Synthesis of Chalcopyrite and Dicationic Materials for Energy Applications

Abstract

Nowadays, we are facing an exhaustion of petroleum resources. It gives cause for an energy crisis. The energy crisis is not a short-term problem. To solve the problem renewable energy is in the limelight. Renewable energy is energy which comes from natural resource such as wind, tides, geothermal heat and sunlight. Above all, sunlight has the greatest potential of any renewable energy resource to solve the problem. Because of this reason, we investigate solar energy conversion applications. One of them is a photovoltaic device which normally uses silicon panels to convert sunlight into electricity. However, the major problem with conventional silicon solar energy system is its high cost of production. Therefore, we need to make down the cost of production. To cut the cost of solar cell materials, many researchers study various materials. CuIn1-xGaxSe2 (CIGS) is one of the promising materials for photovoltaic devices. It is a direct-band gap material thus has a large optical absorption coefficient. Several groups have demonstrated high-efficiency CIGS solar cells using physical vapor deposition (PVD) and sputtering technique. However, these methods are not only expensive and limited scale up. Electrodeposition is suitable methods to get low-cost precursor films. In this thesis, the electrodeposition was carried out potentiostatically in an electrochemical cell in a non-stirred solution. Electrodeposition prepared by using a three-electrode cell in which the reference electrode was saturated calomel electrode, the counter electrode was a Pt sheet, and the substrate was Mo/glass. Also, dye-sensitized solar cells (DSSCs) have been receiving growing attentions as a potential alternative to order photovoltaic devices due to their high efficiency and low manufacturing cost. DSSCs are composed of a photosensitizing dye adsorbed on a mesoporous film of nanocrystalline TiO2 as a photoelectrode, an electrolyte containing triiodide/iodide redox couple, and a platinized counter electrode. To improve photovoltaic properties of DSSCs, new dicationic salts based on ionic liquids were synthesized. Quite comparable efficiencies were obtained from electrolytes with new dicationic iodide salts.