Dye-sensitized solar cells using ZnO nanotips and Ga-doped ZnO films (original) (raw)
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Influence of morphology on the performance of ZnO-based dye-sensitized solar cells
ZnO nanomaterials with different morphologies, obtained by a sonochemical synthesis method at pH values of 5.5, 8, 10 and 12, have been used as starting materials for the fabrication of dye-sensitized solar cells. The morphology of the nanomaterials and the texture of the films deposited using screen printing depend on the synthesis pH, and the various exposed surface facets interact in a different manner with the dye and electrolyte solutions. The best cell performance was obtained with the morphology that resulted from the synthesis at pH 10, where the {100} and {110} crystal forms are predominant, and where dye coverage was largest. Interestingly, the BET total surface area was lowest for this nanomaterial illustrating the importance of morphology. The influence of the synthesis pH was also evident in the energetics and recombination kinetics of the solar cells. For the ZnO material synthesized at pH 5.5, the band edges appear to be shifted to more negative potentials, which could have resulted in a larger open circuit potential based on thermodynamic considerations. However, the electron life time for the pH 5.5 ZnO material is significantly smaller than for the other three synthesis pH values, indicating that the recombination kinetics are significantly faster for these cells as well, resulting in a smaller open circuit potential based on kinetics arguments. The balance between these two effects determines the experimentally observed open circuit potential. Overall, the results indicate that the dependence of the dye adsorption characteristics on ZnO nanomaterial morphology and film texture are the dominating factors that determine the solar cell performance.
Scientific Review Dye Sensitized Solar Cells Incorporated with Tio 2-ZnO Nanoparticles
2017
The escalated and savage consumption of conventional sources of energy are leading to forecasted energy and environmental crises [1]. Solar Energy emerged as feasible alternative to confront the major environmental problems that result from the uncontrolled use of fossil resource in energy generation because "More energy from sunlight strikes Earth in 1 hour than all of the energy consumed by humans in an entire year" [2]. In 1991, Professor Grätzel reported a new low cost chemical solar cell by the successful combination of nanostructured electrode and efficient charge injecting dye, known as Grätzel cell or dye-sensitized solar cell which falls under the third generation photovoltaic cells [3]. In dye sensitized solar cells (DSSCs), dye molecules adsorbed on the oxide play a role of ""antenna"" for photon capturing. For this reason, accompanying with the development of DSSCs, organic dyes have been intensively studied with a focus on increasing the extinction coefficient and extending the optical absorption spectrum [4-10]. However, a major problem confronting these cells is the low efficiency of conversion. In optimizing the device performance and stability of DSSC, several research efforts have been expended on manipulating the corresponding architecture involving inorganic and organic systems as well as various interfaces so as to enhance the cell performance [11-14]. In general, ZnO nanoparticles based DSSCs shows low photoelectrochemical performance as compared to commercial TiO 2 based DSSCs [15]. Some of the limiting factor for this is insufficient attachment of dyes with the nanoparticles, formation of aggregation between the nanoparticles up on film formation, low injection rate, low regeneration of electron, and formation of Zn 2+ /dye complex. The formation of Zn 2+ /dye complex can agglomerate which comes from dissolution of the nanostructured film to form a thick covering layer instead of a monolayer, and is therefore inactive for electron injection which also limit the cell performance. This study proposed simple design strategies for realizing how to improve photovoltaic properties of the cell by coating on top of a TiO 2 semiconductor a layer of ZnO with different thickness. The PV performance of the formed DSSCs were investigated systematically. The conversion efficiency was increased from 0.0030 % to 0.0064 % for DSSC with 2 SILAR cycles which produces the best performance.
Dependence of ZnO-based dye-sensitized solar cell characteristics on the layer deposition method
Bulletin of Materials Science, 2015
The selection of a proper method for the semiconductor layer deposition is an important requirement towards a high efficiency for dye-sensitized solar cells (DSSCs). We compared three techniques for deposition of the semiconductor thin layer in ZnO-based DSSCs, in order to determine the dependence between the deposition method, the ZnO film properties and finally the DSSCs characteristics. For this purpose, we varied the method used for deposition of the semiconductor film and we replaced ZnO with Al-doped ZnO. The nanostructured films morphology was analysed by transmission electron microscopy, high-resolution transmission electron microscopy and selected area electron diffraction. The optical properties were examined by UV-visible spectroscopy and the bandgap energies were calculated using the Tauc equation. The higher fill factor value was registered for DSSCs based on the ZnO film obtained by electrochemical method, but the higher efficiency was registered for doctorblading method.
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.
