Graded Multilayered TiO₂ Photoelectrode for Improving the Performance of Dye Solar Cells

Abstract:

Numerous research have been conducted to improve the efficiency of dye solar cell (DSC) through the study on its components namely the dye, electrolyte, counter electrode and the photoelectrode material. This paper presents the study on the usage of a multilayered structure with different composition of TiO₂ nanoparticles/aggregates composites starting with the top layer consisting of purely aggregates and ending with the bottom layer consisting of wholly nanoparticles as the photoelectrode material. The graded composition profile of increasing amount of aggregates at the top of the photoelectrode and increasing amount of nanoparticles at the bottom of the photoelectrode will allow for the enhancement in the optical properties and kinetics of DSC. The layers were screen-printed onto FTO coated glass substrate to form the photoelectrodewith an active area of 1 cm2 and thickness of 12 µm. The N719 dye-coated TiO2 electrode was then assembled into sandwich configuration with platinized conducting glass electrode and injected with iodide/tri-iodide redox couples electrolyte.Kinetics and the underlying transport properties of the assembled DSCs were measured by Electrochemical Impedance Spectroscopy (EIS). The response of the cells towards a spectrum of light frequencies was measured using Incident Photon to Electron Conversion Efficiency (IPCE). Conversion efficiency was measured using a 100 mW/cm2 solar simulator. Highest efficiency was found for the multilayered photoelectrode configuration at 4.58% with 14% improvement over the DSC with pure aggregate.DSCs with the multilayered composite configuration have higher current density, Jscwith an increase of 2.249 mA cm-1 compared to the one with only nanoparticles and only aggregates layer. Multilayer configuration has shown significant improvement in the quantum efficiency by exhibiting higher light absorption especially in the range of 500-550 nm light wavelength by about 12.9%.The increase in the conversion efficiency of DSCs with multilayer configuration is also attributed to the improvement in the electron diffusion as evident by the EIS measurement.

• Periodical: Materials Science Forum (Volume 756)
• Pages: 190-196
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.756.190
• Online since: May 2013
• Authors: Adel Eskandar Samsudin, Muti Mohamed Norani
• Keywords: Electrochemical Electrodes, Electrochemical Impedance Spectroscopy (EIS), Electrolytes, Measurement Systems, Solar Cell, Sunlight

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