Evaluation of modified nano-siO2/tiO2 as a photoanode material for dye-sensitized solar cell

• Main Author: Lau, Stephanie Chai Tying
• Format: Thesis
• Language: English
• Published: 2016
• Subjects: TP Chemical technology
• Online Access: https://eprints.ums.edu.my/id/eprint/17526/1/Evaluation%20of%20modified%20nano-siO2tiO2.pdf; https://eprints.ums.edu.my/id/eprint/17526/
• Institution: Universiti Malaysia Sabah

Dye-sensitized solar cells (DSSC) have been extensively studied due to their. promising potential for high efficiency, low production cost and eco-friendly production. The photoanode of DSSC is usually composed of randomly packed TiO₂ nanoparticles. However, high surface charge recombination rate of the TiO₂ nanoparticles accounts for its low efficiency. In this research, nanosilica between 20 to 100 nm was synthesized via Stober method and surface modified with aminopropyltriethoxysilane (APTES) and glycidoxypropyltriethoxysilane (GPTS) to produce nanosilica with reduced band gap and increased isoelectric point for photoanode material application. The photoanode was fabricated with the pure nanosilica, modified nanosilica, pure nanosilica/TiO₂ composite and modified nanosilica/TiO₂ composite respectively. Finally, DSSCs was constructed with the photoanode electrode made, N719 dye, iodide redox couple liquid electrolyte and Platinum counter electrode. The synthesized pure nanosilica of 22.9 + 2.5 nm has a band gap of 5.1 eV. The result showed that nanosilica modified with APTES has a lower band gap (Le. 2.7 eV) and higher isoelectric point (Le. pH 8.9) than the pure nanosilica. Nanosilica modified with GPTS however was unsuccessful synthesized. The photoanode with APTES modified nanosilica was sintered at 200 ⁰C (normal sintering temperature is 450 ⁰C) due to its thermal instability at temperature higher than 200 C. DSSC with composite of 10 wt.% of pure nanosilica/ TiO₂ sintered at 450 ⁰C showed the highest efficiency of 4.61 % which was higher than the pure TiOz₂ based DSSC sintered at 450 DC (2.61 %). Mixing of nanosilica increased the total specific surface area of composites for dye adsorption and increases the DSSC efficiency. This study shows that DSSC with composite of 10 wt.% of APTES modified nanosilica/TiO₂ sintered at lower sintering temperature of 200 DC has higher efficiency of 3.33 % compared to DSSC with composite of 10 wt% of pure nanosilica/TiO₂ sintered at 200 ⁰C (1.61 %). This results showed that APTES modified nanosilica was successful in improving DSSC efficiency in a composite material.