Periodic semiconductor nano-structures for the enhanced photovoltaic devices

Abstract

The photovoltaic devices which convert the solar energy to the electrons or chemical materials become very important clean energy devices due to the environmental pollution from the fossil energy. The Dye-sensitized Solar cell (DSSC) which generates the electron-hole pairs using solar light and photoelectrochemical cell (PEC), one of the promising clean energy solar cells for capturing and storing solar energy by splitting water into a hydrogen and oxygen gas have received extensive attention because of high performance and low price. Enhancing optical property is the one of the fascinate strategy for the increasing the properties of photovoltaic devices. Interference lithography (IL) is a very convenient and fast method to fabricate the two/threedimensional polymer template in a submicrometer scale. By combining an IL technique and hydrothermal growth, the high crystalline periodic semiconductor nanowires such as ZnO, TiO2 and Fe2O3 can be fabricated. The 2D patterned semiconductor nanowires can be considered as a diffraction grating layer which can enhance the optical property for increasing the overall performance of photovoltaic devices such as DSSC and PEC. In this thesis, I studied on the synergetic effects of the IL technique and the hydrothermal growth method for enhancing the optical properties. The patterned nanowires with a subwavelength scale that act as the diffraction grating layer can increase the optical path in the photovoltaic devices. Especially, the absorption of visible wavelength of solar light (400nm ~ 800nm), a major source to generate the electron-hole pairs in the photovoltaic cells can be enhanced by the pattern nanowires. The outstanding properties of the 2D patterned nanowires suggest the great potential in energy-related devices such as DSSCs, PEC cells and sensor devices such as SERS.