Infiltration of Spiro-MeOTAD hole transporting material into nanotubular TiO2 electrode for solid-state dye-sensitized solar cells (original) (raw)
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Dye-sensitized solar cells based on TiO2 nanotube/porous layer mixed morphology
Applied Physics A, 2008
Titania porous layer has been fabricated on titania nanotubes for dye sensitized solar cells and the photovoltaic performance of solar cells with mixed morphology has been investigated. The porous layer results in a similar improvement in the short circuit current density to conventional TiCl 4 treatment, although the mechanisms responsible for the observed increase in the efficiency are different. This enables further improvements of the photovoltaic performance by combining the TiCl 4 treatment and porous layer deposition, so that the efficiency in the case of ∼5 µm long tubes increases on average from ∼1.6 to ∼2.2%.
Synthetic Metals, 2001
Solid state dye-sensitized photovoltaic solar cells were fabricated using a three-layer concept. The hybrid devices consist of a transparent inorganic nanocrystalline titanium dioxide (nc-TiO 2 ) layer with a thickness of 2 mm as electron acceptor and for electron transport. A surface-adsorbed RuL2(NCS)2:2 TBA dye complex (where L 2,2 H -bipyridyl-4,4 H -dicarboxylic acid; TBA tetrabutylammonium) is utilized for light absorption and electron injection to the conduction band of TiO 2 . For the transport of holes to the back contact electrode conjugated polymers are used, either a poly(3-octylthiophene) (P3OT), or a low band-gap thiophene±isothianaphthene-based copolymer (PDTI). These devices exhibit an overall energy conversion ef®ciency of approximately 0.16% under simulated solar irradiation (80 mW/ cm 2 ). Furthermore, we have investigated the surface network morphology of these ®lm layers by atomic microscope (AFM) exploring strategies to improve the ef®ciency. #
Small diameter TiO2 nanotubes vs. nanopores in dye sensitized solar cells
Electrochemistry Communications, 2012
Highly ordered nanoporous and nanotubular TiO 2 geometries can be anodically grown on Ti substrates in fluoride containing ethylene glycol electrolytes using different water contents. Here we fabricate 1 μm thick layers consisting of arrayed tubes or pores with an open diameter of 15 nm. We compare these small diameter structures to classical 100 nm diameter TiO 2 nanotubes for their application in Grätzel-type solar cells. The results show clearly that a small diameter nanotube geometry significantly enhances the solar cell conversion efficiency.
TiO2 nanotubes infiltrated with nanoparticles for dye sensitized solar cells
Nanotechnology, 2011
We present a detailed study of the infiltration of titanium dioxide (TiO2) nanotubes (NTs) with TiO2 nanoparticles (NPs) for dye sensitized solar cells (DSSCs). The aim is to combine the merits of the NP's high dye loading and high light harvesting capability with the NT's straight carrier transport path and high electron collection efficiency to improve the DSSC performance. On infiltrating NTs with TiCl4 solution followed by hydrothermal synthesis, 10 nm size NPs were observed to form a conformal and dense layer on the NT walls. Compared with the bare NT structure, dye loading of this mixed NT and NP structure is more than doubled. The overall photon conversion efficiencies of the fabricated DSSCs are improved by 152%, 107%, and 49% for 8, 13, and 20 µm long NTs, respectively. Electron transport and recombination parameters were extracted based on electrochemical impedance spectroscopy measurements. Although a slight reduction of electron lifetime was observed in the mixed structures due to enhanced recombination with a larger surface area, the diffusion length is still significantly longer than the NT length used, suggesting that most electrons are collected. In addition to dye loading and hence photocurrent increment, the photovoltage and filling factor were also improved in the mixed structure due to a low serial resistance, leading to the enhancement of the overall efficiency.
Study of Titanium Dioxide Nanotube Array for the Application in Dye-Sensitized Solar Cells
International Journal of Materials, Mechanics and Manufacturing, 2014
Highly ordered, self-organized TiO 2 nanotube arrays (TNA) have been successfully prepared by anodization of titanium foil in ethylene glycol electrolyte containing 0.01% ammonium fluoride (NH4F). The effect of variation of applied anodization voltage ranging from 50V to 57 V on the morphology of the TNA has been studied using field emission scanning electron microscope. The increase in applied voltage enhances average pore size from 34nm to 58nm and reduces wall thickness. Diffuse reflectance spectroscopy has been used to evaluate the amount of dye absorption on the surface of various TNA which reveals direct correlation between the dye absorption and the morphology of the sample.
Synthetic Metals, 2006
A study of a hybrid heterojunction solar cell based on nanocrystalline mesoporous TiO 2 and the hole conductor spiro-OMeTAD (2,2 7,7tetrakis(N,N -di-p-methoxyphenyl-amine)-9,9 -spiro-bifluorene) has been realized. Impedance and cyclic voltammetry techniques were used to measure the interfacial properties of the hybrid heterojunction and establish the energy levels of the solid-state electrolyte. It was observed that the energy levels of the organic hole transport material are changed when it forms a film deposited onto indium-doped tin oxide (ITO). Moreover, the HOMO level of the mono oxidized spiro-OMeTAD is well coupled with the HOMO level of the dye N719 (Ru(4,4 -dicarboxy-2,2 -bipyridyI) 2 (SCN) 2 ) which implies that it is not convenient to increase the doping of the hole conductor much further than this first oxidized state. This doping level (n ≈ 10 19 cm −3 ) also assures a high enough hole conductivity. The implications of our results to the solid-state dye solar cell performance are discussed.
Current Applied Physics, 2011
The porous nanotubes were successfully fabricated by coating a porous layer on the walls of the TiO 2 nanotubes. This method was proved available for effectively increasing the specific surface area of the nanotubes. The DSSCs based on such porous nanotubes has a higher conversion efficiency than that of the DSSCs using common TiO 2 nanotubes. This could be explained by the enhanced loading of dye molecules on porous TiO 2 nanotubes, which resulted in the improvement of short-circuit current. The light to electric energy conversion efficiency of the DSSCs applying porous TiO 2 nanotubes is about 1.79% nearly two times higher than that of the DSSCs based on normal TiO 2 nanotubes.