Nanoparticles For Dye-sensitized Solar Cells Research Articles

Electrosprayed Cu2ZnSnS4 films from its nanoparticles for dye-sensitized solar cells

Electrosprayed Cu2ZnSnS4 films from its nanoparticles for dye-sensitized solar cells

High performance photoelectrodes prepared using Au@P3HT composite nanoparticles for dye-sensitized solar cells

In this study, gold (Au) and poly(3-hexylthiophene) (P3HT) composite nanoparticles (Au@P3HT) are synthesized and applied to modify the photoelectrodes of dye-sensitized solar cells (DSSCs). The modification is carried out by adsorption of Au@P3HT onto the electrode surface. The experimental results show that the Au@P3HT nanoparticles demonstrate a spherical shape with a mean diameter of 6 nm. The analysis of X-ray photoelectron spectroscopy indicates that the P3HT strongly interact with Au, protecting the Au particles from the corrosion of iodide electrolytes. Scanning electron microscope analysis reveals that the Au@P3HT nanoparticles adsorb strongly and uniformly on the mesoporous TiO2 photoelectrode. The UV–vis absorption spectrum shows that the Au@P3HT-modified photoelectrode can enhance the light absorption in the long wavelength region, attributed to the plasmon resonance effect of Au nanoparticles. It also demonstrates that the modification of Au@P3HT not only improves the incident photon to current conversion efficiency but also increases the recombination resistance at the photoelectrode/electrolyte interface. Therefore, the corresponding cell has higher current density and open-circuit voltage. By way of this method, the DSSC can achieve an energy conversion efficiency of 9.34%. The non-corrosive characteristics of the Au@P3HT-modified electrode against the iodide liquid electrolyte improve the durability of the DSSCs.

High Performance Photoelectrodes Prepared Using Au@P3ht Composite Nanoparticles for Dye-Sensitized Solar Cells

High Performance Photoelectrodes Prepared Using Au@P3ht Composite Nanoparticles for Dye-Sensitized Solar Cells

Controllable Core Size of Au@TiO2 through Al(NO3)3 Addition and Its Effects on DSSC Performance

It is known that plasmonic nanoparticles in dye-sensitized solar cells (DSSC) could enhance efficiency through improvement in light absorbance and electron dynamics. Herein we investigated various sizes of AuNP through spontaneous Al(NO3 )3 addition. Core-Shell Au@TiO2 was prepared with various Al(NO3 )3 concentrations of 0.25 mM, 0.5 mM, 0.75 mM and 1 mM. The Au@TiO2 volume fraction of 1% was further added to TiO2 photoanode. Based on the particle size analyzer (PSA) characteristics, the synthesized AuNP’s size was within a range of 34.62 nm – 139.5 nm. The highest efficiency of DSSC was obtained for the sample with the largest AuNP ’s diameter, i.e., 0.0313%, which is about three times higher than pristine DSSC. The increase in efficiency was in accord with Metallic Nanoparticle Boundary Element Method (MNPBEM) simulation, UV-vis spectroscopy, and Incident Photon to Current Conversion Efficiency (IPCE) analysis largest Au core diameter contributes to the strong absorbance and hence the short circuit current

Hydrogen treated TiO2 nanoparticles onto FTO glass as photoanode for dye-sensitized solar cells with remarkably enhanced performance

Hydrogen treatment is a facile and efficient approach for the enhancement in the functioning of TiO2 nanoparticles for dye-sensitized solar cells (DSSC). In this work, TiO2 nanoparticles have been synthesized in the hydrogen environment followed by the deposition onto FTO glass substrates with various film thickness as photoanodes for DSSC. The synthesized hydrogen treated TiO2 nanoparticles based photoanodes have showed significantly improved photocurrent in the resulting fabricated devices. SEM and TEM analyses have confirmed the particle size and morphology of TiO2 nanoparticles at various magnifications. The crystalline structure and phase identification were studied by XRD analysis and Raman spectroscopic measurements. The UV–Vis spectroscopy analysis was carried out to find the response of samples for ultraviolet and visible light. The current-voltage measurements have confirmed the improvement of photocurrent that is principally due to improved photo-activity of hydrogen treated TiO2 nanoparticles. Moreover, hydrogen treated TiO2 nanoparticles-based photoanode with the film thickness of 11.65 μm has remarkably enhanced power conversion efficiency of 6.05% in DSSCs. The ability of highly photoactive hydrogen treated TiO2 nanoparticles will provide the new openings in different fields that include photo-electrochemical water splitting and in many other applications.

