ABSTRACT
The current energy challenge is to a large extent a challenge to find affordable, stable, and preferably mostly re-useable materials. The materials challenge includes finding the most suitable materials to facilitate converting between different forms of energy: solar, heat, electrical, chemical, storage energy, and kinetic energy. Here, we focus on the currently large materials research motivated by the conversion of solar energy into electricity via exploring nanostructured silicon. As the goal addresses the global energy challenge the research results have clear applications beneficial to mankind. Today, silicon dominates the active material for energy conversion of solar energy, which is related to the matured infrastructure for making photovoltaic solar cells. Finding better and less-expensive materials that are more energy efficient to produce and have better conversion efficiencies would benefit the global transition to renewable energy, but it is a large challenge, especially with respect to sustainable mass production. Various micro- or nano-structures based on silicon have been proposed as promising materials with great potential for solar energy harvesting, conversion, and current progress on this effort will be presented and discussed here. The use of silicon nanostructures has the potential to use less silicon for a device, which would reduce the direct cost and the embodied energy cost. In order to maintain high efficiency surface nano-structures are being developed to trap incident photons in thin silicon films (to overcome the weak absorption of silicon). This is designed to result in a reduced reflectivity of visible light compared to a silicon wafer surface. Surface nanostructures would eliminate the need for a separate silicon nitride anti-reflection coating, which is commonly used today. For improved performance in industry-scale applications, Si materials with delicate nanostructures and ideal compositions in massive production are highly cherished. The recent progress on the as-reduced Si products for energy conversion is presented systematically. Moreover, some cutting-edge fields involving Si materials are discussed, which may offer deep insights into the rational design of advanced Si nanostructures for extended energy-related applications.
