Use In Dye-sensitized Solar Cells Research Articles

Design and fabrication of multi-functional working electrodes with TiO2/CZTSe/bamboo-charcoal-powder composite particles for use in dye-sensitized solar cells

This study developed a multi-functional electrode with composite particles for use in high-efficiency dye-sensitized solar cells (DSSCs). Photoelectron current was enhanced through the inclusion of the visible light absorber Cu2ZnSnSe4 (CZTSe) as well as narrow band gap carbon-doped TiO2 in conjunction with a novel dye absorber, bamboo charcoal powder (BCP). Photoelectron voltage was maintained at a high level through the inclusion of a p–n junction (CZTSe–TiO2). The CZTSe was synthesized using a solvo-thermal process that does not require an autoclave, and BCP was obtained from dehydrated bamboo charcoal. Composites of TiO2 (P-25)/BCP, TiO2 (P-25)/CZTSe, and TiO2 (P-25)/CZTSe/BCP were prepared by wet ball mill grinding prior to the fabrication of DSSC working electrodes. The band gap of the TiO2 (P-25)/CZTSe electrode was shown to decrease with an increase in the quantity of CZTSe; dropping from 2.92 to 2.32eV when the mass ratio of TiO2 to CZTSe changed from 10:0.1 to 10:0.9. Calculations based on density functional theory reveal unintentional substitutions of Cu (to Ti) and Se (to O) atoms contribute to the narrowing of original TiO2 band gap. We also measured the cell performance, including short-circuit photocurrent density (Jsc), open-circuit photovoltage (Voc), and power conversion efficiency (η). The η of DSSCs (6.85%) with a TiO2 (P-25)/CZTSe/BCP electrode (TiO2:CZTSe:BCP=10:0.3:0.6) far exceeded that of conventional DSSCs with a TiO2 (P-25) electrode (3.84%). Of particular note is the fact that the Voc and Jsc of the proposed DSSC exceed those of conventional devices by 9.5% and 100%, respectively. The principles used in the design of the proposed electrode could be extended to all photovoltaic devices.

Asphaltene as Light Harvesting Material in Dye-Sensitized Solar Cell: Resurrection of Ancient Leaves

Asphaltenes are remnants of ancient photosynthetic plants and are today considered waste hydrocarbons that must be removed from petroleum for use as fuel and often find their use as road tar. This study reports the first time their use in Dye-Sensitized Solar Cells (DSSCs) in which light is converted to electricity with conversion efficiencies approaching 1.8%. Extracted fractions of asphaltenes from Mexican Altamira crude oil were used as light absorbers in TiO2 based DSSCs. The photovoltaic performances of the cells were analyzed by determining the I-V cell parameters such as OCV (open-circuit voltage), SCC (short-circuit current), FF (fill factor), and SR (series resistance). The overall energy conversion efficiency was also measured to correlate the effect of the different asphaltene portions that created significant improvement of the solar cell parameters. The sensitization of TiO2 electrode with the best asphaltene fraction resulted in a maximum energy conversion efficiency of 1.8% for the solar cell with a maximum photocurrent density of 16.9 mA/cm2. At this level the solar cell created has strong economic potential. A future strategy to further improve performance by minimizing series resistance and improving the photo current and open circuit voltage is also reported. The cells have shown excellent life as suggested by photo-catalytic polymerization of asphaltene materials when exposed to sunlight and air as stated in patent number 8,389,853.

Theoretical Study of theπ-Bridge Influence with Different Units of Thiophene and Thiazole in Coumarin Dye-Sensitized Solar Cells

Eight coumarin derivative dyes were studied by varying theπ-bridge size with different thiophene and thiazole units for their potential use in dye-sensitized solar cells (DSSC). Geometry optimization, the energy levels and electron density of the Highest Occupied Molecular Orbital and the Lowest Unoccupied Molecular Orbital, and ultraviolet-visible absorption spectra were calculated by Density Functional Theory (DFT) and Time-Dependent-DFT. All molecular properties were analyzed to decide which dye was the most efficient. Furthermore, chemical reactivity parameters, such as chemical hardness, electrophilicity index, and electroaccepting power, were obtained and analyzed, whose values predicted the properties of the dyes in addition to the rest of the studied molecular properties. Our calculations allow us to qualitatively study dye molecules and choose the best for use in a DSSC. The effects ofπ-bridges based on thiophenes, thiazoles, and combinations of the two were reviewed; dyes with three units mainly of thiazole were chosen as the best photosensitizers for DSSC.