Rapid Room-Temperature Synthesis of Mesoporous TiO2 Sub-Microspheres and Their Enhanced Light Harvesting in Dye-Sensitized Solar Cells.

Submicron sized mesoporous spheres of TiO2 have been a potential alternative to overcome the light scattering limitations of TiO2 nanoparticles in dye-sensitized solar cells (DSSCs). Currently available methods for the growth of mesoporous TiO2 sub-microspheres involve long and relatively high temperature multi-stage protocols. In this work, TiO2 mesoporous sub-microspheres composed of ~5 nm anatase nanocrystallites were successfully synthesized using a rapid one-pot room-temperature CTAB-based solvothermal synthesis. X-Ray Diffraction (XRD) showed that the grown structures have pure anatase phase. Transmission electron microscopy (TEM) revealed that by reducing the surfactant/precursor concentration ratio, the morphology could be tuned from monodispersed nanoparticles into sub-micron sized mesoporous beads with controllable sizes (50–200 nm) and with good monodispersity as well. The growth mechanism is explained in terms of the competition between homogeneous nucleation/growth events versus surface energy induced agglomeration in a non-micelle CTAB-based soft templating environment. Further, dye-sensitized solar cells (DSSCs) were fabricated using the synthesized samples and characterized for their current-voltage characteristics. Interestingly, the DSSC prepared with 200 nm TiO2 sub-microspheres, with reduced surface area, has shown close efficiency (5.65%) to that of DSSC based on monodispersed 20 nm nanoparticles (5.79%). The results show that light scattering caused by the agglomerated sub-micron spheres could compensate for the larger surface areas provided by monodispersed nanoparticles.

Apparatus-dependent sol-gel synthesis of TiO2 nanoparticles for dye-sensitized solar cells

Synthesis of titanium dioxide nanoparticles (TiO2 NPs) has been done by sol-gel-hydrothermal colloidal route in two different apparatus; one being simple stainless steel (named as TiO2-B) and other being at constant temperature and pressure autoclave (named as TiO2-W). These TiO2 NPs were investigated by various characterization techniques such as scanning electron microscope (SEM), X-ray diffractometer (XRD), and photoluminescence spectrophotometer. Also, it was observed that the quality of the synthesized TiO2-W NPs is comparable with the commercial TiO2 NPs (TiO2-C), whereas the cost of synthesis is almost reduced to half. The synthesized TiO2 NPs are used as the photoanode in dye-sensitized solar cell (DSSC). DSSC with TiO2-W showed better power conversion efficiency as compared to DSSC with TiO2-B.

Preparation and Characterization of Submicron Star-Like ZnO as Light Scattering Centers for Combination with ZnO Nanoparticles for Dye-Sensitized Solar Cells

Submicron star-like ZnO (ZnO SZ) was synthesized via a facile hydrothermal method, and a series of composite photoanode materials with different ZnO SZ concentrations in the range from 0 wt.% to 0.20 wt.% were synthesized by a mechanical mixing method. The as-prepared samples were characterized by x-ray diffraction analysis, scanning electron microscopy, ultraviolet–visible (UV–Vis) absorption spectroscopy, etc. The results clearly showed that the mean diameter of the ZnO SZ was approximately 300 nm while its length was in the micrometer range, and the ZnO SZ was embedded homogeneously into the ZnO nanoparticle photoanode. Although UV–Vis spectral analysis revealed that increasing the ZnO SZ content decreased the dye adsorption density of the composite photoanode, the photocurrent density–voltage (J–V) characteristic indicated that dye-sensitized solar cells (DSSCs) using the ZnO SZ/ZnO composite photoelectrode exhibited significantly improved photovoltaic performance compared with those using pure ZnO nanoparticles. Electrochemical measurements revealed that DSSCs using 0.10 wt.% ZnO SZ showed improved efficiency of light energy conversion of 1.38%, being 43.75% higher than when using pure ZnO. All these results prove that incorporation of ZnO SZ into the ZnO nanoparticle photoelectrode represents a highly effective method for improving the photovoltaic properties of DSSCs.

