A CdS/CdSeTe with Carbon Nanospheres Sensitized Solar Cell with a Reduced Graphene Oxide Counter Electrode: Fabrication and Characterization

Laha, Subhajit and M, Deepa (2015) A CdS/CdSeTe with Carbon Nanospheres Sensitized Solar Cell with a Reduced Graphene Oxide Counter Electrode: Fabrication and Characterization. Masters thesis, Indian Institute of Technology Hyderabad.

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Abstract

To make Quantum Dot Sensitized Solar Cells (QDSSCs) competitive, it is necessary to achieve power conversion efficiencies comparable to other solar cell technologies. In this work, a photoactive electrode consisting of CdS (visible light absorbing) and CdSeTe (alloyed quantum dots with an excitonic absorption onset at 859 nm) and Carbon Nanospheres (CNS) were prepared by assembling them onto a mesoporous TiO2 electrode for the first time. Carbon Nanospheres were prepared from starch by an acid treatment and they were dissolved in ethanol and deposited onto TiO2 electrophoretically. CdS QDs were formed over TiO2 and the TiO2/CNS electrodes by SILAR (Successive Ionic Layer Absorption and Reaction) method and CdSeTe QDs were deposited over them by an electrophoretic deposition method. Both the electrodes (photoanode and cathode) were characterized by electron microscopy, cyclic voltammetry, Raman and X-ray diffraction analyses. QDSSCs were constructed with photoanodes of different compositions, and with a 0.1 M Na2S in water-methanol (3:7) solution as electrolyte and a Reduced Graphene oxide based counter electrode. The best overall power conversion efficiency was achieved for the TiO2/CNS/CdS/CdSeTe photoanode-based cell and it is 2.82%. The use of a near-infrared absorber like CdSeTe and electron acceptors like Carbon nanospheres in realizing remarkable improvements in solar-cell performance metrics is demonstrated.

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