Photovoltaic Efficiency Of Dye-sensitized Solar Cells Research Articles

Cost effective dye sensitized solar cell based on novel Cu polypyrrole multiwall carbon nanotubes nanocomposites counter electrode

In order to replace Pt CE in dye sensitized solar cell (DSSC) with simple and low cost, copper polypyyrol functionalized multiwall carbon nanotubes (Cu-PPy-FWCNTS) nanocomposite CE was fabricated by two step electrodeposition method on the stainless-steel substrate. The surface morphology, electrical conductivity, electrochemical properties of Cu-PPy-FWCNTS nanocomposite CE electrodes were observed by using verity of techniques such as scanning electron microscopy, a four-probe method and electrochemical workstation. The Fourier transform infrared (FTIR) spectroscopy confirms the presence of FMWCNTS into PPy-FMWCNTS nanocomposite and XRD analysis verified the Cu nanostructures had come into being. The cyclic voltammogram and Tafel polarization measurement demonstrated that solution processed Cu-PPy-FWCNTS nanocomposites CE had smaller charge transfer resistance Rct (4.31 Ω cm2) and higher electrocatalytic performance for I3−/I− redox solution. Finally, the photovoltaic efficiency of DSSC assembled with Cu-PPy-FWCNTS nanocomposite CE and Platinized CE were compared. The results revealed that the photovoltaic efficiency of DSSC with Cu-PPy-FWCNTS nanocomposites CE reached (7.1%), which is superior to Platinized CE (6.4%). The higher photovoltaic efficiency of the Cu-PPy-FMWCNTS film is due to copper nanostructures that lead to higher cathodic current density (2.35 mA/cm2). The simple fabrication method, excellent electrocatalytic and photovoltaic properties permit the Cu-PPy-FWCNTS nanocomposites credible alternative CE to save the cost of DSSC.

Facile Synthesis of Nanoporous NiS Film with Inverse Opal Structure as Efficient Counter Electrode for DSSCs.

To satisfy the high requirement of catalytic activity for efficient dye-sensitized solar cells (DSSCs), a novel nanoporous NiS film with inverse opal structure and outstanding electrocatalytic properties was prepared by a facile template-assisted electrodeposition method. The inverse opal structure makes the film have a larger specific surface area and more catalytic sites, thereby result to a higher electrocatalytic activity. Compared with the flat NiS/FTO electrode, this kind of nanoporous NiS film with inverse opal structure has higher catalytic activity and can be used as a cheap and efficient Pt-free electrode to replace the traditional Pt/FTO electrode. It is of great significance to reduce the cost and promote the wide application of DSSCs. This study opens up a new experimental exploration for further improving the catalytic activity of NiS electrode and the according photovoltaic efficiency of DSSCs. The template-assisted electrodeposition method proposed in this work provides a facile method for morphology control and an easy to be realized way to optimize the catalytic performance of the metal sulfides counter electrode.

Synthesis and characterization of novel tetra anchoring A2-D-D-D-A2 architecture sensitizers for efficient dye-sensitized solar cells

Novel metal free organic dyes coded TET(RA)4, TET(CA)4, and TET(QA)4 were designed, synthesized, and characterized as effective sensitizers for dye sensitized solar cells (DSSCs). These new push-pull sensitizers used a strong electron donor consisting of 3,4-ethylenedioxythiophene and two triphenylamine molecules connected together to form a TPA-EDOT-TPA (TET) motif, which is directly connected to tetra anchoring groups (A) without any π-spacers to construct A2-D-D-D-A2 architecture, three different anchoring series, viz. rhodanine-3-acetic acid (RA), cyanoacetic acid (CA), and 2-methyl quinoline-6-carboxylic acid (QA) were employed to investigate the influence of anchoring moieties on the electrochemical, thermodynamic, kinetics, and photovoltaic efficiency of DSSCs. The DSSCs devices showed a maximum overall power conversion efficiency (PCE) = 5.13%, short-circuit current density (JSC) = 12.71 mA.cm−2, open circuit voltage (VOC) = 0.62 V, and fill factor (FF) = 65.36% with a maximum incident photon conversion efficiency (IPCE) = 75% for TET(QA)4. The optical and electrochemical studies showed that TET(QC)4 achieved higher electron injection free energy (ΔG°inj) into CB edge of TiO2 as well as high recombination resistance (Rrec) compared to TET(RA)4, and TET(CA)4, which explains the outstanding charge separation and superior power conversion efficiency (PCE) of TET(QC)4 possessing quinoline-6-carboxylic acid (QC) anchoring group. Molecular modeling calculations using DFT and TD-DFT showed effective charge separation, where HOMO is delocalized over the donor scaffold (TPA-EDOT-TPA), and the LUMO is delocalized over only two anchoring groups on the same side of the donor system, which provides strong HOMO-LUMO overlap as well as intimate electronic coupling with TiO2 nanoparticle surface for electron injection. Further, the calculated values of the energy gaps (E0-0) and ground/excited stated oxidation potentials were in perfect agreement with the experimental results.

