Study on enhancement of photoelectrochemical performance and stability using high-efficiency Cu(In,Ga)$Se_2$ photocathode for hydrogen evolution and demonstration of unassisted solar-to-hydrogen conversion cell

Abstract

Since the first report of photoelectrochemical (PEC) water splitting using a $TiO_2$ photocatalyst by Fujishima and Honda in 1972, there have been steady reports of PEC properties of various semiconductors. Efficient PEC water splitting is important for next generation energy storage to mitigate dependence on fossil fuels, which facilitates energy conversion from sun light to storable form of chemical fuel such as hydrogen. In this thesis, PEC properties of the p-type Cu(In,Ga)$Se_2$ photocathode for hydrogen evolution, which is one of the copper chalcogenide compounds, and also a strategy to improve the PEC performance and stability of the Cu(In,Ga)$Se_2$ are investigated. Finally, a method to achieve high solar-to-hydrogen conversion efficiency of 8.1% via PEC-PV cell for unassisted water photolysis will be discussed.