Nanoparticulate Hollow TiO₂ Fibers as Light Scatterers in Dye‐Sensitized Solar Cells: Layer‐by‐Layer Self‐Assembly Parameters and Mechanism

Abstract

Hollow structures show both light scattering and light trapping, which makes them promising for dye-sensitized solar cell (DSSC) applications. In this work, nanoparticulate hollow TiO(2) fibers are prepared by layer-by-layer (LbL) self-assembly deposition of TiO(2) nanoparticles on natural cellulose fibers as template, followed by thermal removal of the template. The effect of LbL parameters such as the type and molecular weight of polyelectrolyte, number of dip cycles, and the TiO(2) dispersion (amorphous or crystalline sol) are investigated. LbL deposition with weak polyelectrolytes (polyethylenimine, PEI) gives greater nanoparticle deposition yield compared to strong polyelectrolytes (poly(diallyldimethylammonium chloride), PDDA). Decreasing the molecular weight of the polyelectrolyte results in more deposition of nanoparticles in each dip cycle with narrower pore size distribution. Fibers prepared by the deposition of crystalline TiO(2) nanoparticles show higher surface area and higher pore volume than amorphous nanoparticles. Scattering coefficients and backscattering properties of fibers are investigated and compared with those of commercial P25 nanoparticles. Composite P25-fiber films are electrophoretically deposited and employed as the photoanode in DSSC. Photoelectrochemical measurements showed an increase of around 50% in conversion efficiency. By employing the intensity-modulated photovoltage and photocurrent spectroscopy methods, it is shown that the performance improvement due to addition of fibers is mostly due to the increase in light-harvesting efficiency. The high surface area due to the nanoparticulate structure and strong light harvesting due to the hollow structure make these fibers promising scatterers in DSSCs.

Facile hydrothermal preparation of titanium dioxide decorated reduced graphene oxide nanocomposite

“…6,[12][13][14][15][16][17][18] Nanocrystalline titanium dioxide (TiO 2 ) is a promising candidate for solar energy conversion applications such as photocatalysis, photochromism, and photovoltaics because of its unique optical and electrical properties. 19 It is widely used in applications such as hydrogen production, 20,21 gas sensors, 22,23 photocatalytic activities, 24,25 and dye-sensitized solar cells 26,27 because of its relative high efficiency and high stability.…”

Template-based syntheses for shape controlled nanostructures

“…Cellulose nanofibers have been used for production of inorganic nanotube structures, including hollow TiO 2 fibers [134,135], SnO 2 nanotubes [136,137], Fe 2 O 3 nanotubes [138], and SiO x nanotubes [139]. The main advantage of cellulosic fibers is that long fibers (in the range of 10 μm) can be produced with this method.…”

“…The LbL techniques provide the ability to deposit nanoparticles on the surface of the cellulosic fibers and hence, the nanostructured hollow fibers will be produced. The nanostructured fibers are important for application which high surface area and electrolyte diffusion are important such as batteries and solar cells [134]. Ghadiri et al [140] used sol-gel process for deposition of TiO 2 on the surface of the cellulosic fibers.…”

“…However, in the many instances for templating nanotubes, commercial cellulosic membranes and loose fibers are used, which are random in structure and vary from micrometer [141] to nanometer [142] to aerogel varietals [143]. Treatments done in order to improve the dispersion of cellulosic fibers, but obtaining the nanofibers as suggested is quite unpredictable and difficult to achieve in the sense of a supported template membrane [144].…”

Interaction of Titanium (IV) Chloride Vapor with Cotton Cellulose and Catalytic Properties of the Titanium Dioxide Obtained

“…Среди недостатков методов получения таких волокон нанесением на целлюлозу отмечены сложность процедур и проблема разрушения трубок в процессах их приготовления. Весьма трудоемкие процессы получения полых волокон диоксида титана, включающие последовательное нанесение до девяти слоев золь-гель-методом, описаны в [6].…”