Films For Dye-sensitized Solar Cells Research Articles

Fabrication of photoelectrode film using anodic oxidation technique for dye-sensitized solar cells

This study uses TiO2 nanomaterials with three different morphologies and carbon nanotubes to fabricate three layers of films for dye-sensitized solar cell (DSSC) photoelectrodes. The three layers of films with different TiO2 morphologies include highly-ordered TiO2 nanotubes, titania nanotubes after calcinations at 550°C and TiO2 nanoparticle-modified single-wall carbon nanotubes. The study compares the electron transfer performance of the prepared DSSCs are assembled by single-layer, double-layer and triple-layer films of photoanodes. After three different photoanodes are soaked in N719 dye and assembled in DSSCs, their open-loop voltage recession, electrochemical impedance, lifetime, life cycle and effective diffusion coefficient are measured. Electron transfer efficiency of photoanodes and light harvesting efficiency are further analyzed. Results show that the DSSCs prepared by three layers of photoelectrodes films have short-circuit photocurrent density 16.5mA/cm2, open-circuit voltage 0.835, and photoelectric conversion efficiency being as high as 8.52%. Furthermore, the electron transfer efficiency, lifetime, life cycle and effective diffusion coefficient of DSSCs assembled by triple-layer photoanodes are better than those of single-layer or double-layer photoanodes.

Stability of templated and nanoparticles dye-sensitized solar cells: photovoltaic and electrochemical investigation of degradation mechanisms at the photoelectrode interface

A key issue in the commercialization of dye-sensitized solar cells is to maintain high efficiency and long lifetime. As reported in the literature, dye-sensitized solar cells are stable under visible light soaking but thermal stress and UV exposure lead to efficiency degradation. However, all the stability studies published so far have been performed on cells whose TiO2 electrodes were prepared by tape casting or screen printing of nanoparticle pastes/inks. The present study concerns cells based on highly porous templated TiO2 electrodes, whose larger surface area could enhance the negative effects of thermal stress, light soaking and UV exposure. The long-term stability of these cells is compared with a classical nanoparticle-based cell using current-voltage measurements (I-V curves) and electrochemical impedance spectroscopy. Due to their higher active interface, templated cells are more sensitive than nanoparticle cells to UV illumination, although this can be easily solved in both cases by the use of a UV filter. The templated cells are as stable as the nanoparticle cells under visible light soaking (UV filtered). However, we showed that templated cells are more stable under thermal stress. Moreover, as evidenced by electrochemical impedance spectroscopy, templated cells show lower transfer resistance, as well as lower recombination resistance compared to nanoparticle cells. The crystallite connectivity promoted by the templating route seems to favor the electron transfers inside the porous layer. Using templated films in dye-sensitized solar cells is therefore really promising because higher conversion efficiencies are reached without promoting cell degradation.

Laser Sintering of a Porous TiO2 Film in Dye-Sensitized Solar Cells

We investigate the possibility of modifying the porous structure of TiO2 films in dye-sensitized solar cells (DSSC) in its sintering by a pulsed Nd:YAG laser (wavelength 1064 nm) to improve their parameters and characteristics. Sintering at various pulse energies enabled a porosity within the range of 0.45 to 0.20. The efficiency of the energy conversion in experimental DSSC specimens with TiO2 films sintered by an optimum laser-radiation pulse energy of 150 mJ was 20–25% higher than that of commercial solar cells.

Cathodic Electrodeposition of Cobalt Sulfide Thin Films for Dye-Sensitized Solar Cells and Supercapacitors

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Thickness-dependent electron transport performance of mesoporous TiO2 thin film for dye-sensitized solar cells

