Enhanced conversion efficiency of quasi solid state dye sensitized solar cells based on functionalized multi-walled carbon nanotubes incorporated TiO<Subscript>2</Subscript> photoanode

A series of quasi solid state dye sensitized solar cells were fabricated based on the different weight% of MWCNT@TiO₂ photoanode. The MWCNT@TiO₂ nanocomposites were synthesized by simple wet impregation method. The incorporation of MWCNT into the TiO₂ was confirmed by X-ray diffraction, energy dispersive X-ray spectrum and UV–visible spectroscopy. The morphological properties of the nanocomposites were analyzed by transmission electron microscopic analysis. The performance of the quasi solid state dye sensitized solar cell depends solely on the MWCNT content of the photoanode, as the same PVA polymer gel electrolyte has been used. Compared to the conventional TiO₂ photoanode based DSSCs 0.05 wt% MWCNT containing photoanode provide the maximum short circuit current density and the photo conversion efficiency of 9.811 mA/cm^?2 and 3.59 %. The introduction of MWCNT into the TiO₂ results in the rapid electron transport in the photoanode by forming a conductive network due to which improvement in the short circuit current was observed.     

种子层对染料敏化ZnO纳米棒光伏电池性能的影响

用射频溅射法在透明导电玻璃上分别沉积了氧化锌（ZnO）和掺铝氧化锌（AZO）薄膜，其可见光透射率达到85％以上。用水热法在不同的薄膜作种子层的导电玻璃上生长了纳米棒，x射线衍射分析（XRD）发现所制得的纳米棒都有（002）择优取向；扫描电子显微镜（SEM）结果表明，采用不同的实验条件和参数可以有效的影响纳米棒的长度、直径、密度等，并得到了垂直于衬底的纳米结构。用所得到的纳米结构制作太阳能电池的效率达到了0．26％。     

Study on CaCO3-coated ZnO nanoparticles based dye sensitized solar cell

Dye sensitized solar cells (DSSCs) have been fabricated using ZnO and CaCO₃-coated ZnO nanoparticles. The effect of CaCO₃ coating on the performance of DSSC has been investigated. CaCO₃-coated ZnO nanoparticles have been synthesized by hydrothermal method. X-ray diffraction patterns of synthesized nanoparticles reveal that the ZnO and CaCO₃-coated ZnO nanoparticles have respectively wurtzite and rhomb-centred structure and both having hexagonal phase. Transmission electron microscopy study reveal that ZnO and CaCO₃-coated ZnO nanoparticles possess spherical symmetry and have average particle size respectively 6.2 and 6.7 nm. In case of CaCO₃/ZnO nanoparticles, the quenching in photoluminescence emission intensity has been attributed to the decrease in recombination rate of photo-generated electron–hole pairs. UV–Vis absorption spectra, confirms that the electrodes fabricated from the CaCO₃-coated ZnO nanoparticles have higher absorbance that shows their higher dye adsorbing power. The use of CaCO₃ coating has been found to enhance the efficiency of DSSC by over 100 %.     

TiO2 thin film encapsulated ZnO nanorod and nanoflower dye sensitized solar cells

The performance of dye-sensitized solar cells based on ZnO nanorods and nanoflowers coated with thin shells of TiO₂ thin film prepared by sol–gel deposition are described. It is found that shells act as insulating barriers that improve cell open-circuit voltage and short-circuit current density. The superior performance of the ZnO–TiO₂ core–shell cells is a result of a radial electron transport within each ZnO nanorods and nanoflowers that decreases the rate of recombination and percolation of the electron in these devices.     

Hydrothermal synthesis of titanate nanoparticle/carbon nanotube hybridized material for dye sensitized solar cell application

With the hydrothermal treatment, titanate nanostructure with distinctively different morphology and surface characteristics was successfully synthesized from commercial rutile titania powder dispersed in accommodating media which were deionized water or NaOH solution. Hybridized materials of titanate nanoparticles and carbon nanotubes (CNT) were also synthesized by the hydrothermal treatment process. Intrinsic interaction of titanate nanoparticles and CNTs could be confirmed by spectroscopic analysis. The synthesized titanate nanoparticle/CNT hybridized material was then employed for fabricating a working electrode of dye-sensitized solar cells (DSSC). Based on experimental results, DSSC fabricated from the hybridized titanate nanoparticles and carbon nanotubes could provide the highest photoconversion efficiency of approximately 3.92%.     