Bilayered photoanode consisting of zinc oxide hollow spheres and urchin-like titanium dioxide microspheres enables fast electron transport and efficient light-harvesting for improved-performance dye-sensitized solar cells

Derived from ZnO hollow spheres (ZHSs) as the underlayer and urchin-like TiO2 spheres (UTSs) as the light scattering overlayer, a new bilayered photoanode (ZHS + UTS) is fabricated for use in dye-sensitized solar cells (DSSCs).

Improvement of photovoltaic performance by substituent effect of donor and acceptor structure of TPA-based dye-sensitized solar cells.

We report a computational study of a series of organic dyes built with triphenylamine (TPA) as an electron donor group. We designed a set of six dyes called (TPA-n, where n = 0-5). In order to enhance the electron-injection process, the electron-donor effect of some specific substituent was studied. Thus, we gave insights into the rational design of organic TPA-based chromophores for use in dye-sensitized solar cells (DSSCs). In addition, we report the HOMO, LUMO, the calculated excited state oxidized potential E(dye*)(eV) and the free energy change for electron-injection ΔGinject(eV), and the UV-visible absorption bands for TPA-n dyes by a time-dependent density functional theory (TDDFT) procedure at the B3LYP and CAM-B3LYP levels with solvent effect. The results demonstrate that the introduction of the electron-acceptor groups produces an intramolecular charge transfer showing a shift of the absorption wavelengths of TPA-n under studies. Graphical Abstract Several organic dyes TPA-n with different donors and acceptors are modeled. A strong conjugation acrros the donor and anchoring groips (TPA-n) bas been studied. Candidate TPA-3 shows a promising results.

Triphenylamine-based indoline derivatives for dye-sensitized solar cells: a density functional theory investigation.

A new series of triphenylamine-based indoline dye sensitizers were molecularly designed and investigated for their potential use in dye-sensitized solar cells (DSSCs). Theoretical calculations revealed that modifying donor part of D149 by triphenylamine significantly altered the electronic structures, MO energies, and intramolecular charge transfer (ICT) absorption band. Key parameters associated with the light-harvesting efficiency at a given wavelength LHE(λ), the driving force ΔG inject, and the open-circuit photovoltage V oc were characterized. More importantly, these designed (dimeric) dye sensitizers were found to have similar broad absorption spectra to their corresponding monomers, indicating that modifying the donor part with triphenylamine may stop unfavorable dye aggregation. Further analyses of the dye-(TiO2)9 cluster interaction confirmed that there was strong electronic coupling at the interface. These results are expected to provide useful guidance in the molecular design of new highly efficient metal-free organic dyes.

A Computational and Experimental Study of Thieno[3,4-b]thiophene as a Proaromatic π-Bridge in Dye-Sensitized Solar Cells.

Four D-π-A dyes (D=donor, A=accpetor) based on a 3,4-thienothiophene π-bridge were synthesized for use in dye-sensitized solar cells (DSCs). The proaromatic building block 3,4-thienothiophene is incorporated to stabilize dye excited-state oxidation potentials. This lowering of the excited-state energy levels allows for deeper absorption into the NIR region with relatively low molecular weight dyes. The influence of proaromatic functionality is probed through a computational analysis of optimized bond lengths and nucleus independent chemical shifts (NICS) for both the ground- and excited- states. To avoid a necessary lowering of the TiO2 semiconductor conduction band (CB) to promote efficient dye-TiO2 electron injection, strong donor functionalities based on triaryl- and diarylamines are employed in the dye designs to raise both the ground- and excited-state oxidation potentials of the dyes. Solubility, aggregation, and TiO2 surface protection are addressed by examining an ethylhexyl alkyl chain in comparison to a simple ethyl chain on the 3,4-thienothiophene bridge. Power conversion efficiencies of up to 7.8 % are observed.