Anatase titania (TiO 2 ) nanocrystals with an average size of 12 nm were synthesized by combining sol–gel method and hydrothermal crystallization technology. Mesoporous TiO 2 thin film electrodes (MTTFEs) were prepared by variations in layer of screen-printed TiO 2 nanocrystals pastes, and dye-sensitized solar cells (DSCs) based on different thickness of MTTFEs were fabricated with dye C106. Under the irradiation of 100 mW cm −2 air mass 1.5 global (AM1.5G) sunlight, the short-circuit photocurrent density ( J sc ) and overall conversion efficiency ( η ) was improved when the thickness of MTTFEs increased from 2.1 μm to 9.8 μm, and obvious decreases of the J sc and η were found when the film thickness was further increased over 9.8 μm. The kinetic parameters of electron transport were investigated by the transient photoelectrical and electrical impedance measurements, and then the influence of MTTFEs thickness on electron transport performance in DSCs were further discussed. The results showed that the density of states ( DOS ) and recombination rate ( K r ) increased with the MTTFEs thickness increasing. Furthermore, when the thickness of MTTFEs was in the range of 2.1–9.8 μm, the electron lifetime ( τ n ), the electron diffusion coefficient ( D n ), and the electron diffusion length ( L n ) of devices increased, but these parameters decreased gradually with the further increased thickness of MTTFEs, which influenced the electronic transport performance of DSCs.

Tin Oxide Microspheres with Exposed {101} Facets for Dye‐sensitized Solar Cells: Enhanced Photocurrent and Photovoltage

Hierarchical SnO2 microspheres with exposed {101} facets are synthesized by a one-pot solvothermal reaction and explored as a scattering layer on top of a SnO2 nanoparticle film for dye-sensitized solar cells (DSCs). The microspheres not only enhance photon harvesting by effective light scattering/reflecting but also improve the energy level of the conduction band edge of the SnO2 photoanode, which leads to a simultaneous increase of the short-circuit photocurrent by 17% and open-circuit photovoltage by 20%. An improved overall conversion efficiency of 3.46% is achieved for DSCs using the SnO2 microspheres, which is the highest value reported so far for pure-SnO2 DSCs. Moreover, the SnO2 -microsphere DSCs exhibit a better photostability than the conventional TiO2 DSCs under simulated full sunlight.

A simple template-free ‘sputtering deposition and selective etching’ process for nanoporous thin films and its application to dye-sensitized solar cells

A facile and straightforward method is suggested to synthesize nanoporous-TiO2 thin films for dye-sensitized solar cells (DSSCs). Silver/TiO2 co-sputtering led to the formation of nanocomposite films which consisted of silver nanoclusters with surrounding TiO2 matrices, and metal particles were subsequently etched by just immersing in nitric acid. Nanoporous-TiO2 DSSCs fabricated by this simple and effective process showed power-conversion efficiencies of up to 3.4% at a thickness of only 1.8 μm, which is much superior to that of conventional nanoparticulate-TiO2 DSSCs with similar thickness.

Preparation and Characterization of Nanocrystalline CuS Thin Films for Dye-Sensitized Solar cells

A dye-sensitized nanocrystalline copper sulphide (CuS) solar cell is developed using crystal violet (CV) as a photosensitizer. Nanocrystalline CuS thin film is deposited on indium tin oxide- (ITO-) coated glass substrate by chemical bath deposition (CBD) technique. These thin films are characterized for their structural, optical and electrical properties using X-ray diffractometer (XRD), atomic force microscopy (AFM), and scanning electron microscopy (SEM). Optical absorbance measurements from UV-visible spectrometer at normal incidence of light in the wavelength range of 320–1100 nm and current-voltage (I-V) measurements were also made. The deposited CuS thin film on ITO-coated glass substrate may be used as a photo electrode in the fabrication of dye-sensitized solar cell (DSSC). The carbon soot collected on the substrate is used as a counter electrode. The counter electrode coupled with a dye-sensitized CuS thin film along with a redox electrolyte mixture is used to develop a complete photovoltaic cell. The fill factor and efficiency were evaluated for the developed DSSC.

