PSS Counter Electrode Research Articles

The first application of water-soluble ruthenium phenanthroline complex for dye sensitized solar cells from aqueous solution using PEDOT:PSS counter electrode versus platinum counter electrode

Photovoltaic properties of RuII(4,7-diphenyl-1,10-phenanthroline-disulfonic acid disodium salt)-bis(2,2′-bipyridine), [Ru(L1)(bpy)2](PF6)2, [K403] related to its adsorption behaviour onto the nanoporous titanium oxide are investigated in association with its water-soluble structure thanks to disulfonic acid disodium salt groups. Dye sensitized solar cell is fabricated from aqueous solution of water-soluble ruthenium complex. Devices are fabricated in a sandwich geometry using PEDOT:PSS counter electrode versus platinum counter electrode. Poly(3,4-ethylendioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS) is coated on FTO conducting glass substrate by spin coating process and used as dye sensitized solar cell’s counter electrode. Our device performance results show that PEDOT:PSS counter electrode in DSSC has reasonably good catalytic activity and can be used instead of platinum counter electrode. The energy conversion efficiency is significantly favourable for DSSC using PEDOT:PSS counter electrode. The optical and electrochemical behaviours of K403 are studied. Also cyclic voltammograms and estimated by density functional theory studies (DFT) are studied for calculating EHomo and ELumo energy levels of ruthenium complex.

Polyethylene glycol-modified poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) counter electrodes for dye-sensitized solar cell

Poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) counter electrodes, doped with polyethylene glycol (PEG) and acetylene black as binding and conductivity promoting agent, were prepared by a simple mixing method for dye-sensitized solar cell. The electrochemical properties of the electrodes were characterized by cyclic voltammetry, electrochemical impedance spectroscopy (EIS), and Tafel polarization curves. Using PEG dopant, the electrocatalytic activity of PEDOT:PSS electrode was much improved, and further improved by adding a small amount of conducting acetylene black (0.2 wt%). The DSSC cells, using the PEDOT:PSS electrode with PEG (5 wt%) dopant and the composite electrode with PEG (5 wt%)/acetylene black, exhibited an energy conversion efficiency of 3.57 and 4.39 %, comparable with 4.50 % of the commonly used Pt electrode under the same experimental conditions. These results demonstrate that PEG-modified PEDOT:PSS counter electrode is promising to replace the expensive Pt for low cost DSSC, especially to meet the large-scale fabrication demands.

High-efficient dye-sensitized solar cell based on highly conducting and thermally stable PEDOT:PSS/glass counter electrode

The conductivity and thermal stability of PEDOT:PSS film can be enhanced by adding some organic solvents such as EG (ethylene glycol) and HFIP (hexafluoro-isopropyl alcohol) in PEDOT:PSS aqueous solution. The amphiphilic HFIP has the hydrophobic CF3 groups to interact with the hydrophobic PEDOT chains, while the hydrophilic OH group preferentially interacts with the hydrophilic PSS chains in the solution. M-PEDOT:PSS film spin coated (or casted) from the PEDOT:PSS/H2O/EG/HFIP mixed-solvent solution thus is highly conducting and thermally stable. Compared to PEDOT:PSS film made from PEDOT:PSS/H2O aqueous solution, M-PEDOT:PSS film has a denser packing, better ordered and clearer phase (PEDOT and PSS) segregation as revealed with AFM and X-ray diffraction data. M-PEDOT:PSS film (4μm in thickness), with a sheet resistant of 1.3Ωsq−1, can be used to replace FTO as a counter electrode in dye-sensitized solar cell (DSC). Furthermore taking the advantage of the difference in solubility but good compatibility between PEDOT:PSS and PEDOT, a layer of PEDOT can be casted on top of M-PEDOT:PSS to be a redox catalyst. DSC based on PEDOT/M-PEDOT:PSS counter electrode, N719 sensitizer, and I-/I3- liquid electrolyte has an efficiency of 7.29% which is close to that (7.62%) for DSC based on thermal-Pt/FTO counter electrode assembled under the same conditions.

