Please use this identifier to cite or link to this item: http://scholarbank.nus.edu.sg/handle/10635/32474
Title: Nanostructured metal-oxide materials for dye-sensitized solar cells
Authors: AGARWALA SHWETA
Keywords: Solar Cell, Titanium Dioxide, Iron oxide, Nanoparticle, Mesoporous, Nanotube
Issue Date: 12-Jul-2011
Source: AGARWALA SHWETA (2011-07-12). Nanostructured metal-oxide materials for dye-sensitized solar cells. ScholarBank@NUS Repository.
Abstract: Global warming and depletion of fossil fuels have sparked extensive research for clean energy sources such as solar cells around the world. Dye-sensitized solar cells (DSSC) are currently subject of intense research as a low-cost photovoltaic device. Among the versatile group of semiconductors nanostructures used for this device, metal-oxides stand out as one of the most common and most diverse classes of materials with extensive structural, physical and chemical properties and functions. The structure, properties and function of small oxide domains, however, depend sensitively on their sizes and shapes. The nanostructured metal oxides offer many new opportunities to study fundamental surface processes in a controlled manner and thus lead to fabrication of new devices. The main objective of this work is to synthesize nanostructures of titanium dioxide and iron oxide and understand their growth mechanisms; so that theoretical and practical foundations for future large-scale production of these nanostructures can be laid. In this work the possibility of using the synthesized morphologies as new electrode material for DSSC is explored. Functionality of various nanostructures is investigated through chracterization of microstrcture, electronic properties and optical properties. The metal-oxide nanostructures are promising materials to improve the efficiency of DSSC due to enhancement of surface area, light trapping and efficient electron transport. Solution based synthesis mechanism is adopted to grow these nanostructures. We understand the role of morphologies on electron transport and thus deduce the main reason for electron and efficiency loss. Another part of the thesis deals with addition of different additives and counter ions in iodide based quasi-solid electrolyte system. The work involves optimizing the quasi-solid electrolyte in order to be effective in DSSC. We explain and understand the practical advantages of the new electrolyte systems in comparison to the classic quasi-solid state electrolytes. The thesis is organized into eight chapters. Chapter 1 presents an extensive literature review, necessary to understand the materials and device functioning. Chapter 2 introduces the materials and methods applied in the present study. This includes synthesis of materials, fabrication of solar cell device and characterization techniques to investigate the working of the nanostructures and device performance. Chapter 3 describes the use of high surface area mesoporous TiO2 film in DSSC. This chapter also discusses the influence of incorporating scattering centers in the TiO2 film and its effects on the solar conversion efficiency of DSSC. Chapter 4 discusses the process of anodization of titanium foil to synthesize TiO2 nanotubes. Effect of TiO2 nanotube parameters and influence of silver (Ag) nanoparticles is studied on the efficiency of DSSC. Chapter 5 demonstrates a material shift for the photo-electrode by discussing Fe2O3 nanoflowers and their effects on DSSC. This chapter discusses the possible growth mechanism of such unique nanostructures and finds a relation between the structure and its function in DSSC. The main aim of chapter 6 is to develop a stable and filler-free quasi-solid state electrolyte system. Results and discussion section of this chapter throws light on the intricate working of this novel LiI and KI based iodide electrolyte. Chapter 7 concludes the thesis and finally, chapter 8 gives some directions for future work.
URI: http://scholarbank.nus.edu.sg/handle/10635/32474
Appears in Collections:Ph.D Theses (Open)

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