Preparation and characterization of TiO2 anode film with hierarchical structure by photo-induced polymerization method

The TiO2 photoanode film with hierarchical structure which consists of porous structure and spinodal phase separation structure with macroporous continuous skeleton was fabricated by photopolymerization induced phase separation method. The influence of the different photomonomers, different coating layers and different heat treatment temperatures on the structure and photoelectric property of TiO2 film has been investigated and the possible mechanism was proposed. The performances of the TiO2 anode film were characterized by scanning electron microscopy, X-ray diffraction and I–V test. The results indicated that, in contrast with the TiO2 anode film with single structure, the as-prepared TiO2 anode film with hierarchical structure showed higher photoelectric conversion efficiency which is 0.272 %. Even though the photoelectric conversion efficiency is not very high, the strategy presented in the paper should be valuable and it still provides the ideas for the new structure and new preparation method on photoanode film of dye-sensitized solar cells, meanwhile, it lays the foundation for designing the solar cells with high photoelectric conversion efficiency.

Influence of acid/base co-catalyst on the photoelectrochemical properties of TiO2 thin films in dye-sensitized solar cells

Photoelectrochemical properties of TiO2 thin films via co-catalyst sol–gel reaction for dye-sensitized solar cells (DSSCs) were investigated. Three different types of nanocrystalline TiO2 thin films were fabricated from the hydrolysis of Ti isopropoxide with various proportions of an acid/base co-catalyst. The acid/base co-catalyst with a lower proportion of base catalyst reduces particle size of the TiO2 and increases its cluster size including pore volume, which enhance short-circuit current density and open-circuit voltage of the DSSCs device by reducing charge transfer loss across the TiO2/redox electrolyte interface.

Effect of post-heat-treated NiOx overlayer on performance of nanocrystalline TiO2 thin films for dye-sensitized solar cells

In this study, nanostructured TiO2 electrodes are coated with a NiOx overlayer by reactive direct currrent magnetron sputtering for dye-sensitized solar cells (DSSC). The effects of a 10-min heat treatment at 450 °C in a rapid thermal annealing system under vacuum, TiO2/NiOx(vacuum), and under ambient atmosphere, TiO2/NiOx(air), has been intensively investigated.For a TiO2/NiOx(air) electrode, the cell conversion efficiency (η) can be enhanced substantially due to the 10% increase in amount of N719 dye adsorbed on TiO2 surface as compared with a bare TiO2 electrode. The basic NiOx-coated surface favours dye attachment through its carboxylic acid groups since the isoelectric point (IEP) of NiO (pH 10.3) is higher than that of anatase TiO2 (pH 6.2). Electrochemical impedance spectroscopy analysis (EIS) shows that a NiOx overlayer suppresses the transport of photoelectrons from TiO2 to the electrolyte. It is proposed that IEP of NiOx(air) is higher than that of NiOx(vacuum). The more basic TiO2/NiOx(air) surface leads to an increment in dye adsorption which consequently facilitates the transport of electrons at the TiO2/dye interface and results in better light harvesting. For TiO2/NiOx(air) electrode, the best η of 7.31% with Jsc and Voc of 24.2 mAcm−2 and 0.80 V, respectively are obtained.

A review of zinc oxide photoanode films for dye-sensitized solar cells based on zinc oxide nanostructures

Zinc oxide (ZnO) is a unique semiconductor material that exhibits numerous useful properties for dye-sensitized solar cells (DSSCs) and other applications. Various thin-film growth techniques have been used to produce nanowires, nanorods, nanotubes, nanotips, nanosheets, nanobelts and terapods of ZnO. These unique nanostructures unambiguously demonstrate that ZnO probably has the richest family of nanostructures among all materials, both in structures and in properties. The nanostructures could have novel applications in solar cells, optoelectronics, sensors, transducers and biomedical sciences. This article reviews the various nanostructures of ZnO grown by various techniques and their application in DSSCs. The application of ZnO nanowires, nanorods in DSSCs became outstanding, providing a direct pathway to the anode for photo-generated electrons thereby suppressing carrier recombination. This is a novel characteristic which increases the efficiency of ZnO based dye-sensitized solar cells.