Functionalized graphene/poly(3,4-ethylenedioxythiophene):polystyrenesulfonate as counter electrode catalyst for dye-sensitized solar cells

A (grapheme/poly(3,4-ethylenedioxythiophene):polystyrenesulfonate) graphene/PEDOT:PSS composite film was electrodeposited on fluorine-doped tin oxide conductive substrate by one-step electrochemical polymerization method. The low-cost and platinum-free film was used as counter electrode in (dye-sensitized solar cell) DSSC. The cyclic voltammetry, electrochemical impedance spectroscopy and Tafel measurements indicate that the graphene/PEDOT:PSS composite film has low charge-transfer resistance on the electrolyte/electrode interface and high catalytic activity for the reduction of triiodide to iodide and. As a result, the DSSC based on the graphene/PEDOT:PSS counter electrode showed high power conversion efficiency of 7.86% under a simulated sunlight illumination of 100 mW cm−2 (AM 1.5), which is comparable with the performance of the DSSC based on Pt counter electrode (7.31%).

A dye-sensitized solar cell based on PEDOT:PSS counter electrode

A counter electrode for dye-sensitized solar cell (DSSC) was prepared by coating poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) with high transparency and adhesion on a conducting FTO glass at low temperature. The surface morphology, conductivity, sheet resistance, redox properties and photoelectric properties of the PEDOT:PSS/carbon electrodes were observed using scanning electron microscopy, a four-probe tester and a CHI660D electrochemical measurement system. The experimental results showed that DSSCs had the best photoelectric properties for PEDOT:PSS/carbon counter electrodes annealed at 80°C under vacuum conditions. The overall energy conversion efficiency of the DSSC with PEDOT:PSS/carbon counter electrode and barrier layer reached 7.61% under irradiation from a simulated solar light with intensity of 100 mW/cm2 (AM 1.5). The excellent photoelectric properties, simple preparation procedure and low cost allow the PEDOT:PSS/carbon electrode to be a credible alternative electrode for use in DSSCs.

Unusual particle-size-induced promoter-to-poison transition of ZrN in counter electrodes for dye-sensitized solar cells

It is well-known that promoter and poison are two contradictory properties of materials. However, in this work, an unusual particle-size-induced promoter-to-poison transition of ZrN has been observed for the counter electrode of poly(3,4-ethylene-dioxythiophene):polystyrene sulfonate (PEDOT:PSS) in dye-sensitized solar cells (DSSCs). If the primary crystal particle size of ZrN is 37 nm, it plays a promoting role for PEDOT:PSS counter electrodes, leading to a remarkable increase in DSSC power conversion efficiency. In contrast, when its primary crystal particle size is decreased to 21 nm, ZrN becomes a serious poison for PEDOT:PSS counter electrodes. This finding would be important for the development of highly efficient DSSC counter electrodes.

Efficient ZnO-based counter electrodes for dye-sensitized solar cells

ZnO is usually exploited as a photoelectrode for dye-sensitized solar cells (DSSCs), but it has not been applied as a DSSC counter electrode. Herein, it is reported that ZnO with poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) could be an efficient DSSC counter electrode with a maximum power conversion efficiency of 8.17%. Furthermore, it was found that the conversion efficiency of DSSCs with the ZnO/PEDOT:PSS counter electrode strongly depends on the ZnO content. Density functional theory (DFT) calculations, electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV) measurements revealed that the variation of the conversion efficiency with ZnO content is determined by the fill factor (FF), which is dependent on the combination of the catalytic activity of ZnO and the conductivity of PEDOT:PSS.

Concentration effect of multiwalled carbon nanotube and poly(3, 4-ethylenedioxythiophene) polymerized with poly(4-styrenesulfonate) conjugated film on the catalytic activity for counter electrode in dye sensitized solar cells

Conductive and catalytic multiwalled carbon nanotube (MWCNT)/poly(3,4-ethylenedioxythiophene) polymerized with poly(4-styrenesulfonate) (PEDOT:PSS) composite films were prepared by dispersing MWCNT in the PEDOT:PSS aqueous solution using ultrasonication without any oxidation process. The effect of the MWCNT loading in the PEDOT:PSS solution was studied in terms of the conductivity and catalytic activity. The MWCNT/PEDOT:PSS composite films showed much lower sheet resistance in the range of 730–2150 Ω/□ and higher surface roughness in the range of 25–110 nm than the pure PEDOT:PSS film (980 kΩ/□ and 0.82 nm) depending on the MWCNT content in the composite. The high conductivity and roughness of MWCNT/PEDOT:PSS films enhanced its performance as a catalytic counter electrode in the dye-sensitized solar cell (DSSC). The interface resistance between the MWCNT/PEDOT:PSS film and the electrolyte was evaluated with electrochemical impedance spectroscopy (EIS) and it was confirmed that as the content of MWCNT in PEDOT:PSS solution was increased, the resistance was decreased. The cell efficiency of DSSC with MWCNT/PEDOT:PSS counter electrode was highly improved as the MWCNT concentration in MWCNT/PEDOT:PSS film increases and especially, the DSSC with FTO-free spray coated MWCNT/PEDOT:PSS counter electrode showed excellent sell performance (Jsc: 10.9 mA/cm2, F.F.: 60.6% and n: 5.4%), which is comparable with that with platinum on FTO counter electrode system (Jsc: 13.9 mA/cm2, F.F.: 62.8% and n: 7.1%).