Large Area Platinum and Fluorine-doped Tin Oxide-free Dye sensitized Solar Cells with Silver-Nanoplate Embedded Poly(3,4-Ethylenedioxythiophene) Counter Electrode

Low-temperature, cheap, highly conductive triangular silver-nanoplates (Ag-NPs) embedded in poly (3, 4-ethylenedioxythiophene) (PEDOT) films were prepared on bare glass substrates via spin coating and chemical polymerization. The films acted as a very good alternative to conventional platinum (Pt) and fluorine-doped tin oxide (FTO) counter electrodes (CEs) in dye-sensitized solar cells (DSSCs). The effect of the Ag-NPs in the PEDOT CE was evaluated by adding different weight ratios of Ag-NPs (0.06, 0.60, and 1.20wt%) to the PEDOT solution before producing the film, and the catalytic and conductive properties were compared against those of pristine PEDOT films for use in DSSCs. The catalytic properties of all CEs in the DSSCs were characterized via cyclic voltammetry (CV), current-voltage (I-V) measurements, and electrochemical impedance spectroscopy (EIS). The PEDOT CE with embedded Ag-NPs functioned as excellent electrocatalysts for tri-iodide reduction, as compared to pristine PEDOT CEs. DSSCs (cell area: 1cm2) with the 0.60wt% samples exhibited a power conversion efficiency of 6.0% under 1 sun illumination (100mWcm−2), which is higher than that of DSSCs with pristine PEDOT CE (5.5%). The Ag-NPs embedded PEDOT CE has very good catalytic activity and conductivity, which is more suitable for large area Pt and FTO less DSSC. In addition, no noticeable efficiency decay was observed after adding Ag-NPs in PEDOT CEs.

Characteristics of Dye-Sensitized Solar Cells Using TiO2 Nanotube Arrays with Large Surface Area by Spin-Coating Nanoparticle

Highly ordered TiO2 nanotube arrays (TNAs) fabricated by anodization are very attractive for use in dye-sensitized solar cells (DSSCs), because of their superior charge percolation and slow charge recombination. Highly ordered, vertically aligned TNAs have been prepared by three-step anodic oxidation. In this work, we investigated such strategies for improving the efficiency of DSSCs. Based on one of these approaches, oxide semiconductors in the form of a TNA were used as a novel method for improving electron transport through a film. A solution containing an appropriate amount of TiO2 nanoparticles was prepared, and the mixed slurry was spin-coated on a TNA film. The coated film provided a large surface area for dye adsorption. The DSSCs achieved a light-to-electric energy conversion efficiency of 5.91% under simulated solar irradiation at 100 mW/cm2 (AM 1.5).

Novel D–π–A porphyrin dyes with different alkoxy chains for use in dye-sensitized solar cells

A series of novel zinc porphyrin dyes which are featured with a D–π–A structure have been designed and synthesized for use in dye-sensitized solar cells (DSSCs). The influences of different hydrophobic hydrocarbon chains (none, butoxy, octoxy groups) attached at the porphyrin meso-aryl group on the molecules’ photophysical and electrochemical properties, as well as on the photovoltaic performance of the corresponding DSSCs were investigated systematically. The best performance was realized for the cell sensitized with the porphyrin (LP-2) containing a n-butoxy chain on the meso-aryl group and with the acrylic acid as the acceptor. The optimized power conversion efficiency of LP-2 reaches 6.04% with an open-circuit voltage of 730 mV, a short-circuit current density of 11.67 mA cm−2, and a fill factor of 0.71.

Performance Enhancement of Dye-Sensitized Solar Cells Based on TiO₂ Thick Mesoporous Photoanodes by Morphological Manipulation.

