PLASMONIC METAL-SEMICONDUCTOR HETEROJUNCTIONS FOR SOLAR ENERGY CONVERSION

摘要

Solar energy can be converted by three means: solar thermal power generation devices, photovoltaics and photocatalysts (or photoelectrochemical cells (PECs)). Both photovoltaics and photocatalysts are built on the semiconductor. The conversion of solar radiation by semicondcutors is fundamentally limited by the heating losses in charge carriers with excess energy above the band gap of the semiconductor. The balance of increased light absorption with increased thermalization losses makes a band gap of ~1.3 eV most efficient for photovoltaics according to the Schockley-Queisser limit, and ~1.9 eV for water splitting according to the energy necessary to drive water photolysis.. Hence single semiconductor-based photovoltaics and photocatalysts cannot harvest a large portion of solar radiation in the visible-light and near-infrared light regions. Formation of heterojunctions is an effective route to mitigate this problem. Plasmonic metal nanostructures can be incorporated with the semiconductor to form a heterojunction, in which the plasmonic metal can serve as the photosensitizer.