Investigation on effect of blocking layer in perovskite sensitized pure and aluminium doped ZnO photoanode solar cell

ZnO is a promising candidate as low cost, porous semiconductor material for photoanodes in a dye sensitized solar cell. In this work, we investigate the performance of pure ZnO nanoparticles (ZNPs), Al₂O₃ doped ZnO (Al@ZNPs) and ZnO/Nb₂O₅ core–shell structure of photoanode material. These electrodes were sensitized with a pervoskite CH₃NH₃SnCl₃ sensitizer. To study the effect of the Al₂O₃, Nb₂O₅ treatment with ZnO, the J–V and EIS parameters, the current density (Jsc),Open circuit voltage (Voc), fill factor (FF), electron life time (τ_n), electron mobility (µ) and charge collection efficiency (?_cc) are calculated for the fabricated solar cells and the results are compared. It was found that the Al₂O₃ doped ZnO with the sensitizer CH₃NH₃Sncl₂ showed the highest efficiency of 9.41% under 100 mW/cm² irradiation. The electron impedance spectroscopy revealed that the charge collection efficiency (?_cc) of the solar cells is in the order of PSSC3?>?PSSC4?>?PSSC2?>?PSSC1. In this work, the effect of blocking layer (Ta₂O₅) is also discussed. From the J–V and EIS analysis, the effect of blocking layer is appreciable and it is useful to increase the efficiency of the solar cell by the way of reducing the recombination of charge carriers process. Therefore, the increase of photocurrent is mainly due to the combined effect of the sensitizer competence and blocking layer.     

Surfactant mediated growth of ZnO nanostructures and their dye sensitized solar cell properties

Single crystalline and highly aligned ZnO nanorods, faceted microrods, nanoneedles and nanotowers were grown onto glass substrates by a facile aqueous chemical method at relatively low temperature (90 °C). Various structure directing agents or organic surfactants such as diaminopropane (DAP), polyacrylic acid (PAA) and polyethylenimine (PEI) were used to modify the surface morphology. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and optical absorption. It was found that, vertically aligned ZnO nanorods formation takes place with preferential orientation along (002) plane. The organic surfactants play an important role in modifying the morphology. The samples were further used to fabricate dye sensitized solar cells. The highest photocurrent (670 μA) and efficiency were observed for the ZnO:PEI sample.     

Fabrication of dye sensitized solar cell using TiO2 coated carbon nanotubes

We fabricated a dye sensitized solar cells (DSCs) using TiO₂ coated multi-wall carbon nanotubes (TiO₂-CNTs). Carbon nanotubes (CNTs) have excellent electrical conductivity and good chemical stability. We introduced CNTs in DSCs to improve solar cell performance through reduction of series resistance. TiO₂-CNTs were obtained by Sol-Gel method. Compared with a conventional TiO₂ cell, the TiO₂-CNTs content (0.1 wt.%) cell showed ∼ 50% increase in conversion efficiency, which is attributed to the increase in short circuit current density (J_sc). The enhancement in J_sc occurs due to improvement in interconnectivity between the TiO₂ particles and the TiO₂-CNTs in the porous TiO₂ film.     

Dye sensitized solar cells using freestanding TiO2 nanotube arrays on FTO substrate as photoanode

The front-side illuminated dye-sensitized solar cells with TiO₂ nanotube arrays/FTO based photoanode were fabricated by a simple detachment and transfer method. The morphology and crystalline phase of the TiO₂ nanotubes were studied by scanning electron microscopy and X-ray diffraction. A photoconversion efficiency of 1.78% was obtained using TiO₂-nanotube/FTO glass as a photoanode. It was found that the average tubes diameter increased with anodizing voltage, and higher photoconversion efficiency was obtained for nanotubes synthesized at the higher voltage.     