First Principles Study on Structurally Resolved Titanium Dioxide Nanoparticles Functionalized by Organic Ligands

Titanium dioxide nanoparticles representing those in dye-sensitized solar cell photoanodes are modeled by first principles calculations, employing a series of structurally resolved polyoxometalates functionalized with organic ligands via the phosphonate anchoring group as a modeling platform. Previous computational studies on titanium dioxide nanoparticles for dye-sensitized solar cells and water splitting systems are based on artificial cleaving of TiO2 from bulk crystals, which introduces potential various human-made errors. This manuscript focuses on structurally resolved titanium dioxide nanoparticles determined from X-ray diffraction experiments with a 10−3 A resolution and demonstrates that charge transfer occurs from the organic ligands and oxygen atoms to the core titanium atoms. Also, different TiO2 nanoparticle geometries contribute to variation in the electronic and optical properties of the organic/TiO2 nanocomposite system. This computational work on structurally resolved molecularly functionalized titanium dioxide introduces a new way to model the TiO2 nanoparticle-based optoelectronic device, which eliminates the arbitrariness introduced during artificial cleaving and provides insights on the structure-property relationships of organic molecule-functionalized titanium dioxide nanoparticles for water splitting systems and dye-sensitized solar cells.

First principles study on structurally resolved titanium dioxide nanoparticles functionalized by organic ligands

Titanium dioxide nanoparticles representing those in dye-sensitized solar cell photoanodes are modeled by first principles calculations, employing a series of structurally resolved polyoxometalates functionalized with organic ligands via the phosphonate anchoring group as a modeling platform. Previous computational studies on titanium dioxide nanoparticles for dye-sensitized solar cells and water splitting systems are based on artificial cleaving of TiO2 from bulk crystals, which introduces potential various human-made errors. This manuscript focuses on structurally resolved titanium dioxide nanoparticles determined from X-ray diffraction experiments with a 10–3 Å resolution and demonstrates that charge transfer occurs from the organic ligands and oxygen atoms to the core titanium atoms. Also, different TiO2 nanoparticle geometries contribute to variation in the electronic and optical properties of the organic/TiO2 nanocomposite system. This computational work on structurally resolved molecularly functionalized titanium dioxide introduces a new way to model the TiO2 nanoparticle-based optoelectronic device, which eliminates the arbitrariness introduced during artificial cleaving and provides insights on the structure-property relationships of organic molecule-functionalized titanium dioxide nanoparticles for water splitting systems and dye-sensitized solar cells.

High-performance counter electrode of carbon nanocubes with embedded cobalt-iron alloy nanoparticles for dye-sensitized solar cells

High concentration of polyvinylpyrrolidone (PVP) favored the growth of cobalt hexacyanoferrate (CoHCF) nanocubes with sharp corners and small particle size during synthesis. The cobalt-iron (CoFe) alloy nanoparticles were embedded in the carbon matrix through pyrolysis of the CoHCF powder. The presence of PVP in CoHCF also changed the morphology and microstructure of the resultant carbon-CoFe composite. Bare CoHCF formed bamboo-like hollow nanotubes, while CoHCF nanoparticles capped with large and small amounts of PVP tended to form porous nanocubes and aggregated nanoparticles, respectively. Cyclic voltammetry and electrochemical impedance measurements indicated that the carbon-CoFe nanocube electrode exhibited better catalytic performance than the nanotube, nanoparticle, and Pt electrodes, mostly due to its higher surface area and suitable pore size distribution for facilitating the iodide/triiodide couple. Dye-sensitized solar cells (DSSCs) employing the nanocube counter electrode (CE) exhibited a high photovoltaic conversion efficiency of 9.20%, which was greater than those obtained using Pt (8.94%), nanotube (8.48%), and nanoparticle (8.40%) CEs. The enhanced performance of the DSSC using the nanocube CE was due to the low charge-transfer resistance of the porous nanocubes with embedded CoFe nanoparticles compared to the other CEs.

Composite Photoelectrode with TiO2 Nanofibers and Nanoparticles in Dye-Sensitized Solar Cells

Composite Photoelectrode with TiO₂ Nanofibers and Nanoparticles in Dye-Sensitized Solar Cells

Effect of calcination temperature on performance of ZnO nanoparticles for dye-sensitized solar cells

The photovoltaic performances of ZnO-based dye-sensitized solar cells (DSSCs) were studied using ZnO nanoparticles prepared via the sol–gel method in gelatin medium at different calcination temperatures. The effects of the calcination temperature on the size, surface area, photoluminescence properties, and dye adsorption ability of ZnO nanoparticles were investigated. The results showed that the size of the nanoparticles increased and the surface area decreased with an increase in the calcination temperature. In addition, the oxygen vacancies of the nanoparticles increased with an increase in the calcination temperature. Moreover, although the surface area of the nanoparticles prepared at 600°C was lower than that of those prepared at 500°C, their dye adsorption abilities were the same, and both were higher than that of those prepared at 700°C. Electrochemical impedance spectroscopy and open-circuit voltage decay measurements were carried out to investigate the cell functions. The DSSC based on ZnO nanoparticles calcined at 600°C exhibited the highest conversion efficiency because of its higher dye adsorption ability and lower recombination rate compared to the others.