Dye-sensitized solar cells based on tungsten trioxide-titanium dioxide nanotube nanocomposite photoanodes

The effect of tungsten trioxide doping on the photovoltaic efficiency of dye-sensitized solar cells (DSSCs) with anodized TiO2 nanotubes was investigated. Tungsten-doped TiO2 nanotubes with different amounts of tungsten were obtained directly by the electrochemical anodizing of titanium in a single-step process using sodium tungstate as the tungsten source. Nanocomposite films features were investigated by scanning electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy and ultraviolet-visible spectroscopy. The photovoltaic efficiencies of fabricated DSSCs were characterized by a solar cell measurement system via the photocurrent-voltage (I–V) curves. It was found that the photovoltaic efficiency of DSSCs with tungsten-doped TiO2 nanotubes (sample WT2) was improved compared to DSSCs with as-prepared TiO2 nanotubes and WT samples fabricated using other tungsten concentrations. This improvement is ascribed to increased dye loading and photocurrent density.

Dye-sensitized solar cells based on Cr-doped TiO2 nanotube photoanodes

The effect of chromium doping on the photovoltaic efficiency of dye-sensitized solar cells (DSSCs) with anodized TiO2 nanotubes followed by an annealing process was investigated. Cr-doped TiO2 nanotubes (CrTNs) with different amounts of chromium were obtained by anodizing of titanium foils in a single-step process using potassium chromate as the chromium source. Film features were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and ultraviolet–visible (UV–Vis) spectroscopy. It is clearly seen that highly ordered TiO2 nanotubes are formed in an anodizing solution free of potassium chromate, and with a gradual increase in the potassium chromate concentration, these nanotube structures change to nanoporous and compact films without porosity. The photovoltaic efficiencies of fabricated DSSCs were characterized by a solar cell measurement system via the photocurrent–voltage (I–V) curves. It is found that the photovoltaic efficiency of DSSCs with CrTNs1 sample is improved by more than three times compared to that of DSSCs with undoped TNs. The energy conversion efficiency increases from 1.05 % to 3.89 % by doping of chromium.

Development of Dye Sensitized Solar Cell Using Eco-Friendly Dyes Extracted from Natural Resources

In this study, we investigated the photovoltaic efficiency of DSSC (Dye Sensitized Solar Cell) using five different organic dyes extracted from natural sources namely Gomphrena globosa, Syzygium cumini (fruit and leaf), Crocus sativus, Caesalpinia sappan and Rubia cordifolia. Commercially obtained TiO2 powder, coated over the conducting glass substrate was used as the photo anode and the same coated with carbon soot was used as the photo cathode. UV spectrophotometer and photoluminescence spectrophotometer were used to characterize the dyes to find their absorption and emission maxima respectively. X-Ray diffractometer was used to characterize the TiO2 electrode film. SEM analysis was also carried out to study the surface morphology. The life and efficiency of DSSC can be improved by studying the dye absorption process and the thickness, size and shape of TiO2 coating. Thus, low cost solar cells can be developed with significant power conversion efficiency.Key words: TiO2, DSSC, natural dyes, ITO glass slides, carbon soot, sintering.