Surfactant influence in the performance of titanium dioxide photoelectrodes for dye-sensitized solar cells

The semiconductor thin film of dye-sensitized solar cells (DSCs) photoelectrodes is commonly fabricated from a paste containing TiO2 nanoparticles and whatever surfactant as a thickener or stabilizer. The aim of this paper is to study the influence of the type and quantity of the paste surfactant on the photoelectrode film features and cell performance. To this end, identical techniques and materials, except the film paste surfactant, will be used. Seven pastes are prepared with three surfactants in different quantities: Triton X-100® (T), polyethylene glycol 2000 (PEG) and ethyl cellulose (EC). The effects on the mesoporous film (film thickness and surface features like evenness, presence of cracks or aggregates, etc.) are studied because they are expected to play a major role in the performance of the DSC. The main finding is that the thickness of the TiO2 film strongly depends on the surfactant type and concentration. Fully operating DSCs have been manufactured using a natural dye as sensitizer and a liquid electrolyte, and their energy conversion efficiencies have been measured in environmental conditions. Higher efficiencies are obtained for thicker TiO2 films, thus showing the influence of the paste surfactant on the cell performance. Although the film surface characteristics are also influenced by the surfactant type and quantity, no clear correlation has been found between surface morphology and cell performance.

One-pot synthesis of peacock-shaped TiO2 light scattering layer with TiO2 nanorods film for dye-sensitized solar cells

A titanium dioxide (TiO2) film, showing distinctive functions and morphology, was prepared using the hydrothermal method by controlling the ratio of HCl:CH3COOH in acidic medium. A one-dimensional (1-D) TiO2 nanorod (NR) film was synthesized with a length of 2μm using a 1:2 ratio of HCl:CH3COOH, whereas a 1-D TiO2 NR film with peacock shaped TiO2 nanobundles as a light scattering layer (LSL) was acquired by employing a 2:1 ratio of HCl:CH3COOH. This LSL exhibited remarkable dual functions with respect to high light harvesting, which was attributable to the large surface area of the micrometer-sized TiO2 nanobundles, consisting of small-sized TiO2 NRs of 30–40nm in diameter and a light scattering effect in the long wavelength region of 550–700nm. Accordingly, the dual functions of the LSL resulted in a sharp increase in conversion efficiency (3.93%) that was about twice that (1.49%) of TiO2 NR film synthesized using a 1:2 ratio of HCl:CH3COOH. In particular, a considerably enhanced short-circuit photocurrent (Jsc) was mainly responsible for the resulting increase in overall efficiency with a moderate increase in fill factor and slightly reduced open-circuit voltage.

In situ measurement of dye adsorption on TiO2 thin films for dye-sensitized solar cells

To evaluate the amount of dye molecules adsorbed on TiO2 thin films in dye-sensitized solar cells (DSSCs), it is essential to conduct the adsorption of dyes and desorption with NaOH. However, these steps are complex, time-consuming and prone to inaccuracy. A novel adsorption apparatus was made in our laboratory to understand the adsorption mechanism of dye molecules on TiO2 thin film and also obtains the precise adsorption amount without a desorption step. The commercial and natural dyes, N719 and gardenia yellow, respectively, were employed to measure the adsorption kinetic data, which were analyzed by pseudo-first-order and pseudo-second-order models. It was found that the adsorption apparatus developed in this work for DSSCs was very effective and enabled the precise measurement of the amount of dye adsorbed on the TiO2 thin film directly without a desorption step.

Seed free and low temperature growth of ZnO nanowires in mesoporous TiO2 film for dye-sensitized solar cells with enhanced photovoltaic performance

We report in this paper a cheap and easy method for the preparation of ZnO nanowire/TiO2 nanoparticle hybrid films for applications in dye-sensitized solar cells (DSCs), which is achieved by post-embedding ZnO nanowires in mesoporous TiO2 film via a seed free low-temperature hydrothermal process. The electron transport and recombination properties in the as-fabricated DSCs are studied by using electrochemical impedance spectroscopy. Results indicate that the electron transport, electron lifetime, effective diffusion length and the electron collection efficiency are increased, while the charge recombination is reduced, resulting in the remarkably enhanced power conversion efficiency of 7.46%, higher than 6.09% of standard TiO2 nanoparticle based DSCs.