This study is an attempt to give an account of the preparation of mesoporous TiO2 thick templated films of nonsimilar pore architecture and their use in dye-sensitized solar cells (DSSCs). Highly crystallized mesoporous titania thick templated films with four different morphologies including hexagonal, wormlike, cubic, and gridlike mesostructure, have been successfully synthesized through an evaporation-induced self-assembly (EISA) route followed by layer-by-layer deposition. Stabilization, followed by each coating, and calcinations, carried out after every five layers, were used to produce crack-free thick films. These mesoporous templated titanium dioxide samples were characterized by TEM, XRD, SEM, BET, and UV-vis measurements and used as a photoelectrode material in DSSCs. The mesostructured films with a thickness of about 7 μm demonstrated better performance in comparison to nanocrystalline TiO2 films (NC-TiO2) at a film thickness of 13 μm as the most typical films utilized in DSSCs. The findings reveal that a surfactant/Ti ratio change undergone for developing cubic mesostructures can enhance the crystallinity and roughness factor and therefore increase the energy conversion efficiency of DSSC. The cell performances derived from these mesofilms were enhanced compared to the efficiencies reported thus far. The best photovoltaic performance of 8.73% came from DSSC using the cubic mesoporous TiO2 photoelectrode with the following properties: open circuit voltage of 743 mV, short circuit photocurrent density of 16.35 mA/cm(2), and fill factor of 0.72.

Thermo-stable carbon nanotube-TiO2 nanocompsite as electron highways in dye-sensitized solar cell produced by bio-nano-process

We produced a thermostable TiO2-(anatase)-coated multi-walled-carbon-nanotube (MWNT) nanocomposite for use in dye-sensitized solar cells (DSSCs) using biological supuramolecules as catalysts. We synthesized two different sizes of iron oxide nanoparticles (NPs) and arrayed the NPs on a silicon substrate utilizing two kinds of genetically modified cage-shaped proteins with silicon-binding peptide aptamers on their outer surfaces. Chemical vapor deposition (CVD) with the vapor–liquid-solid phase (VLS) method was applied to the substrate, and thermostable MWNTs with a diameter of 6 ± 1 nm were produced. Using a genetically modified cage-shaped protein with carbon-nanomaterials binding and Ti-mineralizing peptides as a catalyst, we were able to mineralize a titanium compound around the surface of the MWNT. The products were sintered, and thin TiO2-layer-coated MWNTs nanocomoposites were successfully produced. Addition of a 0.2 wt% TiO2-coated MWNT nanocomposite to a DSSC photoelectrode improved current density by 11% and decreased electric resistance by 20% compared to MWNT-free reference DSSCs. These results indicate that a nanoscale TiO2-layer-coated thermostable MWNT structure produced by our mutant proteins works as a superior electron transfer highway within TiO2 photoelectrodes.

Efficient hydrothermal-processed platinum–nickel bimetallic nano-catalysts for use in dye-sensitized solar cells

Cubic platinum (Pt), nickel (Ni), and PtNi bimetallic nano-crystals with slender tentacles are prepared by a hydrothermal method and used as the counter electrode (CE) materials for dye-sensitized solar cells (DSSCs). The influences of the hydrothermal time on the yield, morphology, electrocatalytic and photovoltaic performances of the PtNi bimetallic nano-crystals are investigated. Cyclic voltammetry and electrochemical impedance spectroscopy measurements indicate that the 2 h hydrothermal-processed PtNi CE has the highest catalytic activity for the reduction of triiodide to iodide and the lowest charge transfer resistance at the electrolyte/electrode interface among PtNi bimetallic CEs. The DSSC based on the 2 h hydrothermal-processed PtNi bimetallic CE achieves a photovoltaic conversion efficiency of 8.95%, which is close to that of the pure Pt CE (9.24%) under full sunlight illumination (100 mW cm−2, AM1.5 G) due to its three-dimensional electrocatalytic surfaces.

Facile, Nonhydrothermal, Mass-Producible Synthesis of Mesoporous TiO2 Spheres for Dye-Sensitized Solar Cells

We report a facile, non-hydrothermal (or non-solvothermal) and mass-producible synthesis of mesoporous TiO2 spheres (MTSs) suitable for use in dye-sensitized solar cells (DSSCs). The synthesis is a facile bulk calcination in which the inexpensive polymer ethyl cellulose (EC) is used as a structure-directing agent; the EC concentration is controlled to induce spherical morphology. The size of MTSs can be adjusted by tuning the solute–solvent interactions; for example, the addition of the poor solvent toluene to the solute resulted in the formation of smaller MTSs. A DSSC fabricated using a polymer electrolyte containing ionic liquid and iodine (I2) and using a layer of MTSs on a nanocrystalline (NC) TiO2 layer exhibited an efficiency of up to 6.3%, which is much higher than those of DSSCs with an NC layer only (5.0%) or with a commercial scattering layer (CSL) on an NC layer (5.7%). A solid-state DSSC (ssDSSC) using a single component solid polymer, namely poly((1-(4-ethenylphenyl) methyl)-3-butyl-imidazolium iodide) (PEBII), also exhibited an excellent efficiency of up to 6.4%. The improved efficiency was due to the role of the MTSs in improving surface area and light harvesting properties, as demonstrated by N2 adsorption/desorption isotherm, UV-visible light absorption, reflectance spectroscopy, incident photon-to-current efficiency (IPCE), and electrochemical impedance spectroscopy (EIS) analyses.

