From Sunlight to Electricity: Exploring Nanocrystals for Solar Energy Conversion

Currently, nanomaterials are defined in the range of 0.1-100 nanometers. When the particle size is less than 100 nanometers, the number of atoms on the surface of the particles is comparable to that in the body. For example, 5 nanoparticles have a surface atomic ratio of 40% and a specific surface area of 180 square meters per gram. This leads to the appearance of small size nanomaterials which are different from the traditional solid materials or their bulk counterparts, due to the change of the structure and energy state caused by the surface effects [35] and quantum tunnel effects [36]. Many unique physical and chemical energies, such as light, electricity, magnetism and mechanics, have been produced by the changes. For example, nano-iron has magnetic properties, the original non-conductive materials become conductive, special far-infrared radiation, strong ultraviolet reflection, strong catalysis, strong adsorption and so on [37-38].