• Jiao, Jun
• Jeffryes, Clayton
• Rorrer, Gregory L.
• Gutu, Timothy
• Li, Haiyan

Abstract

<jats:title>Abstract</jats:title><jats:p>Biological fabrication approaches were used to enhance the performance of a dye-sensitized solar cell (DSSC) device stack for the conversion of light to electricity. Diatoms are single-celled algae that make silica shells called frustules that possess periodic structures ordered at the micro- and nanoscale. Nanostructured TiO<jats:sub>2</jats:sub> was deposited onto the frustule biosilica of the diatom <jats:italic>Pinnularia sp</jats:italic>. Poly-L-lysine (PLL) conformally adsorbed onto surface of the frustule biosilica. The hydrolysis and condensation of soluble Ti-BALDH to TiO<jats:sub>2</jats:sub> by PLL-adsorbed diatom biosilica deposited 0.77 ± 0.05 g TiO<jats:sub>2</jats:sub>/g SiO<jats:sub>2</jats:sub> onto the diatom biosilica. The periodic pore array of the diatom frustule served as a template for the deposition of ˜20 nm TiO<jats:sub>2</jats:sub> nanoparticles, which completely filled the 200 nm frustule pores and also coated the frustule outer surface. This material was then integrated into the DSSC device stack. Specifically, a single layer of diatom-TiO<jats:sub>2</jats:sub> frustules was deposited to surface coverage 100μg/cm<jats:sup>2</jats:sup> on top of the 25 nm anatase TiO<jats:sub>2</jats:sub> nanocrystal layer (2.5 mg/cm<jats:sup>2</jats:sup>) that was doctor-bladed onto conductive FTO glass. The composite structure was thermally annealed in air at 400 °C, followed by addition of N719 dye, I<jats:sub>3</jats:sub>-/3I- liquid electrolyte, and semi-transparent Pt back electrode sputter coated on FTO glass. The solar cell efficiency increased from 0.20% to 0.70% when the diatom-TiO<jats:sub>2</jats:sub> layer was added to anatase TiO<jats:sub>2</jats:sub> base layer of the semi-transparent device. The increase in efficiency cannot be attributed solely to the added TiO<jats:sub>2</jats:sub>, because the amount of TiO<jats:sub>2</jats:sub> in the diatom-TiO<jats:sub>2</jats:sub> layer contributed to only 3% of the total TiO<jats:sub>2</jats:sub> in the device. Instead, it is proposed that the diatom-TiO<jats:sub>2</jats:sub> layer may have helped to improve photon capture within the DSSC because of its periodic structure and high dielectric contrast.</jats:p>

Topics

• nanoparticle
• Deposition
• impedance spectroscopy
• pore
• surface
• glass
• glass
• composite