Computational Investigation of Acene-Modified Zinc-Porphyrin Based Sensitizers for Dye-Sensitized Solar Cells

A series of acene-modified zinc-porphyrin dyes (benzene to pentacene, denoted as LAC-1 to LAC-5) were chosen to examine their performance as photosensitizers in dye-sensitized solar cells (DSSCs). Their structural, electronic, and optical properties were investigated at the DFT/TDDFT levels using various theoretical models (i.e., the gas phase model and the implicit/explicit solvent model). The dye@TiO2 complex was used to investigate the dye/semiconductor interfaces using both the cluster and periodic models. After a careful examination of the dependence of the results on different theoretical approaches, some basic principles could be derived based on the theoretical investigation of structure–function relationships in isolated dyes and dye–TiO2 assemblies. Based on these ideas, some general suggestions can be proposed for the future design of dyes for use in DSSCs. For instance, the DFT functionals used in estimating the critical parameters for DSSCs should be carefully validated. Sometimes the performances of the DFT functionals can be improved by a specific energy-shift correction to compensate for systematic errors. Benchmark calculations indicated that the best approach for depicting the reduction potentials is either the M06-2X functional combined with the formula ΔEred = (E0 – E–)GS or the B3LYP functional combined with Koopman’s Theorem. The best functional for estimating the excitation energies was found to be LC-ωPBE. The impact of significant thermal fluctuations on the optoelectronic properties of dyes may also be an important consideration in the prediction of more efficient dyes for use DSSCs. In contrast to the selection of DFT functionals, both the cluster and periodic models resulted in consistent views of the dye–TiO2 interactions, indicating that the use of either model should achieve reasonable results at least in the qualitative manner.

Organic sensitizers possessing carbazole donor and indeno[1,2-b] thiophene spacer for efficient dye sensitized solar cells

Three organic sensitizers consisting of carbazole as an electron donor, indeno[1,2-b]thiophene as the bridging unit have been synthesized and characterized for use in dye-sensitized solar cells. Time-dependent density functional theory studies are indicated that large intramolecular charge transfer takes place from the highest occupied molecular orbital to the lowest unoccupied molecular orbital though the donor is twisted (∼50°) with respect to the π-linker. However, the introduction of indeno[1,2-b]thiophene as a planar π-linker unit is presumed to be the reason for a strong molar absorption coefficient and a red-shifted absorption band. Air mass 1.5 global illumination (100 mW cm−2), the 3-(5-(6-(3,6-bis(2,4-bis(hexyloxy)phenyl)-9H-carbazol-9-yl)-4,4-dimethyl-4H-indeno[1,2-b]thiophen-2-yl)thioph-2-yl)-2-cyanoacrylic acid based device displayed the best performance: an open-circuit voltage of 826 mV, a short-circuit current density of 9.16 mA cm−2, a fill factor of 0.777, and an overall conversion efficiency of 5.88%. Upon changing the electrolyte from iodine to cobalt electrolyte, 3-(5-(6-(3,6-bis(2,4-bis(hexyloxy)phenyl)-9H-carbazol-9-yl)-4,4-dimethyl-4H-indeno[1,2-b]thiophen-2-yl)thioph-2-yl)-2-cyanoacrylic acid based dye-sensitized solar cells gave the remarkably improved overall conversion efficiency (6.66%), which is one of the highest values based on carbazole sensitizers.

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

ABSTRACTPoly(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.