Covalent Modification of Photoanodes for Stable Dye-Sensitized Solar Cells

This paper describes the surface modification of TiO2 with 3-aminopropyltriethoxysilane (APTES) followed by covalent attachment of Ru-based N719 dye molecules to TiO2 through an amide linkage for use as photoanodes (PAs) in dye-sensitized solar cells (DSSCs). Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) confirms the surface chemistry between the TiO2 and dye. The photovoltaic efficiency of DSSCs with covalently linked dye is very similar (6-7%) to that of traditionally prepared DSSCs prepared by direct immersion when both have similar dye coverage. Importantly, the efficiency of PAs with covalently linked dye did not change after storage for more than 60 days in air, whereas the traditionally prepared PAs decreased dramatically after 1 day and lost most of their efficiency after a week. FTIR and UV-vis characterization of the dye suggests that covalent linkage improves stability by preventing the loss of the thiocyanato ligands and/or tetrabutylammonium cations on the dye. PAs with covalently linked dye are also more stable toward water, acid, heat, and UV light compared to traditionally prepared PAs and are more stable compared to other modified PAs with dye attached through electrostatic or hydrogen-bonding interactions.

Synthesis of ZnO-decorated TiO2 nanotubes for dye-sensitized solar cells

The effect of ZnO electrodeposition on the photovoltaic efficiency of dye-sensitized solar cells (DSSCs) with anodized TiO2 nanotubes followed by an annealing process was investigated. ZnO were introduced into anodized TiO2 nanotubes on Ti foil by electrodeposition in an aqueous electrolyte containing 10mM Zn(NO3)2 6H2O with different processing time, i.e. 25, 50, 100, and 200s. The surface morphologies and the crystallinity of the ZnO-decorated TiO2 nanotubes were inspected via scanning electron microscopy and transmission electron microscopy, respectively. The photovoltaic efficiencies of fabricated DSSCs were characterized by a solar cell measurement system. In addition, we evaluated the kinetics of the photoelectrochemical phenomena in DSSCs via electrochemical impedance spectroscopy with a focus on exploring the electron lifetime and internal resistance of the cells in a quantitative manner based on an equivalent circuit model. It was found that the photovoltaic efficiency of DSSCs with ZnO-decorated TiO2 nanotubes for 50s was improved by more than 60%, compared to DSSCs with as-prepared TiO2 nanotubes. This improvement is ascribed to increased dye loading and photocurrent density.

Platinum nanoparticles deposited on substrates by solventless chemical reduction of a platinum precursor with ethylene glycol vapor and its application as highly effective electrocatalyst in dye-sensitized solar cells

To deposit nanostructured platinum (Pt) on substrates has fundamental and practical significance as Pt is a noble metal and an effective electrocatalyst. In this paper, we report a facile and scalable method to deposit Pt nanoparticles on substrates through the solventless chemical reduction of H2PtCl6 with vapor of ethylene glycol (EG) below 200°C. The Pt nanoparticles have a size below 6nm, and they homogeneously distribute on the substrates. They have good adhesion to the substrates. They are highly catalytic for the reduction of triiodide that is the chemical reduction at the counter electrode of dye-sensitized solar cells (DSCs). Though DSCs with Pt deposited by the EG vapor reduction and pyrolysis exhibit comparable high photovoltaic efficiency of more than 8% at high Pt loading, the photovoltaic efficiency of DSCs with Pt by the EG vapor reduction is much higher than that by pyrolysis when the Pt loading is quite low. DSCs with a Pt loading of 0.19μgcm−2 deposited by this method can have a power conversion efficiency of 6.61%, which is even higher than that (6.19%) of DSCs with a Pt loading of 0.78μgcm−2 deposited by pyrolysis. Thus, this method can significantly reduce the Pt loading to ¼ or even lower in comparison with Pt by pyrolysis which has been regarded as the method to deposit Pt with the highest electrocatalytic activity as the counter electrode of DSCs. The excellent electrocatalytic activity of Pt is attributed to the small Pt particle size.