Minimizing structural deformation of gold nanorods in plasmon-enhanced dye-sensitized solar cells

Plasmonic metal nanoparticles have shown great promise in enhancing the light absorption of organic dyes and thus improving the performance of dye-sensitized solar cells (DSSCs). However, as the plasmon resonance of spherical nanoparticles is limited to a single wavelength maximum (e.g., ~ 520 nm for Au nanoparticles), we have here utilized silica-coated gold nanorods (Au@SiO2 NRs) to improve the performance at higher wavelengths as well. By adjusting the aspect ratio of the Au@SiO2 NRs, we can shift their absorption maxima to better match the absorption spectrum of the utilized dye (here we targeted the 600–800 nm range). The main challenge in utilizing anisotropic nanoparticles in DSSCs is their deformation during the heating step required to sinter the mesoporous TiO2 photoanode and we show that the Au@SiO2 NRs start to deform already at temperatures as low as 200 °C. In order to circumvent this problem, we incorporated the Au@SiO2 NRs in a TiO2 nanoparticle suspension that does not need high sintering temperatures to produce a functional photoanode. With various characterization methods, we observed that adding the plasmonic particles also affected the structure of the produced films. Nonetheless, utilizing this low-temperature processing protocol, we were able to minimize the structural deformation of the gold nanorods and preserve their characteristic plasmon peaks. This allowed us to see a clear redshift of the maximum in the incident photon-to-current efficiency spectra of the plasmonic devices (Δλ ~ 14 nm), which further proves the great potential of utilizing Au@SiO2 NRs in DSSCs.

Preparation of plasmonic monolayer with Ag and Au nanoparticles for dye-sensitized solar cells

We fabricated a plasmonic layer by immobilizing both Au and Ag nanoparticles via P4VP on a photoactive layer for dye-sensitized solar cells (DSSCs) to prevent aggregation of metal nanoparticles, to increase absorbance of N719 dye, and to enhance light harvesting and power conversion efficiency (PCE). The optimal conditions for immobilizing these nanoparticles were also examined. With plasmonic Au and Ag nanoparticles, the PCE increased by 8.05% and 5.78%, respectively (plasmonic Au nanoparticles: from 8.82% to 9.53%; plasmonic Ag nanoparticles: from 8.82% to 9.33%). When both Au and Ag nanoparticles were employed in the plasmonic layer, the PCE showed further improvement of 10.17%, corresponding to a 15.31% enhancement. This significant improvement of the PCE could be explained by a broader range of light absorption resulting from the presence of the plasmonic layer.

Synthesis of new dyes containing double tetrazole groups for sensitization of TiO2 nanoparticles in dye-sensitized solar cells

Di(1H-tetrazol-5-yl)methane is employed as a new electron acceptor group in the synthesis of two metal-free organic dyes containing triphenylamine donor group. Dye-sensitized nanocrystalline TiO2 solar cell (DSSC) applying these novel dyes is constructed for consideration of their photovoltaic properties. The electronic properties of the dyes are also considered with the aid of theoretical calculations. The DSSC constructed from 4-(2,2-di(1H-tetrazol-5-yl)vinyl)-N,N-diphenylaniline (T1) shows a short-circuit photocurrent density of 13.38 mA cm−2, an open circuit voltage of 578 mV, and a fill factor of 0.54, with a resulted solar energy-to-electricity conversion efficiency of 4.18% under simulated 1 sun irradiation (100 mW cm−2). This result reveals that the dye with the di(1H-tetrazol-5-yl)methane anchoring group injects more electrons to the conduction band of TiO2 in comparison with its analogs with single tetrazole ring in their anchoring group. It is found that in spite of a red-shift of the absorption spectrum resulted from the lengthening of the molecule, the dye with two di(1H-tetrazol-5-yl)methane groups gives lower performance than the dye with a single electron acceptor.