The effects of anodization parameters on titania nanotube arrays and dye sensitized solar cells

Ordered, closely packed, and vertically oriented titania nanotube arrays with lengths exceeding 10?μm were fabricated by anodization of titanium foils. The effects of anodization voltage and time on the microstructural morphology and the photovoltaic performance of dye sensitized solar cells based on the titania nanotube arrays were investigated. On increasing the anodization voltage or time, the increase in active surface area leads to enhanced photovoltaic currents and thereby an overall higher performance of the dye sensitized solar cells. The efficiency enhancement with rising anodization voltage exceeds the increase in the outer surface area of the nanotubes, indicating that the active surface area is further enlarged by a more accessible inner surface of the nanotube arrays grown with a higher anodization voltage. A promising efficiency of 3.67% for dye sensitized solar cells based on anodized titania nanotube arrays was achieved under AM1.5, 100?mW?cm(-2) illumination.     

A hybrid PVDF-HFP/nanoparticle gel electrolyte for dye-sensitized solar cell applications

Graphite and TiO(2) nanoparticles are used as fillers to prepare a polymer gel electrolyte (PGE) based on I(-)/I(3)(-) and poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) for dye-sensitized solar cell (DSSC) applications. Graphite nanoparticles (GNP) were proved to be a more efficient filler than TiO(2) in enhancing the charge conductivity of the PGE, decreasing the activation energy for charge transport and inhibiting the charge recombination at the TiO(2)/electrolyte interface. The energy conversion efficiency of a DSSC fabricated using a PGE containing 0.25?wt% of GNP can be increased from 4.69% (without filler) to 6.04%, close to that of a liquid system obtained in this work.     

Effect of TiO2 nanotube length and lateral tubular spacing on photovoltaic properties of back illuminated dye sensitized solar cell

The main objective of this study is to show the effect of TiO₂ nanotube length, diameter and intertubular lateral spacings on the performance of back illuminated dye sensitized solar cells (DSSCs). The present study shows that processing short TiO₂ nanotubes with good lateral spacings could significantly improve the performance of back illuminated DSSCs. Vertically aligned, uniform sized diameter TiO₂ nanotube arrays of different tube lengths have been fabricated on Ti plates by a controlled anodization technique at different times of 24, 36, 48 and 72?h using ethylene glycol and ammonium fluoride as an electrolyte medium. Scanning electron microscopy (SEM) showed formation of nanotube arrays spread uniformly over a large area. X-ray diffraction (XRD) of TiO₂ nanotube layer revealed the presence of crystalline anatase phases. By employing the TiO₂ nanotube array anodized at 24?h showing a diameter ??80?nm and length ??1·5???m as the photo-anode for back illuminated DSSCs, a full-sun conversion efficiency (??) of 3·5 % was achieved, the highest value reported for this length of nanotubes.     

Comparison of dye solar cell counter electrodes based on different carbon nanostructures

Three characteristically different carbon nanomaterials were compared and analyzed as platinum-free counter electrodes for dye solar cells: 1) single-walled carbon nanotube (SWCNT) random network films on glass, 2) aligned multi-walled carbon nanotube (MWCNT) forest films on Inconel steel and quartz, and 3) pressed carbon nanoparticle composite films on indium tin oxide-polyethylene terephtalate plastic. Results from electrochemical impedance spectroscopy and electron microscopy were discussed in terms of the catalytic activity, conductivity, thickness, transparency and flexibility of the electrode films. The SWCNT films showed reasonable catalytic performance at similar series resistance compared to platinized fluorine doped tin oxide-coated glass. The MWCNTs had similar catalytic activity, but the electrochemical performance of the films was limited by their high porosity. Carbon nanoparticle films had the lowest charge transfer resistance resulting from a combination of high catalytic activity and dense packing of the material.     

