Low temperature carving of ZnO nanorods into nanotubes for dye-sensitized solar cell application (original) (raw)
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ZnO Nanorods Formation for Dye-Sensitized Solar Cells Applications
International Journal of Technology, 2017
Different morphologies of zinc oxide (ZnO) can be obtained through various synthesizing methods, such as that of the water bath. By synthesizing under various conditions, different ZnO morphologies can be seen as the result of the water bath method. Replacing ZnO nanoparticles with vertically aligned ZnO nanorods results in a much higher energy conversion efficiency. Yet vertically aligned nanorods can only be grown through difficult and expensive methods. Several researchers have studied the growth of one-dimensional (1D) nanorods on homogeneous film with various growth conditions. However, there has been little in the way of research on ZnO nanorods grown on ZnO seed layers using the water bath method. In this research, vertically aligned nanorods with an optimum size ratio were formed through a simple water bath method. This method reveals that the ZnO nanorods are well aligned and grown with a high density and uniformity on the substrate. Their X-ray diffraction patterns reveal that the nanorods are grow in the [001] direction. The density, diameter, and length of the ZnO nanorods can be altered by changing the growing condition. All of the samples were characterized using a scanning electron microscope, X-ray diffraction, and micro Raman spectroscopy. To investigate crystal growth, zinc nitrate and zinc acetate were used when preparing the solution. The results demonstrate that the morphology and alignment of ZnO nanorods are determined by the precursor's type and deposition time.
Journal of Materials Science: Materials in Electronics, 2015
The effect of hexamethylenetetramine (HMT) concentration while keeping zinc nitrate [Zn(NO 3) 2 ] at constant concentration and vice versa on the morphology, optical absorption, structure of ZnO nanostructure and the performance of the DSSC utilizing the ZnO samples has been investigated. The ZnO photoanode samples were deposited on FTO substrate via hydrothermal growth at 90°C for 8 h followed by cooling at 50°C for 16 h. It was found that the structure and morphology of ZnO nanostructure are significantly influenced by the molar ratio of precursor concentration. The high density and smaller diameter of ZnO nanorods were formed when molar ratio of OHion concentration was increased. The modification on the shape and porosity of ZnO nanostructure are seemingly influenced by the amount of free ion Zn ?2 in the growth solution. The samples have been utilized as photoanode in DSSC. The DSSC utilizing ZnO nanosheets performs the J SC , V OC , FF and g of 3.6 mA cm-2 , 0.50 V, 0.31 and 0.56 %, respectively. The highest performance of that cell is due to the high density and unique morphology of ZnO nanosheets that offered high specific surface area for higher dye loading and light harvesting.
Effects of Na-doping on the efficiency of ZnO nanorods-based dye sensitized solar cells
Journal of Materials Science: Materials in Electronics, 2014
Na-doped ZnO nanorods (Zn 1-x Na x O: x = 0.0, 0.02, 0.04) were grown by a chemical bath deposition method on ZnO seeded FTO substrates. The influence of Na-doping on the efficiency of ZnO nanorods-based dye-sensitized solar cells (DSSCs) was investigated. Undoped and Na-doped ZnO nanorods were used as photo-anodes for the fabricated DSSCs. X-ray diffraction measurements exhibited that all the samples had a wurtzite structure of ZnO with a preferred orientation of (002) plane. Scanning electron microscopy images of the samples revealed that all the samples displayed hexagonal shaped nanorods. It was observed from optical measurements that the band gap energy gradually decreased from 3.29 to 3.21 eV for undoped and 4 at.% Na-doped ZnO nanorods, respectively. Photoluminescence spectrum for undoped ZnO showed three peaks located at 379, 422, and 585 nm corresponding to UV emission, zinc vacancy, and deep level emission (DLE) peaks, respectively. When ZnO nanorods were doped with 2 at.% Na, the intensity of UV peak increased whereas the intensity of DLE peak decreased. The maximum conversion efficiency of DSSCs was found to be 0.22 % with a J sc of 0.80 mA/cm 2 , V oc of 0.49 V, and fill factor of 0.523 as ZnO nanorods were doped with 2 at.% Na atoms.
ZnO Nanotube Based Dye-Sensitized Solar Cells
Nano Letters, 2007
Atomic layer deposition is utilized to coat pores conformally, providing a direct path for charge collection over tens of micrometers thickness. Compared to similar ZnO-based devices, ZnO nanotube cells show exceptional photovoltage and fill factors, in addition to power efficiencies up to 1.6%. The novel fabrication technique provides a facile, metal-oxide general route to well-defined DSSC photoanodes.
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 %.
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.
Nanoscale Research Letters, 2012
A low-temperature, direct blending procedure was used to prepare composite films consisting of zinc oxide [ZnO] nanoparticles and multiwalled carbon nanotubes [MWNTs]. The mesoporous ZnO/MWNT films were fabricated into the working electrodes of dye-sensitized solar cells [DSSCs]. The pristine MWNTs were modified by an air oxidation or a mixed acid oxidation treatment before use. The mixed acid treatment resulted in the disentanglement of MWNTs and facilitated the dispersion of MWNTs in the ZnO matrix. The effects of surface property and loading of MWNTs on DSSC performance were investigated. The performance of DSSCs was found to depend greatly on the type and the amount of MWNTs incorporated. At a loading of 0.01 wt%, the acid-treated MWNTs were able to increase the power conversion efficiency of fabricated cells from 2.11% (without MWNTs) to 2.70%.
Dye-Sensitized Solar Cells (DSSC) Based on ZnO Non-and Vertically Aligned Nanorod Structures
DSSCs performance can be enhanced by modifying the morphology of photoelectrode. Apart from titanium dioxide, TiO 2 ,the widely used oxide semiconductors for DSSC photoelectrode,ZnO-based DSSC is interesting to be developed due to its higher position of the conduction band compared to that of TiO 2 allowing possibility to generate higher photovoltage. In this study, ZnO-based DSSCs were fabricated by employing non-and vertically aligned nanorod. They were synthesized by co-precipitation method using precursor of ZnAc dihydrate. ZnO based DSSCs were sensitized with anthocyanin natural dye extracted from mangosteen pericarp and Ru-based dye (N719).As expected, the efficiencies of ZnO non-vertically aligned in natural dye were less than that of ZnO vertically aligned in N719 dye. Faster electron transport in ZnO vertically aligned structure could minimize the electron recombination rate which reduces the photocurrent. However, both structures showed that the annealing the photoelectrode at temperatures of 250-300 o C could generate higher conversion efficiency.Higher annealing temperature may lead to a higher ZnO crystallinity and further increases the open circuit photovoltage.
Micromachines
This paper reports on the synthesis of ZnO nanowires (NWs), as well asthe compound nanostructures of nanoparticles (NPs) and nanowires (NWs+NPs) with different coating layers of NPs on the top of NWs and their integration in dye-sensitized solar cells (DSSCs). In compound nanostructures, NWs offer direct electrical pathways for fast electron transfer, and the NPs of ZnOdispread and fill the interstices between the NWs of ZnO, offering a huge surface area for enough dye anchoring and promoting light harvesting. A significant photocurrent density of 2.64 mA/cm2 and energy conversion efficiency of 1.43% was obtained with NWs-based DSSCs. The total solar-to-electric energy conversion efficiency of the NWs+a single layer of NPs was found to be 2.28%, with a short-circuit photocurrent density (JSC) of 3.02 mA/cm2, open-circuit voltage (VOC) of 0.74 V, and a fill factor (FF) of 0.76, which is 60% higher than that of NWs cells and over 165% higher than NWs+a triple layer of NPs-based DSSCs....
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.