ZnO Nanostructures for Dye-Sensitized Solar Cells
Advanced Materials, 2009
This Review focuses on recent developments in the use of ZnO nanostructures for dye-sensitized solar cell (DSC) applications. It is shown that carefully designed and fabricated nanostructured ZnO films are advantageous for use as a DSC photoelectrode as they offer larger surface areas than bulk film material, direct electron pathways, or effective light-scattering centers, and, when combined with TiO 2 , produce a core-shell structure that reduces the combination rate. The limitations of ZnO-based DSCs are also discussed and several possible methods are proposed so as to expand the knowledge of ZnO to TiO 2 , motivating further improvement in the power-conversion efficiency of DSCs.
Dye sensitized solar cell (DSSC) is a promising candidate for a low cost solar harvesting technology as it promised a low manufacturing cost, ease of fabrication and reasonable conversion efficiency. Basic structure of DSSC consists of photoanode, dye, electrolyte and counter electrode. Photoanode plays an important role for a DSSC as it supports the dye molecules and helps in the electron transfer that will determine the energy conversion efficiency. This paper emphasizes the various improvements that had been done on the TiO2 and ZnO photoanode nanostructures synthesized through thermal method. For overall comparisons, ZnO nanoflowers photoanode had achieved the highest energy conversion efficiency of 4.7% due to its ability of internal light scattering that had increased the electron transportation rate. This has made ZnO as a potential candidate to replace TiO2 as a photoanode material in DSSC.
Energies
In this research article, the authors have discussed the simulation, analysis, and characterization of calcium-doped zinc oxide (Ca-doped-ZnO) nanostructures for advanced generation solar cells. A comparative study has been performed to envisage the effect of Ca-doped ZnO nanoparticles (NP), seeded Ca-doped ZnO nanorods (NR), and unseeded Ca-doped ZnO NR as photoanodes in dye-sensitized solar cells. Simulations were performed in MATLAB fuzzy logic controller to study the effect of various structures on the overall solar cell efficiency. The simulation results show an error of less than 1% in between the simulated and calculated values. This work shows that the diameter of the seeded Ca-doped ZnO NR is greater than that of the unseeded Ca-doped ZnO NR. The incorporation of Ca in the ZnO nanostructure is confirmed using XRD graphs and an EDX spectrum. The optical band gap of the seeded substrate is 3.18 eV, which is higher compared to those of unseeded Ca-doped ZnO NR and Ca-doped ZnO...
Effect of Growth Temperature on ZnO Nanorod Properties and Dye Sensitized Solar Cell Performance
Nanostructure of semiconductor materials zinc oxide (ZnO) is widely used in fabrication of solar cell devices. The performance of such devices is strongly depending on the nanostructures of the thin films used. In this paper reports the effect of growth temperature during synthesis of one-dimensional (1-D) anatase ZnO nanorod arrays through hydrothermal process facing their structure, morphology, and optical properties. The ZnO nanorod was first synthesized use the solution concentration and time fixed at 0.04M and 1 hour. The growth temperature were varied from 70, 80, 90 and 100 ∘ C. The effect of growth temperature on the structural, morphology, and optical absorption of ZnO nanorod were studied by using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and UV–vis spectroscopy. The regularity, diameters, heights, and surface densities of the ZnO nanorods were increased with the growth temperature.The optimum results of FESEM characterizations showed that the grown ZnO nanorods have diameters of 64.14 ± 8.3 nm, heights of 363.72 ± 34 nm and surface densities of 182 numbers/í µí¼m 2 which was obtained at temperature of 90 ∘ C. The optimum ZnO nanorod film was utilized as photo anode in dye sensitized solar cells. The DSSC yielded Jsc of 0.86 mA/cm 2 , Voc of 0.49 V, and FF of 38 %, resulting in PCE of 0.16 %.
ZnO and TiO2 Nanostructured Dye sensitized Solar Photovoltaic Cell
Materials Today: Proceedings, 2019
The performance of nanostructured metal oxides (ZnO and TiO 2) based dye sensitized solar cells (DSSC) were investigated. Natural dye, chlorophyll extracted from fresh spinach leaves, was used as sensitizer for fabrication of the cells. ZnO was synthesized by chemical bath deposition technique.The Field emission scanning electron microscopic (FESEM) images show hexagonal patterned ZnO nano-towers of 5 µm length and ~ 1 µm diameter. TiO 2 was synthesized by sol-gel method.The FESEM images show that the TiO 2 nano-rods of 2 µm length and ~ 300 nm diameter.TiO 2 based DSSC was possessed better efficiency of 0.27% as compare to ZnO based DSSC of 0.13%.