Comparison between synthesis techniques to obtain ZnO nanorods and its effect on dye sensitized solar cells

This paper reports additive-free, reproducible, low-temperature solution-based process for the preparation of crystalline ZnO nanorods by homogeneous precipitation from zinc acetate. Also, ZnO nanorod structured dye sensitized solar cells using ruthenium dye (Z907) have been fabricated and characterized. The formation and growth of zinc oxide nanorods are successfully achieved. We analyzed three different synthesis method using solution phase, autoclave and microwave. The calcination effects on the morphology of ZnO nanorods are also investigated. Analysis of ZnO nanorods shows that calcination at lower temperature is resulted in a nanorod growth. Additive-free, well-aligned ZnO nanorods are obtained with the length of 330–558 nm and diameters of 14–36 nm. The XRD, SEM, and PL spectra have been provided for the characterization of ZnO nanorods. Microwave-assisted ZnO nanostructured dye sensitized solar cell devices yielded a short-circuit photocurrent density of 6.60 mA/cm², an open-circuit voltage of 600 mV, and a fill factor of 0.59, corresponding to an overall conversion efficiency of 2.35% under standard AM 1.5 sun light.     

A novel gel polymer electrolyte based on polyacrylonitrile (PAN) and its application in a solar cell

A PAN-based gel polymer electrolyte with possible iodide ion conductivity was prepared by incorporating a mixture of Pr₄N⁺I⁻, iodine, EC and PC in PAN. Out of various compositions prepared and characterised, the sample with composition PAN (13%):EC (31%):PC (45%):Pr₄N⁺I⁻ (7%):I₂ (4%) by weight ratio, exhibited the maximum room temperature (25°C) conductivity of 2.95×10⁻³ S cm⁻¹. The predominantly ionic nature of the electrolyte was established by using the dc polarisation technique. The temperature dependence of ionic conductivity follows the VTF behaviour, indicating the amorphous nature of the electrolyte. Dye-sensitised photoelectrochemical solar cells prepared using this electrolyte exhibited an open circuit voltage (V_oc) of 0.69 V, a short circuit current (I_sc) of 3.73 mA cm⁻² for an incident light intensity of 600 W m⁻² yielding an overall quantum efficiency of 2.99%.     

A structural supercapacitor based on activated carbon fabric and a solid electrolyte

ABSTRACT

This paper presents investigations to create a structural supercapacitor with activated carbon fabric electrodes and a solid composite electrolyte, consisting of organic liquid electrolyte 1?M TEABF₄ in propylene carbonate and an epoxy matrix where different compositions were considered of 1:2, 1:1 and 2:1 w/w epoxy:liquid electrolyte. Vacuum-assisted resin transfer moulding was used for the impregnation of the electrolyte mixture into the electrochemical double layer capacitor (EDLC) assembly. The best electrochemical performance was exhibited by the 1:2 w/w epoxy: liquid electrolyte ratio, with a cell equivalent-in-series resistance of 160?Ω?cm² and a maximum electrode-specific capacitance of 101.6?mF?g^?1 while the flexural modulus and strength were 0.3?GPa and 29.1?MPa, respectively, indicating a solid EDLC device.     

Dye modification with photovoltaic enhancement for CdS quantum dots sensitized solar cell based on three-dimensional ZnO spheres

A large amount of ZnO with a three-dimensional sphere-like morphology has been synthesized by a facile hydrothermal route and applied as the photoanode material in CdS quantum dots sensitized solar cells (QDSSCs). After the modification of the dye co-sensitized process, an overall power conversion efficiency of 2.32 % with a short-circuit current density of 9.25 mA/cm² was obtained in ZnO/CdS/dye-QDSSC, which shows 66.9 and 49.4 % respective improvement over that of pure ZnO/CdS–QDSSC. This result is attributed to its superiority in light absorption and charge–hole separation for the ZnO/CdS/dye-QDSSC.     

A solid-state dye-sensitized solar cell based on a novel ionic liquid gel and ZnO nanoparticles on a flexible polymer substrate

This paper describes a new strategy to make a full solid-state, flexible, dye-sensitized solar cell (DSSC) based on novel ionic liquid gel, organic dye, ZnO nanoparticles and carbon nanotube (CNT) thin film stamped onto a polyethylene terephthalate (PET) substrate. The CNTs serve both as the charge collector and as scaffolds for the growth of ZnO nanoparticles, where the black dye molecules are anchored. It opens up the possibility of developing a continuous roll to roll processing for THE mass production of DSSCs.