Nano-Prussian blue analogue/PEDOT:PSS composites for electrochromic windows

Owing to the redox reversibility and color-tunable property, Prussian blue (PB) and its analogs (PBAs) have been of interest in the field of electrochromics. However, most PBAs have long lacked an effective method for processing them as uniform and robust thin films on transparent conductive substrates, so the applications of most PBAs for electrochromic windows are not yet realized. Here we propose a composite film approach to tackle this bottleneck. We employ poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) ink as a dispersive medium for spin coating of PBA nanoparticles on indium tin oxide (ITO) glasses. Two kinds of PBAs, highly transparent zinc hexacyanoferrate (ZnHCF) and electrochromically active cobalt hexacyanoferrate (CoHCF) nanoparticles, are prepared and used to prove this idea. From SEM pictures, we find that a uniform nano-ZnHCF film up to 1.76μm in coating thickness can be deposited on the ITO slide, and the morphology of cuboid-shape ZnHCF nanoparticles (200–500nm) is highly dependent on the co-precipitation concentration. Enhanced charge capacity, cycle life and diffusion characteristics for nano-ZnHCF through networking with PEDOT:PSS are demonstrated with cyclic voltammetric (CV) analyses. According to the AC impedance characterization by a new Randles circuit model, it is found that PEDOT:PSS not only serves as a transparent conductive binder for nano-ZnHCF but also acts like a pseudo-capacitor that holds electric charge for facile electron transfer between the nanoparticles. To demonstrate practical devices, a 10×10cm2 WO3 window prototype with a maximum transmittance modulation of 61.6% at 700nm and a polymeric red-green-blue (RGB) device prototype with a low driving voltage of 1.6V are successfully fabricated with the nano-ZnHCF/PEDOT:PSS counterelectrode. The PEDOT:PSS-assisted spin coating also attains a reliable nano-CoHCF thin film that shows vivid red-to-green electrochromism and has an AC impedance feature perfectly explained by the new Randles circuit. To sum up, we believe that the PEDOT:PSS-assisted spin coating can be applied to other nano-PBAs and may help realize the PBA-based electrochromic windows.

Optimization of TiO2 nanoparticle mixed PEDOT–PSS counter electrodes for high efficiency dye sensitized solar cell

Poly(3,4-Ethylendioxythiophene)–Poly(Styrene Sulfonate) (PEDOT–PSS) mixed with titanium dioxide (TiO2) nanoparticles was coated on conductive glass substrate by a doctor blading method and used as dye-sensitized solar cell (DSSC) counter electrodes. The energy conversion efficiency is significantly improved after TiO2 nanoparticle incorporation. This improvement is attributed to an increase in counter electrode catalytic activity and a decrease in counter electrode charge transfer resistance. These phenomena were observed using Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS), respectively. The efficiency of polymer-TiO2 based DSSCs varied with the ratio of small (~25nm) to large (~100nm) TiO2 nanoparticles. The highest efficiency (~8.49%) was obtained with a ratio of 30% large to 70% small (wt/wt) nanoparticles inTiO2 electrodes. This efficiency is superior to that of Pt DSSC (~7.50%).

A red-to-gray poly(3-methylthiophene) electrochromic device using a zinc hexacyanoferrate/PEDOT:PSS composite counter electrode

Abstract In this paper, we describe a novel red-to-gray poly(3-methylthiophene) (PMeT) electrochromic device (ECD) with the aid of a zinc hexacyanoferrate (ZnHCF)/PEDOT:PSS counter electrode. The application of ZnHCF to an ECD is first reported. ZnHCF has long suffered from poor deposition yield problem, but we demonstrate that a robust ZnHCF film can be prepared by spin coating of a liquid suspension composed of ZnHCF nanoparticles and PEDOT:PSS ink on ITO. It was found that the ZnHCF/PEDOT:PSS composite worked much better with PMeT than pure ZnHCF or pure PEDOT:PSS from both electrochemical and optical aspects. With a LiClO4/PC electrolyte, the PMeT ECD having ZnHCF/PEDOT:PSS as its counter electrode could be reversibly switched between its red state (>0.8 V) and its gray state (