Fabrication of layered hydroxide zinc nitrate films and their conversion to ZnO nanosheet assemblies for use in dye-sensitized solar cells

Layered hydroxide zinc nitrate (LHZN; Zn5(NO3)2(OH)8·xH2O) films were fabricated on glass or plastic substrates by a chemical bath deposition method combined with a homogeneous precipitation in methanolic solutions. High- or low-temperature pyrolytic decomposition of the LHZN films having two-dimensional morphology was attempted to obtain porous ZnO nanosheet-assembly films. The LHZN films were converted into porous ZnO films by pyrolyzing at temperatures above 400 °C, while porous LHZN/ZnO hybrid films were obtained by pyrolyzing at a lower temperature of 120 °C without morphological changes. The pyrolyzed ZnO films were applied to dye-sensitized solar cells (DSSCs), resulting in the generation of relatively high open-circuit voltages. The low-temperature pyrolysis enabled us to fabricate the LHZN/ZnO film even on the plastic substrate. Actually a cell using the LHZN/ZnO film on an indium tin oxide-coated polyethylene naphthalate substrate showed an energy conversion efficiency of 2.08% with a high open-circuit voltage around 0.70 V.

Electron Transfer of Squaraine-Derived Dyes Adsorbed on TiO2 Clusters in Dye-Sensitized Solar Cells: A Density Functional Theory Investigation

Because the intense absorptions of squaraine (SQ) dyes in the red/near-infrared spectral regions closely match the spectral response of sunlight, SQ dyes have great potential for use in dye-sensitized solar cells (DSCs). In this study, we employed density functional theory (DFT) and time-dependent DFT to investigate the structural, optical, and electron transfer properties of seven recently reported SQ-derived dyes adsorbed on a (TiO2)38 cluster having an anatase (101) surface, as a model for corresponding DSCs. In particular, we calculated the proportions of the electron densities in the dye–(TiO2)38 systems that were transferred to the TiO2 moieties upon excitation, allowing us to investigate their electron injection mechanisms. We found that the dye–(TiO2)38 systems followed different direct and indirect mechanisms of electron injection to TiO2 depending on the localization of the excited state electron density and the driving force for excited-state electron injection. JD10 and YR6 owning two intense absorption bands, which have significant proportions of electron density delocalized into the TiO2 moiety upon excitation and have driving forces for excited-state electron injection, followed direct electron injection mechanisms to TiO2. These results are compatible with their higher experimentally observed short-circuit currents (Jsc) than those of the SQ dyes. In contrast, SQ12, SQ2, and SQ4 followed the indirect electron injection mechanism due to their negligible proportion of electron density injected into TiO2; in addition, SQ2 and SQ4 do not provide driving force for electron injection. SQ12, SQ2, and SQ4 dyes had lower experimentally observed Jsc values than those of the other SQ dyes. The calculated probabilities of electron density being delocalized into TiO2 and driving force for excited-state electron injection from these studied SQ dyes are compatible with their experimentally observed Jsc values. This study provides insight into the electron injection mechanisms of SQ-derived dyes adsorbed on TiO2 upon photoexcitation. Furthermore, our calculations and findings give clues for designing new SQ-derived sensitizers for DSC applications.

Enhanced conversion efficiency of dye-sensitized solar cells using a CNT-incorporated TiO2 slurry-based photoanode

A new titanium dioxide (TiO2) slurry formulation is herein reported for the fabrication of TiO2 photoanode for use in dye-sensitized solar cells (DSSCs). The prepared TiO2 photoanode featured a highly uniform mesoporous structure with well-dispersed TiO2 nanoparticles. The energy conversion efficiency of the resulting TiO2 slurry-based DSSC was ∼63% higher than that achieved by a DSSC prepared using a commercial TiO2 slurry. Subsequently, the incorporation of acid-treated multi-walled carbon nanotubes (CNTs) into the TiO2 slurry was examined. More specifically, the effect of varying the concentration of the CNTs in this slurry on the performance of the resulting DSSCs was studied. The chemical state of the CNTs-incorporated TiO2 photoanode was investigated by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. A high energy conversion efficiency of 6.23% was obtained at an optimum CNT concentration of ∼0.06 wt.%. The obtained efficiency corresponds to a 63% enhancement when compared with that obtained from a DSSC based on a commercial TiO2 slurry. The higher efficiency was attributed to the improvement in the collection and transport of excited electrons in the presence of the CNTs.