Fabrication of well-arrayed plasmonic mesoporous TiO2/Ag films for dye-sensitized solar cells by multiple-step nanoimprint lithography

Download options Please wait... Article information DOI https://doi.org/10.1039/C3TA10882A Article type Paper Submitted 01 Mar 2013 Accepted 28 Mar 2013 First published 28 Mar 2013 Download Citation J. Mater. Chem. A, 2013,1, 6433-6440 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions Fabrication of well-arrayed plasmonic mesoporous TiO2/Ag films for dye-sensitized solar cells by multiple-step nanoimprint lithography W. Jiang, H. Liu, L. Yin and Y. Ding, J. Mater. Chem. A, 2013, 1, 6433 DOI: 10.1039/C3TA10882A To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Social activity Tweet Share Search articles by author Wei Jiang Hongzhong Liu Lei Yin Yucheng Ding

Spectroscopic and Morphological Studies of Metal-Organic and Metal-Free Dyes onto Titania Films for Dye-Sensitized Solar Cells

We have investigated the spectroscopic behavior of three different sensitizers adsorbed onto titania thin films in order to gain information both on the electron transfer process from dye to titania and on the anchorage of the chromophore onto the semiconductor. We have examined by UV-Vis and fluorescence spectroscopy the widely used ruthenium complexcis-di(thiocyanato)bis(2,2′-bipyridyl-4,4′-dicarboxylato)ruthenium(II) (N719), the more recently developed organic molecular 3-(5-(4-(diphenylamino)styryl)thiophen-2-yl)-2-cyanoacrylic acid (D5), and apush-pullzinc phthalocyanine sensitizer (ZnPc). Three type of titania films with different morphology, characterized by SEM and FT-IR measurement, were considered: a mesoporous transparent film deposited by spin-coating (TiMS), a semiopaque film deposited by doctor-blade from mesoporous titania (TiMS_DB) and a semiopaque film deposited by doctor-blade form commercial P25 titania (P25_DB). The use of TiMS is responsible for the adsorption of a higher amount of dye since the mesoporous structure allows increasing the interfacial area between dye and titania. Moreover, the fluorescence emission peak is weaker when the sensitizers are adsorbed onto TiMS. These findings suggest that mesostructured films could be considered the most promising substrates to realize photoanodes with a fast electron transfer process.

Collaborational effect of heterolytic layered configuration for enhancement of microwave heating

Microwave irradiation efficiently heats up the microwave-inert materials in the range of applied frequencies when two microwave-inert materials are brought into contact in the layered configuration. This heating is applied for annealing TiO2 nanoporous films for dye-sensitized solar cells achieving a one order of magnitude more rapid annealing process for comparable performances.

TiO2 Film Morphology, Electron Transport and Electron Lifetime in Ultra-fast Sintered Dye-sensitized Solar Cells

ABSTRACTWith the application of near-infrared radiation (NIR), TiO2 films for dye-sensitized solar cells (DSCs) on metallic substrates can be sintered in just 12.5 s. The photovoltaic performance of devices made with NIR sintered films match those devices made with conventionally sintered films prepared by heating for 1800 s. Here we characterise the electron transport, electron lifetime and phase-morphological properties of ultrafast NIR sintered films, using impedance spectroscopy, transient photovoltage decay and x-ray diffraction measurements. An important factor in NIR processing of TiO2 films is the peak metal temperature (PMT) and we show that during the 12.5 second heat treatment that a PMT of around 635 °C gives near identical electron transport, electron lifetime and morphological properties, as well comparable photovoltaic performance to a conventionally sintered (500 °C, 30 mins) film. What is perhaps most interesting is that the rapid heating of the TiO2 (to temperatures of up to 785°C) does not lead to a large scale rutile phase transition. As such photovoltaic performance of resultant DSC devices is maintained even though the TiO2 has been at temperatures which traditionally would have reduced cell photocurrents via anatase-to-rutile phase transition.