (NMRI), gel permeation chromatography (GPC), etc. The results showed that the single‐ion conducting quasi‐solid polymer electrolyte (SC‐QPE) exhibited high ionic conductivity of 1.86 × 10⁻³ S cm⁻¹ at room temperature measured by CHI660C Electrochemical Workstation. Moreover, solar cells assembled using the SC‐QPE yielded an open‐circuit voltage of 0.83V, short‐circuit current of 8.01 mA cm⁻² and the conversion efficiency of 2.42%. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Oligomer ethylene glycol based electrolytes for dye‐sensitized solar cell

Oligomer ethylene glycol (O‐EG) based electrolytes without volatile components were prepared and used in dye‐sensitized solar cell (DSSC). The characteristics such as viscosity, ionic conductivity, and ionic activation energy of O‐EG based electrolytes including liquid, gel and solid states were investigated and compared. It is found that the gel and solid O‐EG electrolytes have two E_a values with the changed phase state by going with the increased temperature, and they can increase the onset of applied voltage for generating dark current in DSSCs as from 0.222 V with liquid O‐EG electrolyte to 0.420 V with gel and solid O‐EG electrolytes, which results in the enhanced light‐to‐electricity conversion efficiency from 1.4% with liquid to 1.82% with gel and 1.86% with solid electrolytes. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis and photovoltaic properties of main chain polymeric metal complexes containing 8‐hydroxyquinoline metal complexes conjugating alkyl fluorene or alkoxy benzene by CN bridge for dye‐sensitized solar cells

Four main chain polymeric metal complexes ( P1–P4 ) based on 8‐hydroxyquinoline metal complexes have been synthesized by the Heck coupling and characterized by gel‐permeation chromatography, Fourier transform infrared spectroscopy, proton‐nuclear magnetic resonance, thermogravimetric analysis, ultraviolet–visible absorption, photoluminescence spectroscopy, elemental analysis, and cyclic voltammetry. The applications of these polymers as dye sensitizers in dye‐sensitized solar cells (DSSCs) are also studied. The study results show that the solar cells have good device performance with power conversion efficiency of P1–P4 up to 2.17, 2.04, 2.45, and 2.18%, respectively. The highest power conversion efficiency of DSSCs is up to 2.45%, for P3 consisting of alkoxy benzene unit and Cd–metal complex under the illumination of air mass 1.5 G, 100 mW cm⁻². POLYM. COMPOS., 34:1629–1639, 2013. © 2013 Society of Plastics Engineers