Fabrication of dye-sensitized solar cells using a both-ends-opened TiO 2 nanotube/nanoparticle hetero-nanostructure

Abstract We fabricated a hetero-structure photoanode with both-ends-opened TiO2 nanotubes and TiO2 nanoparticles for dye-sensitized solar cells (DSSCs). Two-step anodization and selective etching process were used to obtain the both-ends-opened TiO2 nanotubes. A heat treatment was employed to obtain anatase crystal-structured nanotubes. The effect of the both-ends-opened TiO2 nanotubes on the photoelectric conversion efficiency (PCE) of the DSSCs was evaluated by positioning the TiO2 nanotubes on TiO2 nanoparticle layers and by sandwiching them between the TiO2 nanoparticles. It is suggested that both-ends-opened TiO2 nanotubes serve as incident light scattering layers that lead to superior light harvesting efficiency of DSSCs. This increases the electron lifetime and results in the recycling of more light by dye molecules, thus increasing the photocurrent density. Consequently, a high PCE of 7.74% was obtained when the TiO2 nanotubes were placed on the TiO2 nanoparticles and a PCE of 8.56% was obtained when the TiO2 nanotubes were placed between the TiO2 nanoparticles.

Double-layered TiO2 anodes from nanorods and nanoparticles for dye-sensitized solar cells

Double-layered TiO2 photoanodes consisting of bottom nanoparticles and top nanorods are synthesized for dye-sensitized solar cells (DSSCs). The cell performances can be maximized by optimizing the thickness of TiO2 nanoparticle layer, and the preliminary results demonstrate that a promising power conversion efficiency of 8.66% is determined on the device with 10µm-TiO2 nanoparticles/nanorods anode, yielding an 30.2% enhancement in cell efficiency in comparison to pristine TiO2 nanoparticle based solar cell.

High-performance and transparent counter electrodes based on polypyrrole and ferrous sulfide nanoparticles for dye-sensitized solar cells

The polypyrrole (PPy) electrode is synthesized by chemical oxidative polymerization on fluorine-doped tin oxide glass. Then the ferrous sulfide (FeS) nanoparticles is formed during the PPy nanoparticles by immersing the PPy electrodes in fresh Na2S methanol solution (0.1 M) for 20 min. The synergistic effect of PPy and FeS nanoparticles make PPy/FeS CE possesses perfect transparency, good conductivity and excellent electrocatalytic activity for the reduction of triiodide/iodide. This would be attributed to improve the contact between counter electrode and electrolyte and enhance the collection and transmission of electrons. The transparent and high-efficiency PPy/FeS CE appears to be a potential candidate to the high cost and corrodible Pt CE of DSSCs. The dye-sensitized solar cells (DSSCs) based on PPy/FeS electrode can obtain a higher power conversion efficiency (PCE) of 7.48 % than that of DSSCs with pure PPy electrode (6.45 %) or Pt electrode (7.10 %) under full sunlight illumination (100 mW cm−2, AM 1.5 G). Furthermore, the DSSC based on PPy/FeS electrode would obtain a high value of PCE (5.72 %) with back illumination.

Photovoltaic Effect of Metal-Doped TiO2 Nanoparticles for Dye-Sensitized Solar Cells

Crystalline anatase TiO2 nanoparticles (NPs) synthesized by a sol-gel method were used as photoelectrodes in dye-sensitized solar cells (DSSCs). In order to improve the electrochemical properties such as the open circuit voltage (Voc) and the rate of electron transfer, various amounts of Al and Zn were doped into TiO2 NPs. Al doping of TiO2 NPs successfully improved the photovoltaic performance of the DSSCs as seen in the Voc of 0.79 V for these electrodes. The Zn-doped TiO2 NPs exhibited faster electron transport than pure TiO2 or Al-doped TiO2 NPs. The photovoltaic efficiency (η) of pure TiO2 NPs, 4 mmol Al-doped TiO2 NPs, and 3 mmol Zn-doped TiO2 NPs-based DSSCs are 3.90, 5.86, and 5.58%, respectively. In order to improve the Voc, Jsc, and electron transfer rates simultaneously, the 4 mmol Al-doped TiO2 NP and 3 mmol Zn-doped TiO2 NP powders were mixed together and used for the preparation of photoelectrodes. The η of the mixed Al/Zn-doped TiO2 NPs-based DSSC was 7.12%, while the Voc, Jsc, and electron transport times were 0.75 V, 14.38 mA cm−2 and 3.112 × 10−4 s, respectively.