Dye sensitized solar cells (DSSCs) based on modified iron phthalocyanine nanostructured TiO 2 electrode and PEDOT:PSS counter electrode

An iron phthalocyanine with tetra-sulphonated substituents (FeTsPc) was used as photosentizer for the development of dye sensitized nanostructured TiO 2 solar cells. The influence of surface modification (TiO 2 film treated with HCl and HNO 3) and thermal annealing of TiO 2 photo-electrode on the performance of dye sensitized solar cell (DSSC) having structure FTO/TiO 2–FeTsPc/electrolyte/PEDOT:PSS (carbon added)/FTO was investigated through the analysis of current–voltage characteristics under illumination and electrochemical impedance spectra (EIS). The improvement in crystallinity of TiO 2, decrease in the internal surface area and adsorbed amount of dye and increase in the lifetime of injected electrons upon thermal annealing of TiO 2 photo-electrode affects the photovoltaic properties of DSSC. The increase in power conversion efficiency of DSSC based on nitric acid treatment for the photo-electrode is mainly attributed to the increase in photocurrent. A comparative photovoltaic investigation of DSSCs using HCl-treated TiO 2 photo-electrode, indicates that the HNO 3-treated photo-electrode retards back electron transfer at the interface with electrolyte and increases the amount of dye.

Photocurrent mechanism and photovoltaic properties of photo-electrochemical device based on PPAT and PPAT:TY blend

The solid state photo-electrochemical cell (PEC) solar energy conversion devices based on pure PPAT and PPAT:TY blend has been fabricated having structure ITO/nc-ZnO/PPAT or PPAT:TY/electrolyte/PEDOT:PSS-ITO and characterized. The redox properties of PPAT and TY were characterized using cyclic voltammetery (CV). The energy levels of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) have been estimated from their CV and UV–vis absorption spectra. The PPAT and PPAT:TY were used as sensitizer for ZnO nano-particle (nc-ZnO) in the film of PEC devices. Device that consist of PPAT:TY/nc-ZnO photoactive electrode showed improved photovoltaic performance over that consist of PPAT/nc-ZnO. This improvement attributed to the formation bulk heterojunction between PPAT and TY resulting efficient exciton dissociation into free charge carrier and photoinduced charge transfer. The photovoltaic performance of the device is further enhanced when the annealed PPAT:TY blend is used as sensitizer, which attributed to the increase in absorption and red shift in the absorption peak upon thermal annealing. This effect is due to the increased crystallinity of PPAT in the blend. PEC assembling with nc-ZnO adsorbed PPAT:TY blend using polar solvent treated PEDOT:PSS coating on ITO as a counter electrode, was studied. It was observed that when DMSO treated PEDOT:PSS counter electrode is used, the photovoltaic performance of the device is highest, which is attributed to enhanced conductivity of PEDOT:PSS and increased surface roughness. The PEC using carbon black (0.2 wt.%) modified DMSO treated PEDOT:PSS counter electrode reached a device efficiency of 5.54% under illumination 10 mW/cm 2. This efficiency is higher than a PEC using untreated PEDOT:PSS as counter electrode. The thermal annealing of nc-ZnO photoelectrode improves the power conversion efficiency of the device, attributed to the increase crystallinity of the ZnO.

Quasi-solid-state dye-sensitized solar cells: Pt and PEDOT:PSS counter electrodes applied to gel electrolyte assemblies

In this paper we present an attempt to substitute liquid electrolyte (LC) dye-sensitized solar cells (DSSCs) by quasi-solid-state constructions (SC) for semi-transparency application adopting organic/inorganic gels in combination with standard (Pt based) and alternative (PEDOT:PSS based) counter electrodes. Gel polymer electrolytes are prepared by incorporating a liquid electrolyte into a polymer matrix such as polymethyl-methacrylate (PMMA) using propylene carbonate (PC) as gelling solvent. SC employing gel electrolytes with a high content in PC have been shown to exhibit increased lifetime up to 70 h under A.M. 1.5 irradiation. Counter electrodes were prepared by an airbrushing and tape casting technique of Pt salt solutions or by spin coating of commercial PEDOT:PSS solution. PEDOT:PSS counter electrodes were found to show similar I 3 −/I − catalytic activities to Pt based counter electrodes and the best SC obtained gave a short circuit current of 2 mA cm −2 and a open circuit voltage of 625 mV.