Synthesis and First-principle Calculation of TiO2 Rutile Nanowire Electrodes for Dye-sensitized Solar Cells

• In this paper, a TiO2 nanowire film synthesized via a hydrothermal method was prepared as a photoanode for dye-sensitized solar cells (DSSCs). The synthesized TiO2 nanowires were characterized by transmission electron microscopy and X-ray diffraction. The TiO2 nanowire film greatly improved the efficiency of the DSSC owing to the rapid interfacial electron transport in the one-dimensional TiO2 nanowires. The light absorption and interfacial electron transport, which play important roles in the efficiency of DSSCs, were investigated by UV-vis absorption spectroscopy and electrochemical impedance spectroscopy. The energy band structure and electron density of states of the rutile nanowire were calculated using a first-principles method and compared to bulk anatase and rutile TiO2 phases. The band gap of the rutile TiO2 nanowire was found to be less than that of anatase TiO2 by 0.6 eV. Further calculations using GGA+U yielded a similar band gap reduction. In addition to the redshift of the absorption edge originating from the smaller band gap, the larger surface area of the TiO2 nanowire compared to the bulk material is expected to facilitate the migration of photogenerated electrons and holes from inside to the surface of the material. This would result in a considerable improvement of the photocatalytic efficiency of TiO2.

Ämnesord

NATURVETENSKAP  -- Kemi -- Materialkemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Materials Chemistry (hsv//eng)

Nyckelord

TiO2

Nanowire

First-principles

Band gap

DSSCs

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